In retrospect, I realize that I could have stated my hypothesis about historic range more explicitly in the Bits ‘n’ Pieces series, here, here, here, here, here, and here. My treatment of this subject draws on and expands upon Tanner, Jerome Jackson’s extensive review of the historical record, the work of Benjamin Leese, and Appendix E in the U.S. Fish and Wildlife Service’s Ivory-billed Woodpecker Recovery Plan, supplemented by my own research and review of the source material.
I got somewhat too focused on specimen records and even more so on habitat types. The version of the map I created for the series reflects that focus, by including barrier islands, for example. The subjects of range and habitat are of course intertwined, but I’ll state the hypothesis with respect to range upfront and follow it with a more detailed discussion:
The Ivory-billed Woodpecker’s range was considerably more extensive and than is recognized by the general public and than has been represented in much of the literature, both popular and scientific. All published range maps of which I’m aware, including Hasbrouck’s (1891), Tanner’s (1942), Jackson’s revised and redrawn version of Tanner (2004), and online, poorly reflect the historic range, especially east of the Mississippi.
This has implications in terms of habitat requirements and adaptability as well.
I suggest that the northern limit of the ivorybill’s range was just above 40 degrees North and that the western limit was approximately 98 degrees West. There are no archaeological or other records from over 2000′, so I’d exclude higher elevations in the Appalachians and Ozarks. I think the previous maps are accurate to the extent that they show the range as extending farther west in the Red and Arkansas River basins than in the Missouri.
To express it somewhat differently, I think ivorybills could be found as far north as the lower Delaware River on the Eastern Seaboard and that they could be found in riparian corridors into the lower reaches of the Appalachians from there south.
In Florida, I think it’s conceivable that the range extended to the Upper Keys. In the southwest, I’d draw the line near Port Lavaca, Texas to west of Tulsa, Oklahoma. Except for an archaeological find in northeastern Nebraska that almost certainly involved trade items, the northernmost specimen record from west of the Mississippi is from Forest Park, MO (more on that below).
The story seems to have been somewhat different in the Ohio River watershed, where both archaeological evidence and sight records suggest that birds were present far upstream from the Mississippi confluence and along tributaries well north of the river itself.
I’ve created another map showing both the limits of my hypothesized range and selected reports from what could be considered the edges of that range. A screen cap is below. Click on this link for annotations. Although some of the records are pre-Columbian (the earliest estimated as dating to 0-200 CE/AD), I suspect this was the approximate range until the mid to late-18th century.
Thus my hypothesized range is considerably more extensive than the conventional one (shown immediately below). On the Eastern Seaboard, it extends much farther north and also farther inland. It is far greater within the Mississippi watershed, extending to north of Columbus, Ohio, and encompassing all but the higher elevations in the Appalachians (based on the archaeological site at 2000′ near Lebanon, VA), reaching farther north and west in Arkansas and Missouri.
It was also somewhat more extensive in Texas and Oklahoma, reaching farther into the plains and a little farther south than the maps suggest. Outside of coastal areas, the presence was probably limited to riparian corridors, with those in the western part of the range (at least) being narrow. The version below is from the IUCN Red List entry for the ivorybill.
While what I’m suggesting may seem heretical to some, it’s well-supported by the archaeological record, accounts from early explorers and naturalists, and collection records or reports thereof, albeit to a lesser extent. I covered many of the records that led to my formulating this hypothesis in previous posts; I won’t recapitulate all of them here, but one passage is worth revisiting. Two notes on technical terminology: middens are most easily defined as “dumps for old domestic waste“, and tarsometatarsi are the lower leg bones found in birds (and some dinosuar fossils).
If our knowledge of the Ivory-billed Woodpecker were based on the archaeological record alone, we’d think of it as an upland species. Further, we might very well assume that it ranged from the hills of Georgia, to the Alleghenies in Virginia, to central Ohio and west-central Illinois.
The remains found in Native American middens were unlikely to have been trade goods; ivorybill parts seem to have been a valuable commodity for ceremonial use west of the Mississippi but not east of it, and in several cases, the remains found were tarsometatarsi, which would be consistent with use as food:
There is strong physical evidence of ritual value for woodpecker scalps and bills from the upper Midwest and Plains . . . Remains of the Ivory-billed Woodpecker can be found in sacred bundles, on pipe stems, on amulets, and with burials among the Native Americans of the region. The evidence comes from the western Great Lakes and the Plains; no evidence of a particular use of Ivory-billed Woodpeckers has yet been uncovered from the eastern area of the Great Lakes (Ohio, Indiana, and Michigan).
(Leese, 2006.) Leese also points out (in several of his publications) that there’s no evidence that ivorybill parts other than scalps and bills had any trade value.
In an unpublished 1989 update to his monograph (housed in the archives at Cornell), Tanner accepted additional reports, including archaeological finds from Scioto County, Ohio (15th or 16th-century) and Madison County, Illinois (Cahokia Mounds, approximately 15th-century), as well as a collection record from Forest Park, Missouri and an 18th century record from Lincoln County, Kentucky. Since that time, additional archaeological records from Georgia, Virginia, West Virginia, and Ohio have turned up.
Thus, the case for ivorybill presence both in the lower reaches of the Appalachians and well up the Ohio River (and its tributaries) is compelling, and any suggestion that items found in Native American middens might be trade goods is pure speculation with no evidence to support it.
In a paper titled, “Putative Records of the Ivory Billed Woodpecker in Pennsylvania and the Mid-Atlantic” (2016 Pennsylvania Birds, 20(2):71-72), Leese suggested that eastern Pennsylvania and Southern New Jersey might be the northern limit on the Atlantic Coast. I agree and might even go a step further and argue that the available evidence strongly supports that view. The discussion below relies heavily on material Leese discovered, though I disagree with Leese’s conclusion that a more extensive range and more varied habitats support Snyder’s argument that hunting was the “main cause of the species’ extinction”.
This idea that ivorybills ranged so far north on the East Coast will probably be the hardest for many to swallow. Bear in mind, however, that Audubon described the ivorybill as an accidental in Maryland. Audubon’s discussion of range is odd; he didn’t mention Florida, and there’s nothing to support the idea that the western part of the range extended to the foothills of the Rockies. But he would have been far better informed about the Eastern Seaboard.
In any event, his description dates to the 1820s, by which time the range was likely shrinking. As discussed previously in the series, I suspect that the extirpation of the beaver played a major role in the ivorybill’s decline outside of Florida. Beavers were probably extirpated in New Jersey by 1820 (Van Gelder 1984). It’s reasonable to infer a similar date for eastern Pennsylvania.
To expand on this beyond the previous posts in the series, Peter Kalm, a prominent European naturalist and student of Linnaeus, listed the ivorybill as present in the Delaware Valley and distinguished it from the Pileated, which he described as “a Black Woodpecker with a red head” and “frequent in the Pennsylvanian forests”.
It’s not clear whether Tanner was aware of Kalm’s 1749 record, which was described in The Auk in 1903. The author of that paper suggested that this record should be taken “cum grano salis,” primarily because there have been no other records from the state. Or have there?
While it is ambiguous, Leese discovered a letter from Alexander Wilson, written during the early years of his career, when he was living on William Bartram’s property near Philadelphia; it is strongly suggestive of ivorybill, describing a large and “most extraordinary Blackheaded Woodpecker”. This was at a time when Wilson seemed to be in the process of learning his birds, and he did not mention it in later correspondence, which leaves room for doubt.
While Wilson’s description is not very detailed, I find it suggestive. And as noted previously, I think the only basis for rejecting Kalm’s account (and he seems to have otherwise been meticulous) is what we think we know about the ivorybill, a knowledge base derived from observations dating to between 60 and 190 years later. While there’s no way to prove it, I think Kalm’s listing should be treated as credible; it would be if a more common species were involved. Leese mentioned a couple of additional 18th century reports from Pennsylvania (included on the map) but found them questionable.
I’m not aware of anyone else having made this observation, but I think it’s a very important one. In the 1740s, the ivorybill had not yet acquired the mystique that would accompany it from the mid-1800s to the present, a mystique that was popularized if not invented by Audubon. This lends greater credibility to earlier reports such as Kalm’s. I think the same principle supports Jefferson’s listing of the ivorybill as resident in Virginia (which may have been based on his own observations) a couple of decades after Kalm and a few decades before Audubon.
To return briefly to Wilson and another report from an unexpected location, Jackson (2004) references a specimen collected by Wilson from somewhere between Winchester, Virginia and Martinsburg in what is now West Virginia (presumably in the Potomac watershed). I have not located the primary source for this reference, which may be in the archives of the Philadelphia Academy of Natural Sciences, but here’s Jackson’s:
The Putnam County, WV find is also interesting, as it suggests a bird that may have been collected for trade rather than being acquired through it.
I want to touch briefly on two additional records, both involving specimens. The facts related to these records point to how even specimen evidence is not free from ambiguity. For one thing, specimen tags often reflect shipment rather than collection locations. In addition, labels could have been changed and replaced at any point in the chain of custody between hunter and museum.
The first specimen is housed at Cornell (and I have seen it myself). It was collected in 1898 from the “Florida keys”. In Appendix E of the Ivory-billed Woodpecker Recovery Plan, it is suggested that this might actually refer to one of the forested “keys” in the Everglades rather than to one of the offshore islands. However, given the ivorybill’s use of barrier islands on the Atlantic Coast and the 10,000 Islands in Florida, it does not seem farfetched that the specimen could have been collected somewhere in the Upper Keys proper.
From my current perspective, based on the Recovery Plan’s information about habitat on the southwest Florida coast, both possibilities seem plausible and neither is particularly surprising. However, neither location would ever have had many characteristics in common with stereotypical ivorybill habitat – vast, contiguous bottomland hardwood forests. (Although he sometimes seemed to embrace this stereotype later in life, Tanner recognized that ivorybills lived in varied habitats, as have others who have studied the subject in depth.)
The other specimen, labeled as being from Forest Park, Saint Louis, Missouri, escaped Tanner’s notice initially but was included in his 1989 update. It is housed at the Colorado Museum of Natural History in Denver and was collected in 1886. Matt Courtman pointed out that by 1886, Forest Park was hardly an isolated spot; it attracted “hundreds of thousands” of visitors a year,was located on the outskirts of a city with a population of 400,000, had been at least partially landscaped, and was accessible by streetcar.
So not only did this collection come from well north of what’s commonly accepted as the historic range; it may have come from a managed parkland on the outskirts of a major city, hardly stereotypical ivorybill habitat. The location and date are surprising, so it’s possible that the specimen was collected somewhere else (though not in a different region) and that Forest Park was the shipping location.
This may be so, but an 1886 collection from anywhere near Saint Louis is a paradigm-buster, regardless of the exact location, as this 1884 map suggests. Forest Park, to the southeast of Florisant and Ferguson, which are indicated by the red circle on the map, is not shown.
Tanner’s original map showed the ivorybill as never having ranged farther north than the Missouri bootheel (the southeastern corner of the state) and as having been extirpated from all but the southernmost tip of that region by 1880. The last specimen collected in Missouri dates to 1895, from just north of the bootheel “eight miles southwest of Morley.” (Widdman, 1908). Tanner seems to have been unaware of this record, which is mentioned in Jackson, who could not locate the specimen itself.
Tanner received at least one report (1937) from Dallas County, Missouri, which is northwest of Springfield, in the upper (southern) reaches of the Missouri River basin and well outside the generally accepted historic range. The source was a local Audubon Society officer, and the letter is archived at Cornell. There appears to have been no follow-up. According to the Recovery Plan, reports from this general area continued until 1949.
Though his map of the range ca. 1890 suggests a northernmost limit in Mississippi and Louisiana, Hasbrouck (citing Cooke, Bird Migration in the Mississippi Valley) mentioned 1884 records from near Kansas City and undated claims of former breeding near Fayette, along the river in central Missouri; Tanner considered these questionable or accidental. I agree that they’re somewhat questionable but not that they could have been accidental, since both purportedly involved breeding.
Reading Cooke reveals that both were second-hand accounts. The Kansas City report includes no details except that birds were observed “during the past few winters”, and “it probably still breeds in that vicinity”. For Fayette, the source was identified as a local farmer and egg collector by the name of Lientz, but the former breeding claim is devoid of any details, including the informant’s name.
Thus, the possibility of mistake or miscommunication exists in both instances, as in the seemingly credible report from eastern Nebraska discussed in Part 2; however, Jackson also references Harris’s Birds of the Kansas City Region (1919), which lists a “Judge Guinot” and others” for the Kansas City area records, in the “deep woods of the Missouri bottoms”. No date is given, but it seems possible if not likely that Guinot (1855-1935) was Cooke’s source
While I think the historic range probably extended as far as Kansas City, the case seems a little weaker to me than it does for the eastern seaboard and Ohio Valley – given the paucity or absence of archaeological evidence or early reports from the Missouri River watershed, a key route for explorers, traders, and early settlers. For example, Featherstonhaugh, who crossed the Missouri River basin near the confluence with the Mississippi in the 1830s, described the northern limit as being considerably farther south, in the Arkansas-White River watershed. But perhaps there’s more to uncover about the ivorybill’s history along the Missouri.
As with anything ivorybill related, it’s probably best to be comfortable with not knowing and even to revel in the uncertainty.
The previous post generated a number of responses, mostly positive, but there were a couple of negative remarks, one of which I thought I should address.
One claim was that this new way of examining the imagery (which was misleadingly described as “enhancement”) confuses the issue and makes the images harder to assess. In reality, the processes used in the previous post and in this one are for the most part not “enhancements.” While I have used various image enhancement tools in the past, most of these treatments use unaltered original images to create composites that make it possible to separate figure from ground and parts of the target from artifacts. It’s not a perfect method, but it’s an illuminating one, even with low resolution images. It requires no special forensic expertise. As should become clear from this post, it can also be useful for estimating size.
The images examined in this post were all captured December 7, 2014 on a Reconyx Trail cam that was showing its age. They were previously discussed here, here, and here. As in the previous post, I’ve used Luminar to create the composites and apply various effects for this deeper dive. As always, views can be had by clicking on the images themselves; mousing over the images will reveal captions in most instances, and I have added versions with arrows to help orient you. I strongly encourage you to examine the images closely.
One initial comment about these images and the ones discussed in the last post: I’m personally convinced beyond a reasonable doubt that two of those images show Ivory-billed Woodpeckers. The images discussed in this post show fewer details, so they may not be quite as compelling. Either way, the captures under discussion are only part of the mosaic, and the subjective conviction that we have found Ivory-billed Woodpeckers in two locations is not solely dependent on them. The audio from last year, for example, is strong evidence in its own right. Go here for a detailed discussion of evidence gathered since 2009
I’ve reposted the original captures in tiled mosaic form below; I’ll follow that with some composites and comparisons among the images. I think the results are helpful if not quite as revelatory as the ones in the last round. A very prominent American birder tweeted that one of the images below shows a Blue Jay (9.8-11.8″) and characterized the suggestion that it might be an ivorybill as “crazy”. (This is the capture I think is likeliest for ivorybill in this group.) I think his knee-jerk suggestion is absurd, as this approach to reviewing the images should make more apparent.
I’ll begin with the raw image I’ve always liked most for ivorybill, as previously discussed in detail and in comparison with Imperial Woodpecker captures. (Note that the version comparing putative IBWO and IMWO has been enhanced.)
The next image shows the difference between the foregoing frame and one captured approximately 40 minutes later. The bird to the left of the snag is clearly closer to the camera (which was approximately 85′ from the target snag), between it and the snag. The composite strengthens the impression that the suspected ivorybill is behind the tree and the foliage behind it, since at least some leaves appear to be between bird and camera. Frank estimated the foliage as being 15′ more distant.
In the earlier discussion, several Pileated Woodpecker captures, including the one below, were used for comparison. These captures were taken from a slightly different position, but that’s irrelevant to the issue of size relative to the reference object, the jug handle-shaped stub.
It may be even more instructive to contrast the capture with the Red-headed Woodpecker, apparently caught as it was preparing to land on the snag. The comparison suggests that the two birds are approximately the same distance from the camera. The possible ivorybill’s body is considerably longer than the Red-headed Woodpecker’s wingspan (14-17″). Thus, between the Pileated Woodpecker (~16-19″, with southern birds typically on the smaller side) and the Red-headed Woodpecker, it can be inferred that the suspected ivorybill is approximately the right size (19-21″), considerably larger than a Red-headed and somewhat larger than a Pileated. I am unable to think of an alternative ID for a bird of similar size and shape, even leaving aside the fact that a white trailing edge seems to be present even in the original, unmodified version of the capture. (The trailing edge becomes more apparent when the image is processed to reduce motion blur.)
A different but related method of image processing is helpful for understanding the position of the bird relative to the snag and also suggests that another capture in the series is at least size-appropriate for ivorybill; the tuck and the long, pointed shape of the wings are also intriguing. The first composite shows the unknown bird and the Red-headed Woodpecker. (Note what seems to be a wing, species unknowable, protruding from behind the snag; it appears in the Red-headed frame and no others and had gone unnoticed until now. On looking again, this could also be a squirrel’s tail, albeit unusually positioned.) The second is an overlay of the suspected ivorybill capture and the unknown bird processed using Luminar’s “Color Burn” feature; the two birds appear to be approximately the same size and in the same plane. I’ve added a shot of a Pileated Woodpecker in flight, with wings in a similar position, for comparison.
Another capture from the morning of December 7 has always interested us. The underwing pattern and shape are suggestive of ivorybill and reminiscent of one of the Singer Tract photographs. But questions about size have lingered. Comparing this image with two others from the same deployment that show Red-headed Woodpeckers may be helpful, and it has pushed me toward favoring Ivory-billed Woodpecker for this capture as well.
This capture seems more ambiguous to me, but a few factors are more consistent with Ivory-billed Woodpecker than Red-headed Woodpecker. Both Red-headed Woodpeckers, one captured on the same morning under similar lighting conditions, appear to be closer to the camera than the possible ivorybill. My efforts at measuring wingspan were crude, but the suspected ivorybill seems to have a slightly greater wingspan, despite the upturned angle of the wings and apparent greater distance from the camera. This would tend to exclude Red-headed.
The comparison is also useful insofar as it shows that the wing and body shape of the possible ivorybill are not similar to the Red-headed Woodpeckers captured during this deployment. While Red-headed wing and body shapes can resemble ivorybill at certain angles and under certain lighting conditions, as Bill Pulliam documented years ago, the tail in this image looks too long relative to the body, and the wings look very narrow, at an angle that I don’t think would create an illusion of elongation.
As always, I’m open to correction, and my interpretations are provisional. Intelligent and informed comments are welcome.
I’m making another departure from my posting schedule for reasons that I hope will be self-evident. This is the strongest statement of my views I’ve made to date; I’m calling it as I see it based on this new way of looking at the photographs. As always, click on the images for better viewing.
A Louisiana photographer (and new Project Coyote member) who has been following our efforts, reached out to me in response to the recent trail cam capture and alerted me to a feature in Photoshop. This feature makes it possible to stack two images and subtract the identical pixels, leaving the differences between the two images visible in the new composite.
I understand that this is sometimes referred to as subtracting and sometimes as ghosting. Given my limited knowledge and skill set when it comes to image processing, this was a revelation. The method is described between minutes 1 and 2 of this YouTube video. (The rest of the segment pertains to image stacking for landscape photography and is not relevant to this discussion.)
He sent me three examples – the recent capture, the neckbird, and a pair of photographs showing what Frank Wiley had identified as a female Ivory-billed Woodpecker in flight. I didn’t get any new insights from the last of these; the results for the most recent capture were interesting and possibly significant; the neckbird was a revelation, eliminating any lingering misgivings I had about the image and convincing me (at least) beyond a reasonable doubt that it shows an Ivory-billed Woodpecker.
Bear in mind that the images discussed below are among a handful of captures (out of well over a million images obtained since 2009) that we’ve found to be suggestive or better. (At the 20 second interval used on our current cameras, a single month’s 12 hour-a-day deployment will produce over 60,000 images; the Reconyx cams had a 30 second interval, but that’s still over 40,000 per camera per month.) So it’s not as if we’re finding possible ivorybills everywhere, let alone frequently.
I recently started using a different, ostensibly more user-friendly, image-processing program, Luminar, and I found that it has the same capacity. I tried it on the other oft-discussed trail cam capture with the same revelatory result, although in that case, I did not have access to both unprocessed originals and had to use one cropped image and another that had been cropped and lightly processed for brightness and contrast. I don’t think this impacted the results. I used Luminar to process all the images discussed below.
Immediately below is the original “Neckbird” capture and an enhanced crop, followed by the processed image, showing the difference between this frame and the one before it. Next is a detail, showing the ‘ghost’ outlines of the image that appeared in the original. (Note that a second bird may be present in the form of a bill protruding from the lower cavity in the snag at right, as discussed in this post.)
For me, the most startling result is that the bird looks even more serpentine and elongated in this iteration. This is mostly because the lower third of the body (apparently including part of the tail) is better resolved and distinguishable from surrounding objects. What I had thought was a patch of white near the base of the bird, just above the lower diagonal branch, turns out to have been a leaf. I think this longer, leaner profile is inconsistent with Pileated Woodpecker and consistent with Ivory-billed Woodpecker, and not just because of the neck, the feature that was most suggestive to many who viewed the original capture. I’ve seen a lot of Pileateds and have looked at countless images online, and nothing about this better-resolved silhouette suggests Pileated. The remnant clips from the 1935 Ivory-billed Woodpecker film may be illuminating in terms of neck and body shape.
The silhouette in the November 30, 2009 capture, which was the first suggestive image we made public, is not as compelling as the one in the image shown above, but the capture shows three apparent ivorybill field marks – a black crest, white on the lower part of the bird, and a large, light-colored bill. In this case, the processing provides additional information about these apparent field marks. The bird also appears to be larger than a Pileated Woodpecker. The basics of all these issues are addressed in Frank’s original discussion of this capture.
To reiterate, I am not in possession of the original frame that follows the capture. It was probably lost after Frank’s passing, so I used two crops for the first composite, one showing the suspected ivorybill and the other, the subsequent frame. The crop of the empty frame was otherwise unaltered, but the one with the bird had the brightness and contrast adjusted. The output differed slightly between the “difference” version and the “subtraction” version, something I did not observe when working with unprocessed images. The difference, however, appears to be limited to background features and not the bird.
Remember that this capture was obtained from a spot where I’d had a sighting of a large woodpecker with a lot of white on the wings on the 25th . Both Frank and I heard the wingbeats, which were loud and distinctive. This was a rare instance in which a bird appeared to have been brought in by a double knock series. We’d also had an auditory encounter about 300 yards away on the morning of the 24th, while staking out the cavities in the willows shown above.
The first image shown below is the original capture with the red box around the bird. The crops appear as a pair of images. The first shows the bird, and the second is the subsequent frame with the bird absent. Those are followed by the difference and subtraction composites. More discussion after the images.
As I read this imagery, I think it suggests that the apparent white saddle is part of the bird, not light leaking through or an intervening object; indeed, the intervening branch is revealed in the ghosted images, with the body of the bird still visible behind it. That said, this may be the most ambiguous aspect. The treatment also highlights the presence of the crest and shows it is part of the bird; there is no red in the original; if any red were present, it should be at least faintly visible at this range and under these conditions. This interpretation is based both on the color in the background and on a Pileated captured perhaps six feet farther from the camera during this deployment (in an overexposed image included in Frank’s original analysis).
Most important of all is the fact that both the difference and subtracted versions confirm that the apparent very large bill (which appears to be light-colored in the original picture) is indeed a bill and not some other object. Even allowing for some motion blur, the bill is disproportionately large and therefore inconsistent with Pileated Woodpecker. Indeed, all discernible features in this photograph are consistent with female Ivory-billed Woodpecker and nothing else. I have always believed this picture showed an ivorybill. Based on these composites, I am now firmly convinced that it does.
I also tried creating a composite combining the capture, which was taken in the late afternoon of November 30, 2009, with another frame taken in late morning on the following day. The results are somewhat less distinct but the same elements are still apparent.
Finally, I tried this approach with the images discussed in the previous post. The results of this effort were somewhat less satisfactory. I assume because the originals are lower resolution and therefore contain fewer pixels. Lighting conditions may also be a factor.
This capture offers a lot less to work with. The Reconyx jpegs are 2048 x 1536 or 3 megapixels, while the Plotwatchers are 1280 x 720 or less than 1 megapixel.
I was unable to find additional specifications for the Reconyx cams, but the folks at Day 6 Outdoors were kind enough to provide them for the Plotwatcher. Per Day 6, the sensor is .25″ (which is smaller than most cell phone cameras); the focal length is 3.5 mm (which I think translates to the equivalent of an ~20 mm lens on a full frame or 35 mm film camera); and the aperture is f/2.6 (apparently the equivalent of ~f/16).
Nevertheless, I experimented with using both the original captures and versions enlarged using Topaz A.I. Gigapixel. I applied the same process to the squirrel capture from a few weeks earlier, which was taken under better lighting conditions. The relevant images and discussion are below, starting with an enhanced version of the original capture with an arrow pointing to the object of interest. Remember that the silhouette that resembles the head and neck of a woodpecker is background vegetation. The object of interest is the small bit of black and white below it.
As mentioned, I’m less confident about interpreting the results for this image, since so much less detail can be gleaned. Unlike the other captures, the subtraction or ghosting does not reveal a clear outline, and aspects of the object which are distinct when moving from frame to frame are obscured in this treatment. Also note the near absence of difference between the preceding and following frames.
In the enhanced iteration, a little more of the outline of the putative IBWO may be visible. I suspect that the reason the white saddle does not appear uniform in this one is due to pixels and that the dark patch below the bright white band is consistent between images because the foreground and background pixels match, not because they’re the same. This explains why the bottom part of the saddle, where the wings meet, is also white. In other words, these are the places where the object was in front of darker pixels. That’s my guess based on shifting back and forth between the relevant frame and the ones before and after. In addition, the white dots above the “saddle” may represent dorsal stripes.
Things change slightly when using imagery from different days. I’m only using the enhanced versions here, but they again strongly suggest that the white saddle is part of the object, not the background. The second frame is the one that follows the squirrel capture discussed below.
The squirrel capture may provide some additional insights into the process’s limitations with lower resolution images. The squirrel, which is clearly visible in the original image, shows up as a narrow strip that’s easily missed if you don’t know it’s there. The second version is a composite using images processed through Gigapixel A.I.
Weather and lighting conditions differed considerably between the two days in question. The camera was pointed in an approximately easterly direction, probably more ENE or NNE; lighting conditions may account for the fact that this image is a little lighter and some small differences are more apparent from this pair of captures. The weather at the nearest station at the time of the squirrel capture was fair with little to no wind; whereas the weather for the putative ivorybill capture, which was taken in the afternoon, was intermittently stormy with winds probably around 10 mph. Under stormy conditions with foliage moving in the wind, there should be more variation between images, not less, so available light seems a likely factor perhaps in combination with number of pixels.
Thus, I’m not sure how much this process adds when it comes to interpreting the most recent capture and how useful it might be with others from Plotwatcher trail cams. (The two older images were taken with a color Reconyx.) But I hope that the cameras are now deployed in such a way that enhancement and differentiating won’t be necessary.
While the approach does not reveal much when it comes to the new image, I think it is dispositive with regard to the old ones. Of course, I make no claims to expertise in forensic image analysis or the technical aspects of image processing, so I am open to being corrected if any aspects of my analysis are flawed.
Like most searchers, I have tended to focus on whether the evidence is sufficient and have seldom thought about what obtaining conclusive documentation might imply. If the two images from the old search area are ivorybills, a number of questions emerge. So let’s assume (or assume arguendo if you are unpersuaded) that these images indeed show Ivory-billed Woodpeckers:
As an initial observation, if I am right about the two captures, I think it becomes overwhelmingly likely that the apparent bill protruding from the cavity in the background of the neckbird image also belongs to an ivorybill, so it seems probable that least two birds were present in the area in 2009-2010. This is consistent with what six of us heard during an auditory encounter in January 2010. One of Frank’s sightings involved three birds. (He was accompanied by the landowners’ teenaged grandsons at the time.) This sighting suggests that breeding might have taken place in the area.
The habitat in the immediate vicinity of the camera trap deployments is not what has been thought of as having much potential; the quality is even lower than I realized at the time. I knew a lot less about forest ecology and conditions in 2009, and while I certainly recognized the habitat as not “optimal” back then, I think I overestimated and perhaps romanticized the overall quality.
Both captures come from within 50 yards of a bean field. The woods in the immediate vicinity did have a number of large trees, and there are good sized cypresses in the area, but the parcel and the neighboring ones (including the one that was clearcut) are not particularly old. Back then someone indicated they’d been cut in the early 1960s.
The site of the earlier trail cam pic and our November auditory encounter is .6 miles from a large parcel of state land that has some very mature forest and inaccessible areas. (The location of my November sighting and the second trail cam capture is approximately 300 yards farther east, away from the public land.) Several other large parcels of public land are within a few miles of the area, so it’s not exactly a suburban backyard. Nevertheless, it’s a far cry from the Singer Tract or our current search area for that matter.
It seems to me that if one accepts that a pair of ivorybills was present in this location in 2009, there’s no basis for doubting the landowner’s claim that birds had been present and using the area for a decade or so. It also supports the idea that audio obtained there included ivorybill kents and double knocks, which tends to validate audio captured elsewhere – Arkansas, Florida, South Carolina, and our current search area.
How does/would the confirmation of ivorybill survival, especially in such ostensibly low quality habitat, impact the assessment of other reports?
Why is that ivorybills are being reported in so many different places over the last two decades? Is it just more publicity, or is something else going on?
Why aren’t there more reports from the public and from experienced birders?
Why are they so hard to document? Even if you read the Project Coyote trail cam captures in the most liberal possible way, there are no more than a handful of images that I think of as likely, out of well over 1,000,000.
Where does one look for them, especially if they are using habitat always thought of as unsuitable?
What is suitable habitat?
What kind of population is out there and how has it sustained itself for so long?
I’m sure there are more, and I don’t have good answers for most. I think the technical limitations of trail cams, scarcity, and wariness (even run-of-the-mill or somewhat overdeveloped wariness) are probably adequate to explain many of the documentation issues but perhaps not the relative paucity of sightings.
I hope to return to my planned posting schedule with the post on range in a week or two and the one on evidence a couple of weeks after that; however, I’ve been looking at composites created from the Reconyx images discussed here. I think the results illuminating with respect to size. This post is already long, so rather than include them here, I will likely do a follow-up examining those images before turning to more general ivorybill-related topics.
Best laid plans . . . I’m pushing back the posts on historic range and evidence but hope to get to them soon.
In going through some of the remaining unexamined images from past trail cam deployments, Geoffrey McMullan came across an intriguing image. He sent me the file for the entire day without indicating where the image was located or what interested him about it. Reviewing cards is challenging; it’s tedious, while demanding focus and attention to very subtle changes. It can be easy to overlook hits of any kind. Nevertheless, this particular frame leapt out at me immediately, even though the object involved is indistinct and is only present in a single frame (more on that later).
I’ll begin by sharing and discussing the image, before and after stills, a time lapse video, and some additional captures comparing other animals with what’s shown in the frame. I’ll follow that with some of the discussion that has taken place among the active searchers in our group and some of the biologists who are advising us. Matt Courtman suggested that everyone on our email list give three reasons they like the image for ivorybill and three counterarguments. Not everyone followed the suggested format, but I’ll draw on those emails as well. I’m hoping this will give you some insights into our process and also give you some additional ways of looking at the image, which I believe to be a picture an Ivory-billed Woodpecker, even as I recognize that it isn’t nearly good enough to stand as proof.
I’ve done my best to present this material in a clear and careful manner. This is not an image that lends itself to immediate, easy interpretation, as some of the discussion reveals. At the same time, a lot can be gleaned from a close, careful look at the raw image, and the preceding and following frames. The various enhancements and comparison captures provide additional context.
A further caveat: I write this blog to maintain a log of our efforts and to share our results with readers on an ongoing basis, in an honest and transparent manner. As with any scientific endeavor, our search is in a constant state of flux. Everything is subject to change and reappraisal based on the evidence. We offer this image with that as background. Most of us believe subjectively that we have found an area that is used by Ivory-billed Woodpeckers, at least periodically. We all recognize that we do not have enough objective “proof” to “convince” third-parties that this is so. The subject image, so far, is just an intriguing part of the mosaic. It’s up to you to decide whether it moves the needle toward “proof” in your mind.
The image was captured on July 12, 2017. The target tree is a hickory that lost its top in a storm in March of that year. And we’ve had a camera aimed at it ever since. This is in area where we’ve found extensive scaling on hickories over the years and where we’ve had a number of auditory encounters. It is within the same contiguous forested area, several miles from the site of the March 2017 recordings. While squirrels are frequently captured on the target stub, there have been few woodpecker hits, and there was no obvious foraging sign on the trunk when I last visited in June.
Perhaps the most informative way to view the image is to step through the time lapse video frame by frame and compare the before, during, and after images. (You may have to download the clip to do this.) This will help clarify what’s object and what’s background. If you’re having trouble downloading the clip (and associated comparison clip), contact me, and I will share the files via Dropbox. I encourage you to click on the individual still frames to see larger, zoomable versions.
Here are two versions the relevant capture, one in its original, unprocessed form and another with a Luminar vividness filter applied, sandwiched between unprocessed captures from 20 seconds before and 20 seconds after. The arrow is pointed at the object of interest.
Here’s the time lapse video clip.
Here is a version of the still, resized using Topaz A.I. Gigapixel, an automated, artificial intelligence-based, image enhancement program. Following that are two enhancements, and a detail therefrom, made using another processor, Let’s Enhance. Both of these programs are automated, so except for selecting enlargement percentage and general processing parameters, I had no influence on the resulting images. Note that the prominent silhouette, which suggests a woodpecker’s head and neck, is blurred, background foliage, not part of the object. Assuming that the object itself is an ivorybill, I think the capture suggests the bird is angled slightly away from the camera, with head and neck inclined to the right.
Edited to add: A significant number of readers have misinterpreted the image, despite my explanation. To reiterate, the somewhat woodpecker head and neck-ish silhouette is background vegetation. The object’s head and neck are not visible. This detail, scaled up as much as possible, should be helpful, despite the loss of resolution.
Next are a squirrel and a presumed Red-bellied Woodpecker (9-11″ including head and tail) captured on a different day. They are included for scale. Both are a little lower on the trunk and are therefore closer to the camera. The captures are followed by a 50-frame Quicktime clip showing both the smaller woodpecker (suspected RBWO) and some squirrel activity. The comparison suggests that the object, which appears to be perched in typical woodpecker fashion, is too big to be a Red-headed Woodpecker (8.3-9.8″ including head and tail) and is slightly larger and more substantial than the head and body of an Eastern gray squirrel (9.1-12″). No tail, head, or neck is discernible, so the size of the object is in the appropriate range for an ivorybill body. (Total length is given as 19-21″ with tail at 5.5-6.7″ and bill at 2.3-2.9″) More discussion, including my responses (in italics) to some questions and comments (in bold and italics), is below.
An ornithologist wrote:
. . . I have tried every possible way to call that something other than ibwo but I can’t make it into anything else. The general impression of size and shape and even posture / body position relative to the tree is spot on.
And then in response to my explanation about the foliage that had caused some confusion:
I was seeing body only, folded wings white patch.
Early on, I had the following exchange with another biologist and ivorybill researcher:
Interesting. First, as I said before, I am no expert on trail cam photos like these. It looks like a black and white object for sure, with white on the bottom, but to my eye it is not possible to determine what kind of object it is. For sure, a bird would make a lot of sense. And if it is a bird, given the location, and pose on the trunk, a woodpecker would make a lot of sense. I am not sure if I see white at the top of the object as well?
How big is the tree that the object is sitting on, and is that scaling on the other side of the tree or remnants from when a branch that broke off? Have you seen bark scaling in that neighborhood?
I’m pretty sure that it’s a bird and therefore a woodpecker.
I think I see a white saddle and possibly a dorsal stripe. I also think it is too big to be a Red-headed, based on the squirrel and on a smaller woodpecker that’s on the trunk in another frame from another day; I’ll have to find that image.
The tree is a large hickory stub. What looks like scaling is where bark came off when the top fell. It is in an area that has had a good concentration of hickory scaling over the years.
If you have software that enables you to step through it frame by frame, the movie clip can be very informative. Flip Player is an easy one to use.
Thanks. I just looked at the entire series step by step with Quicktime and it is very intriguing. One question: could some of the white (or all of it) actually be sky in the background? The other frames show sky in the same location. I am not saying that it is, just trying to rule out possibilities.
My answer (another person raised a similar question):
I don’t think so. To my eyes, it’s pretty clear that the white is on an intervening object. I think the white on the object actually covers some of the dark area (as well as the lighter patch) behind it in the preceding and following frames.
And the conclusion:
Good. It is a very intriguing picture.
There was also this exchange with a consulting biologist:
If it’s okay with you, I may include a version of the comment in the blog, anonymously of course.
I can’t prove a negative, but I’d bet my bottom dollar that it’s not a squirrel.
Sure, no problem. But let me add the following.
What are the chances of a large woodpecker kind of critter showing up all of sudden in one frame and no sign that it either flew in or left or was in view beyond the one frame 20 seconds or anytime later.
An alternative could be some other sort of critter ( apparently larger than gray squirrel, perhaps fox squirrel, possibly raccoon) that worked up from the ground up the tree and then went back down out of view of the reconciliation.
As you said can’t be sure this is even a woodpecker or any other bird.
Beyond all that, still “interesting” but how many times…
I had one point of disagreement:
I mostly agree – with one quibble. It’s not unusual for birds to show up in a single frame and no others (the probable RBWO in the other clip, for example); it’s much rarer and (more difficult) for mammals to do so.
My correspondent recognized the quibble as a fair point, and it bears repeating that there have been very few woodpecker hits on this tree, probably because it is very recently dead. This exchange also led me to suspect that some of my colleagues were thinking the background foliage was part of the object in question. The discussion ended with this observation:
You are right Mark, I was interpeting the background veg as looking like the neck and head, which really made me wonder why so faded. However, now we have a frame 33 of the Luneau Video situation.
Anyway, thanks for the re-orientation.
Another member of the group also mentioned Luneau, and the similarity is striking, although there’s no accompanying video, and this single capture seems to show more than the Luneau frame.
1) first the obvious, I can’t tell much from the original picture other than it is long and somewhat “thin” relative to more stocky animals. Based on the zoomed in picture, however, it is a live bird; I can see no way it was photo shopped or that it was placed there as a wooden (or otherwise) replicate. I think it is easy to dismiss any attempt at faking it.
Definitely no fakery here 😉
2) The zoomed in image is impressive, it certainly appears to have a white back (which is a slightly different color than the white of the sky next to it) and I see what appears to be two white stripes on the back as well. The comparison of a probable RBWO on the same tree is noteworthy and clearly shows the relative size of the bird in question.
I think the size comparison stands regardless.
Negative concerns –
1) Any of the above positive impressions may be a function of zooming in well beyond the camera’s ability to correctly interpret what’s really there.
Actually, I think that it’s somewhat more compelling unaltered, if you can toggle.
3) The only one frame concern ****** brought up . . . . . . while I don’t think this is a squirrel or mammal of any kind and I’m not at all concerned about this particular series (see below), I am puzzled that the bird in question would not have shown itself on other occasions as well. Are there any pictures of this tree with a PIWO on it? How many pictures (days) do you have images from this camera on this tree? Is the primary foraging area on the other side of the tree? I’m assuming you have several days in not a few weeks worth of pictures on this tree (?)
The camera has been there for over a year, and I’ve gone through countless images. No other suggestive hits. Lots of squirrels. I don’t recall specific PIWO hits on the target tree, although there may have been some, and I’m sure there were at least a few from the deployment. This is one of the targets that has no scaling on it as yet; visits from woodpeckers have been few. As with the RBWO, I suspect birds may be hitting the tree in an exploratory manner at this point and are not staying long.
Just FYI . . . .This is [not far] from where we saw the bird that I ended up thinking was a RHWO and that you weren’t quite so quick to give up on, closer to where I had the long neck and tail silhouette sighting after some ADKs.
An additional note about not concerned about this series and only one frame . . . . .I feel strongly that IBWOs are incredibly wary, much more than we have been assuming them to be. And as any resident bird, it knows its territory very well and that anything “new” or different in that territory could spook it. I hunt as you know, and can vouch that turkeys and waterfowl are often that way . . .one thing out of place from the normal and they leave . . .
With that said, I wouldn’t be surprised, if this is an extremely wary IBW, that it knew something was not quite the same in the area and stayed on the far side of the tree on purpose . . . Even as I type it and re-read it, it sounds a little crazy but since I know about that level of wariness in other species I take it seriously. I know the discussions about wariness and “Tanner’s birds” etc but not sure birds now would act the same way as birds 60 – 80 years ago. If they are that wary, then that also has implications to where the camera is moved. It has to be close enough for a good picture but far hidden well enough to not spook the bird. (If you talk to Tommy or others about new deployment of the camera, my thoughts about how the wariness of this bird is pretty well known and doesn’t have to be anonymous).
I’ve wondered about this myself, and it seems like a pitfall when it comes to putting cameras very close to target trees. With time, however, I suspect birds would become habituated. It’s always a trade-off with these cams, and unfortunately, they have to be placed quite close to the targets.
Thanks for keeping me in the loop Mark – all in all, this has the most “real” field marks and most potential of anything I’ve seen.
I really do think it’s an IBWO . . . it’s at least more cause for optimism and grounds for staying with the trail cam strategy. As I’ve said, I think we’re finally in a position to do it right.
Here’s the response:
Thanks for more clarification Mark – yes I did toggle back and forth, now that I’m not so worried about what I thought was head, neck and bill, the unaltered is more intriguing.
Good to know its been there a year, I agree that birds will get used to it being there over time. The picture has July 17 2017 along the bottom, is that correct or is it July 2018?
I also forgot that this was a tree that you were interested in before any scaling started . . . .that’s pretty exciting and would explain my other concerns about infrequent use and no PIWO use. Pretty exciting in that (if a 2018 picture) the best is yet to come for woodpeckers. Regardless of IBWO, keeping a camera on this tree and having a sequence that shows which woodpeckers use tree, when and how (assuming there are differences based on tightness of bark etc) would be cool from that area.
Frankly, as I was looking at the picture(s), I thought a few times “Damn, I think he got it” . . . . . . Thanks again,
The picture is indeed from 2017. But there’s no scaling on it as yet, so it’s worth staying with.
I hope these exchanges help to illustrate some additional challenges related to trail cams, while revealing something about the review process. I think the object in question is an Ivory-billed Woodpecker; so do some of my associates. It’s not proof beyond a reasonable doubt, but it is an encouraging and suggestive piece of evidence.
I’m still planning a post on historic range and one on questions of evidence but thought I’d take this brief detour first. Tommy Michot is braving the Louisiana summer to change batteries and cards and to deploy an additional trail cam. We’re trying to service the cameras and replace the cards on a bimonthly basis. If there’s anything noteworthy on the cards, I’ll adjust my posting schedule accordingly. Look for the historic range post within a couple of weeks and the one on evidence a few weeks after that, before the start of search season in October.
This is the first time I’ve devoted an entire post to someone else’s effort. Though I’ve received a number of other intriguing reports, I’ve chosen to write about this one for a couple of reasons. First, I want to counteract the oft-repeated notion that reports have dried up in areas where intensive searches have taken place. Second, the searcher in question has found intriguing feeding sign as recently as 2017. The images included in this post are among the most suggestive I’ve seen from outside our search areas and tick most of my Ivory-billed Woodpecker boxes. I use the word ‘among’ advisedly here, since virtually all the feeding sign imagery that I’ve found intriguing comes from the Choctawhatchee, including the images showing extensive work on this page from the site devoted to the Auburn search.
The source of the report is an experienced birder and photographer named Rick Sellers. He has generously agreed to my posting this and allowed me to include some of his photographs. His first sighting was in 2012, approximately four years after organized searching came to end in the area and approximately seven miles downstream from Auburn’s ‘hot zone’. Rick shared the details with his family members and with Geoff Hill at the time and posted his email to his family on ibwo.net in March, 2014:
No doubt about it! While in the swamp today, I heard a large woodpecker hammering in the direction of a stand of slash pines at the edge of the swamp. I headed that way and just as I entered the clearing I saw the silhouette of a large dark bird leaving a tall tree on the other side of the stand of pines. I couldn’t ID it because the overcast sky was too bright. All I saw was the dark silhouette against the sky but the bird was clearly larger than a pileated woodpecker and flew loon-like, not undulating like a pileated. There had been a fire in recent years in this area and about 50% of the pines were dead showing extensive bark scaling, diagnostic of ivorybill foraging. Lamenting the fact that I had been unable to ID the big bird, I decided to stake out the pine stand, hoping that an ivorybill would return to feed. I found a secluded spot on the edge of the pines next to the swamp, sat down and ate lunch. I sat there for about 45 minutes and then as I was feeling rather drowsy, lay back with my head on my daypack. I was about to doze off when I heard, “kent-kent” coming from the swamp to my right, no more than 100 feet away! Thinking I must have been dreaming, I sat up and listened intently. Then I heard it again, “kent-kent-kent…..kent-kent! Over the next 3 or 4 minutes, I clearly heard 15-20 kents, some louder than others, that sounded exactly like Dan Mennill’s recordings from 2007. There was no doubt in my mind that I was hearing at least one, if not two, Ivory-billed Woodpeckers! Then as suddenly as they started, the kents stopped. I waited about 5 minutes before moving and then walked into the swamp in the direction of the kents. Unfortunately, I neither saw nor heard anything more as I walked around the area from whence the kents came. I plan to go back tomorrow bright and early and stake out the pines again. (end of email)
Since that encounter, I have been back to the Choctawhatchee at least 10 times for a week at a time. I have hiked and kayaked many miles but have had no more encounters. I am not discouraged, though. Just that one encounter is enough to keep me going until I can get the video or photo of the bird.
Rick informs me that he has had one possible sighting since the time he posted – a large woodpecker showing a lot of white – but that his confidence level is only around 50%.
Rick suspects that the birds do much of their feeding in upland pines outside the floodplain, which is where he had his sighting. He shared a couple of images from the location of his sighting with the notations showing the bird’s path.
Some of the scaling in this stand of pines is extensive, but none of it strikes me as being beyond the capacity of a Pileated Woodpecker. On its own, the work shown in these images would be unlikely to pique my interest. But as in our search area, fire killed pines in surrounding uplands are, at least potentially, a major food source.
What really captured my attention were a couple of photographs. I found the first on Rick’s Facebook page. It was taken in 2017. The tree may be a tupelo, but I’m not sure. The bark is thin, and regardless of species, it is undoubtedly weaker and more easily scaled than hickory. There are also some hints of layered removal, akin to blonding. Nevertheless, a number of characteristics suggest Ivory-billed Woodpecker to me – the mostly clean edges, the lack of damage to or excavation of the underlying sapwood, and the targeted expansion of already large exit tunnels. This is unusual work, and it’s what inspired me to reach out to Rick for more information.
Rick subsequently shared images of a scaled spruce pine he found in 2017. And while I’ve generally taken the view that there’s no way to recognize Ivory-billed Woodpecker work on conifers, this sign is strikingly similar to the work on hickories that we’re finding and also to the work of other Campephilus woodpeckers. The work is very extensive; there’s virtually no blonding or damage to the sapwood, except for targeted digging around the exit tunnels. It ticks my ivorybill boxes, save for the fact that it’s on a softwood and there was no chance to examine the bark chips. The final image below is a detail from one of our hickories for comparison.
Except for a passing claim on Facebook about recent ivorybill sightings along the Pea River (a tributary) in Alabama, I’m not aware of other reports of sightings or auditory encounters in the area, but the fact that Rick has continued to find suggestive feeding sign, as recently as last year, suggests to me that the Choctawhatchee merits more attention than it has gotten since Auburn left. Of course, the same is true of many other areas, but this is the only instance where I’ve seen feeding sign that I strongly suspect is the work of Ivory-billed Woodpeckers. If I were looking for a place to search, the Choctawhatchee would be at or near the top of my list.
Updated – Emerald Ash Borers and Blonding: A Large Body of Bark Scaling Evidence Tends to Rule Out Pileated Woodpecker as The Source of Scaling on HickoriesPosted: July 11, 2018
A couple of initial housekeeping notes: I still plan to do a second, more conceptual post on ivorybill evidence, one on historic range, and possibly another on non-IBWO trail cam imagery. Look for those over the course of the summer. I thought this subject should take precedence and have changed plans accordingly. The photographs (other than my own), which I’m including in the largest possible sizes, are courtesy of bugwood.org (under a Creative Commons License) and Patowmack the trickster.
Thanks to John Kearvell for inspiring me to pursue this subject.
The emerald ash borer or EAB (Agrilus planipennis) is an invasive Buprestid beetle. The first known North American outbreak was near Detroit, Michigan in 2002. Since that time, the species has spread to 33 states and three Canadian provinces.
Bark scaling, especially by Pileated Woodpeckers (Dryocopus pileatus), is one reliable indicator of EAB infestation, and Pileated Woodpecker populations appear to increase as a result of outbreaks. Thus, there is now a large body of data on bark scaling that was not previously available for comparison with suspected Ivory-billed Woodpecker (Campephilus principalis) work.
All of the numerous examples of white or green ash (Fraxinus americana or pennsylvanica) scaling by Pileated Woodpeckers (and presumably smaller woodpecker species as well) found online show “blonding” or removal of bark in layers. This may be due to anatomical limitations that preclude Pileated Woodpeckers from removing thick, tight bark in large pieces. Suspected Ivory-billed Woodpecker work on hickories – which have harder, tougher, tighter bark than ash – shows no trace of blonding or gradual removal. I think this excludes Pileated Woodpecker as the source of the hickory scaling.
Introduction: The Emerald Ash Borer
EABs are believed to have arrived in North America in packing materials. The first outbreak began near Detroit in 2002, and the species has spread rapidly since then, decimating native ashes wherever it goes. All indications are that this invasive insect will have an impact akin to that of Dutch elm disease or chestnut blight, concerted quarantine efforts notwithstanding. Because EABs were a recent arrival and had not been well-studied during the first decade of the 2000s, their relevance to the issue of bark scaling does not appear to have been recognized by the formal searches that were conducted during that period.
While the invasion’s impact has already been devastating, EAB larvae are attractive to woodpeckers, especially Pileated Woodpeckers (Koenig and Liebhold, 2017), and bark scaling is one of the most obvious symptoms of infestation. (This attractiveness may have future implications for any surviving ivorybills as the EAB expands its range.)
Unlike many bole dwelling Cerambycidae, such as Hesperandra polita, which spend the bulk of their lifecycle in the heartwood and do minimal damage to the cambium, EAB larvae live, feed, and pupate just beneath the bark, eventually destroying the cambium. This causes the bark to fracture and sometimes to slough off by itself. In the very dramatic example shown below, I suspect that woodpeckers were involved in most, if not all, of the bark removal but only reached the sapwood well after the bark had started to loosen, fracture, and perhaps fall off on its own. Nevertheless, there are still signs of layered removal on the edges of the scaled/sloughed area.
When I started researching this subject, I was unaware that the term blonding had been applied to woodpecker work in pursuit of EABs, but it has become a widely-used (and apt) descriptive. It refers to the appearance of ash trees or parts thereof, after woodpeckers have started removing the outer bark in pursuit of EAB larvae and pupae. The process of reaching the sapwood appears to be a slow one, and after examining hundreds of images showing of bark scaling on ash trees, I have been unable to find a single example that was devoid of blonding, even when very extensive work was involved.
Patowmack the Trickster’s photo is the most extensive example of apparent Pileated Woodpecker scaling on an EAB infested tree that I’ve been able to find. The tree appears to be fairly long dead – based on the extent of the superficial excavation (tunnels are no longer distinct), the apparent fracture in the trunk at the center of the frame, and on the apparent separation of the bark from the sapwood that’s most distinct on the lower right edge of the scaled surface. While the extent of this work is impressive, I’d suspect PIWO even in potential ivorybill habitat – based on the appearance of the surface, the state of decay and seeming looseness of the bark, and the blonding, which is most evident at the top and at the lower left.
While smaller woodpeckers are responsible for some ash blonding, Pileated Woodpeckers are likely the primary source, especially when the work is as extensive as in the examples shown above. Images of Pileated Woodpeckers on blonded surfaces are considerably easier to find than ones involving other species. This brief video catches a PIWO in the act, on an extensively blonded tree, and points to the difficulty PIWOs face when scaling tight, thick bark.
Blonding on Other Tree Species
I have found blonding or its equivalent on a number of other tree species, so it is not exclusively related to any characteristics of ash bark. Rather, I think it is a function of Pileated Woodpecker anatomy. I have seen this on limbs, including sweet gum (Liquidambar styraciflua) limbs, in our search area and have described it as a “layered” appearance.
It may be possible for Pileated Woodpeckers to remove tight bark from small to medium branches without leaving traces of blonding, especially if the bark is weakened or it comes from a species (like sweet gum) that is relatively soft and thin. Removing thick bark from mature boles is something else again, and I suspect that even when bark has loosened considerably, traces of blonding will often be visible when the work is done by Pileated Woodpeckers.
I have found one extreme example of suspected, extensive PIWO blonding on a bole in Louisiana. I think the tree involved is a sweet gum, but if it is an ash, it would be from a location well outside the range of the EAB today, let alone in 2011 when the tree was found. While blonding is easily visible on the trunk, it can also be recognized by examining bark chips.
I have seen the equivalent of blonding on loblolly pines (Pinus taeda) in the southeast and on softwoods in Westchester County, New York. The bark of most conifers is weaker and less tightly adhering than that of most hardwoods, and it typically becomes easy to scale far more rapidly. This is why I long since abandoned the idea that softwood scaling might be suggestive of ivorybill, unless it involves extensive work on multiple large trees.
I have also found it on live and dead hardwoods in Westchester County, NY. The first pair of images below, which I’ve posted previously, shows fresh, known Pileated Woodpecker work on a Norway maple (Acer platanoides) in my yard. (I saw the bird.) The second pair is from a local park. The snag, which I believe is a large sassafras (Sassafras albidum), appeared to be fairly long dead.
Ash Bark v. Hickory Bark
Ash bark resembles that of bitternut and pignut hickories (Carya cordifromis and Carya glabra), so much so that an arborist mistook the pignut that grows outside my office window for an ash and advised me to monitor it for EABs. Testing bark hardness with a fingernail is one way to avoid confusion. Ash bark feels corky, whereas hickory bark is extremely hard. Last year, I wrote an in-depth post on the characteristics of hickory bark and the reasons it is exceptionally difficult to remove. I won’t recapitulate it here, except to say that hickory bark is considerably harder and stronger than that of virtually any other genus. It is also tighter when trees are dormant or dead, as these reposted tables suggest.
The values shown are for shagbark hickory (Carya ovata), which is slightly stronger, tougher and tighter than bitternut or pignut. While white and green ash bark is considerably stronger and tougher than sweet gum and white ash bark is harder to remove from dead trees, neither species comes close to hickory in any category, except bark tightness when sap is flowing.
I suspect that the extreme strength and toughness of bitternut and pignut hickory bark renders it impervious to blonding. Certain pignuts may be a partial exception, as the outermost bark layer on that species is sometimes slightly subject to flaking. I removed the outer layer of bark from the pignut hickory mentioned above to illustrate; the inner layer is very hard and tight.
Our observations thus far suggest that Pileated Woodpeckers can excavate through hickory bark, leaving behind small pieces, and can remove narrow strips of hickory bark from already scaled areas.
We have found nothing to indicate that Pileateds can go straight from outer bark to sapwood and remove the hand-sized chunks we’ve found under the scaled hickories in the search area.
All of this strongly supports the hypothesis that Pileated Woodpeckers are incapable of scaling hickories in the manner that I believe to be characteristic of Ivory-billed Woodpecker. I’d further argue that the absence of blonding on boles of any hardwood species may be suggestive of ivorybill, provided the bark is thick (over ~.5″) and tight. This is not to suggest that ivorybill work never shows traces of blonding. Though the image quality is poor, Tanner’s Plate 8 may show it.
Something similar to blonding is visible in examples of scaling by other Campephilus species. Thus, an absence of blonding on scaled hickory boles may be a basis for rejecting Pileated altogether and may be suggestive of ivorybill when other tree species are involved.
On a recent visit to a park in Orange County, New York, I found many EAB infested, blonded ash trees. I only had my iPhone with me, but I took some close ups and one shot of the chips on the ground. I also collected some chips and photographed them at home. One of these chips was particularly interesting; while it include some of the outer bark, most of it was from an intermediate layer, further illustrating how the bark is flaked off and that multiple events of stripping are involved before the cambium is exposed.
Evidence collected by Project Coyote in two parts of Louisiana from 2009-2018 should, on its own, suffice to justify maintaining the Ivory-billed Woodpecker’s current listing as an extant, endangered species in the United States. Others may differ, but I think the totality of the evidence does even more, making a compelling case that the species persists in more than one Louisiana location.
This will be a two part post. The initial impetus for writing it was a conversation I had with Erik Hendrickson about how the scientific, birding, and legal approaches to evidence seem to differ. That will be the main focus of Part 2. As for Part 1, after talking to Erik, I realized that I’d never done a single post aggregating the evidence we’ve obtained over the years, so when it was announced that the U.S. Fish and Wildlife Service would be conducting a status review for the Ivory-billed Woodpecker, the need for writing this up became more urgent. That’s the primary focus of Part 1, but some of what I’m planning for Part 2 will be foreshadowed in this lengthy treatment.
There is a strong tendency to privilege visual evidence over other forms – audio and circumstantial. I’m inclined to think that our audio evidence is the most compelling material overall; as regular readers know, I also think circumstantial evidence, feeding sign in particular, is very important. But the structure of this post will track conventional attitudes, starting with visual material followed by a discussion of sound recordings and auditory encounters, and concluding with more circumstantial forms of evidence.
Project Coyote has been focused on two areas in Central and East-central Louisiana. I found what I call the “old” search area after reading a newspaper account of a local landowner’s efforts to get his reports taken seriously. This is the landowner who sketched corrections to the Louisiana Hunting Guide’s ivorybill illustrations and who showed Frank Wiley (my late collaborator) bark scaling when he visited the area.
To be clear about what he was trying to show in the corrections: the gentleman died before I had a chance to meet him, but as Frank told me after his August 2009 interview, all of the corrections are in red ink, so the intent was not to put a male crest on a female bird; it was to show the female’s crest as more erect and recurved than the drawing and indicate that the male’s crest also is more erect and prominent (less Pileated-like) than the game guide representation. Also note the drawings at top right, in which he compared IBWO and PIWO wings, implying that the wings in the game guide image are a little too rounded.
What’s most salient about these observations is not whether they are perfectly accurate, although they do seem to reflect some little-known nuances, it’s that the landowner had enough claimed observations of male and female ivorybills to recognize subtle differences and to distinguish them from Pileateds. In addition, he was offended by the treatment he received when he tried to alert the authorities. I have personal knowledge about this last aspect based on conversations with family members who wanted to see him vindicated.
He was certainly convincing enough for Frank to start visiting the property on a weekly basis during the summer of 2009. Thus, Project Coyote was born.
The landowner’s reports go back to the 1990s. (The linked post includes audio from 2009). There are several medium to large state WMAs and National Wildlife Refuges in fairly close proximity to the site. We heard additional claims from residents of the area while we were focused there.
Putative ivorybill activity on the property seems to have diminished or ended altogether after an adjoining parcel was logged in late fall 2010. As a result, we gradually shifted our attention to the new search area.
The old search area received minimal attention during the post-Arkansas period; some peripheral Ivory-billed Woodpecker-related research was conducted in the general vicinity, but there was no formal, funded search effort. Nor was it visited by Cornell’s Mobile Search Team, although Martjan Lammertink did spend several days on site, after the logging.
Similarly, our “new” search area was entirely off the radar. It doesn’t show up on anyone’s list of promising locations, notwithstanding the fact that it is in one of the most sparsely populated, heavily forested parts of the state. There’s also a long history of local reports. Most of the claims seem to have been fairly recent, but some go back to the late 1990s.
And these are only the claims I know about . . .
For reasons that I hope will become clear, I have not kept track of all our possible sightings since 2009 and have not always mentioned them in blog posts. Nevertheless, I’ll begin with sightings. Over the years, Frank had more possibles and reported having better views than anyone else. I’m probably second, with approximately six since 2009, but unfortunately no good looks. Steve Pagans has had several possibles; a few visitors have also made claims.
While this is largely a subject for the next post, it’s well-known that eyewitness testimony is unreliable, at least when the source is an untrained observer. Nevertheless, eyewitness testimony is central to many a criminal trial, and it has a strong impact on jurors. There seems to be a parallel with respect to the ivorybill. Accounts of possible sightings tend to attract more interest than many more substantive and important posts.
Thus my Sunset Sighting post, which is not quite two months old, has had approximately 800 pages views, but my March 18, 2017 post entitled, Numerous Kent-like Calls Recorded on March 11 and 15, 2017 received a total of 744 views last year. Similarly, the post on Joseph Saucier’s October 2017 sighting and our follow-up visit to that location, Change of Pace Change of Place, posted in late November, received 804 page views, the second highest total for the year, (well behind the announcement of Frank’s passing).
According to a survey conducted in the aftermath of the Arkansas controversy, “[R]espondents were most confident in the sightings, less confident in the Luneau video and recordings of double-knocks and kent calls, and least confident in the FishCrow video.” The discrepancy was strongest for the “Definitely of IBWO” category, where 22 people listed sightings as conclusive, compared to 10 for the Luneau video, 9 for kent calls, 8 for double knocks, and 4 for the first Fishcrow video. (PDF) The Great Ivory-billed Woodpecker Debate: Perceptions of the Evidence. Available from: https://www.researchgate.net/publication/259337980_The_Great_Ivory-billed_Woodpecker_Debate_Perceptions_of_the_Evidence[accessed Jun 28 2018].
So sightings have an almost irresistible appeal; in some cases, there’s good reason to credit them, but it is very difficult to separate the wheat from the chaff, to determine what’s trustworthy and what isn’t. And there are many kinds of chaff – wishful thinking, self-delusion, ignorance, mistake, and deception to name the most obvious.
I’ve retrospectively rejected a couple of my possible sightings (and almost did so with the recent “Wooden Wings” incident), partly because I’m disposed to look for reasons to doubt myself and partly because I realized that I was in some way primed in a couple of those instances; for example, in one case, I’d been looking at specimens the day before. In the absence of a good look, I think it’s better to err on the side of self-skepticism.
When it comes to claims from others, it’s impossible to know with certainty what someone else saw, even when reports are accompanied by detailed sketches and field notes, as is the case with several of Frank’s sightings. I was with him for one, on April 3, 2015, when he made notes (available at the link) and a sketch (at my urging). I have no doubt that he was convinced he saw an ivorybill, as he was visibly shaken immediately afterwards and was very slow to regain his composure.
But I really like corroboration, and to the best of my recollection, Frank and I had two possible two-person sightings in all our time together – the first was in the old search area, the day after an auditory encounter and a week before a suggestive trail cam capture was obtained, effectively from the same spot. I consider this my strongest possible sighting.
The second was much weaker, a flyover with two birds seen in silhouette within 15-20 minutes of an ADK series. (Three of my possible sightings, two of which Frank also saw, have been associated with ADKs.) We did not think much of this possible at the time but could not explain it away entirely. I should add that Frank had several other two or more person sightings, but I was not present for those.
With regard to the local reports, I’m always mindful of the possibility that I’m being played, especially as an obvious northerner in rural Louisiana, but I don’t think that has ever happened. It’s still necessary to listen closely and ask the right questions. Pileated, Red-headed, and even Red-bellied Woodpeckers can be confusing for non-birders. I’m more likely to credit accounts from people who make it clear they know Pileateds and know the difference (like the landowner in the old search area) or from people who say they thought the ‘ones with the white backs are the males’ and the ‘ones with the black backs are the females’. I’ve heard this only a couple of times. But I like it best when we get ivorybill claims from different, unconnected people referencing the same location; this has happened in the vicinity of the current search area.
To conclude, members of our group have had multiple sightings of varying quality, in two different Louisiana locations since 2009. In addition, there have been multiple claims from locals in both areas.
One final note, relevant to the USFWS review: I am aware of a number of additional post-2009 claims from Louisiana (and a few from other states). In a couple of cases, Frank interviewed the people involved and found them to be credible. A cellphone video was obtained in one instance; the observers’ excitement over apparently seeing a pair of ivorybills is evident, but the quality of the video is extremely poor. In the other case, two people saw the bird and one provided a highly detailed description and sketch. There’s also Joseph Saucier’s report from last fall; our follow-up suggested that much of the habitat in this large expanse of forest was likely suitable, and Matt Courtman, who is an excellent birder, heard what he thought was a very good double knock on one of his follow-up visits.
I recently posted a couple of Frank’s 2009 sightings and accompanying photographs that hadn’t been made public previously. These are the only photographs associated with possible sightings that we have obtained. Full details are available at the link; rather than recapitulate them here, I’ll focus on trail cam photos, including several that have been discussed previously plus a few intriguing ones from the old search area that have not been posted previously.
These are the images I think are most strongly suggestive of Ivory-billed Woodpecker and for which I am unaware of a strong counterargument.
The first two have been discussed repeatedly at length in a number of other posts. Both are from the old search area; the first was taken in August 2009 and the second, which appears to show a female Ivory-billed Woodpecker, was taken in late November, a week after the sighting discussed in the previous section.
To reiterate a couple of points about the August 2009 image: in the original photograph, there appears to be some red in the crest (though it’s not positioned right for either PIWO or IBWO). Careful review and image enhancement made it clear to me that the red is an artifact and the crest is black. In addition, as shown in the enhanced detail, there appears to be a large, light-colored bill protruding from a cavity in the background. This apparent bill is absent from captures obtained on other days. It changes position in the two frames where it is visible, suggesting it is attached to something within the cavity. (Unfortunately, the other frames from that morning have long since been lost.)
The image of a bird in flight, from the new search area, is more problematic, as it is not demonstrably a woodpecker. The still above includes an inserted Imperial Woodpecker for comparison, with motion blur reduction applied to the bird captured by the trail cam. One prominent birder stated that it is a Blue Jay, but as discussed in the original post, the bird is behind the snag and appears to be as large as or larger than a Pileated Woodpecker captured on the trunk.
Although we’ve determined that one of the initially intriguing images from that deployment shows a Red-headed Woodpecker, a few others remain interesting.
There’s an additional image from the spring of 2010 (old search area) that has always intrigued me, though I never had a chance to examine the original. I think it shows a large woodpecker, with a black crest, high on a honey locust. If it were a Pileated, male or female, I’d expect some red to be visible in the crest, even under these conditions.
Finally, there are a couple of additional trail cam captures from the old search area that I have not posted previously. By now, the original sequences are lost, and I’ve long since forgotten any details or discussion we might have had when Frank sent me the images. While they are far from conclusive, I think they are interesting enough to post in this context. At minimum, they further illustrate the challenges associated with obtaining definitive trail cam imagery.
Note: If you listen to the recordings below with headphones (recommended) be aware that some have loud sounds, clarinet toots and ADKs, in the foreground. This applies to the clip from March 2013 that I recorded and to many of Matt and Phil’s recordings from March 2017.
Possible auditory encounters far outnumber possible sightings, and over the years we have made numerous recordings of putative kents and double knocks (more than once in combination, which should add to their evidentiary value). Some visitors have been rewarded by hearing something within a day or two of arriving, and this has been true in both search areas, although others have been less fortunate, and I heard nothing suggestive during the most recent field season (though Matt Courtman recorded three possible calls in April of this year).
I will not be including all the audio evidence we’ve obtained, just some of the material I think is most significant. Some of the putative kent calls that have been recorded over the years may be Blue Jays; it has been suggested that Matt’s calls from this spring are too low pitched for ivorybill and might be from a heron, though I think they come from the same source. Regardless, many of the calls are simply inconsistent with any known bird species, are fairly close to the Singer Tract recordings harmonically, and are perfectly consistent with written descriptions of Ivory-billed Woodpecker sounds.
One of the most dramatic encounters involving both apparent kents and double knocks was from the old search area. It seemed to have been triggered by banging from the tin roof of an old deer stand. Six people were present, and much of the incident was recorded. There were apparently two birds involved. More details are in this post, and here is Frank’s 58 minute recording:
Extracts from the encounter and other material recorded in person and on remote units in the old search area and environs, as well as sonograms, can be found here, via the Wayback Machine. Some of the Wayback Machine links are not functioning, and the material posted there includes a couple of double knocks; here are several of the recorded kent-like calls:
Note that the fundamental frequencies on many, but not all, of these calls are in the 900-925 hz range, higher than the Singer Tract recordings and possibly consistent with Blue Jay. But in the second clip above, the fundamentals of both the lower calls at the beginning and the higher calls at the end appear to be a little over 800 hz., and during the extended encounter mentioned above, the calls went on for a prolonged period without the source revealing itself as a Blue Jay, which would be typical if the animal were indeed a jay.
The same applies to calls I heard and recorded in the new search area on the morning and afternoon of March 2, 2013. The morning calls went on for ~20 minutes. I did not think they were Blue Jays in the field.
We have recorded apparent double knocks in apparent reaction to ADKs and to Barred Owl calls and sometimes in contexts where the trigger is unclear, as in this example from an October 2015 post written by Frank:
“Bob and I continued upstream for another half mile, located a nice spot with a good view, and I performed an ADK series, followed about ten minutes later by a series of electronic playbacks of Singer Tract ivorybill calls. Shortly thereafter, Bob heard a double rap drum, that was captured on my digital recorder. I personally don’t believe that the drum was a direct response to my ADKs as there was at least a fifteen minute interval after the last of the ADK/playback series.
The double rap is not “perfect” in that the “intra-knock interval” is about .05 seconds longer than the “ideal” – based on averages of the intervals of other Campephilus drums – but it sounds very good.”
The 15 minute interval between ADK/playback and apparent response is similar to the lag time that has been observed in other Campephilus woodpeckers responding to ADKs; it may be worth distinguishing between a slower ‘response’ and a more immediate ‘reaction’ in this context. (M. Lammertink, pers. comm.)
In my view, the audio recorded by Phil Vanbergen and Matt Courtman in March 2017 is compelling, perhaps the most compelling evidence we’ve obtained. On the morning of March 15, they recorded over 200 calls, along with a number of possible double knocks, over an approximately three hour period. The calls have lower fundamental frequencies than many of those in earlier recordings; these frequencies are considerably lower than any kent-like Blue Jay calls I’ve been able to locate online. Other suggestions have included, Red-breasted Nuthatch (too high) and Wild Turkey (no typical Turkey vocalizations were recorded that morning).
Overall, the calls appear to be inconsistent with any other known species of bird, mammal, or amphibian. Their association with Campephilus-like double knocks strengthens the argument for Ivory-billed Woodpecker as the source. As far as I know, the sheer number of recorded calls is unprecedented for a single incident in the post-Singer Tract era.
I was lucky enough to hear a couple of the calls on March 11, the day Phil first captured them, along with a couple more and some knocks at the same location on the following day. I’ve blogged about these recordings at length in multiple posts; I won’t repeat all that material here, but the discussions are worth reading. I will repost some of the original recordings and enhanced versions.
Here is the first recording Phil made, one clip with the calls isolated and one with our talk and reactions. It may be difficult to hear the calls without headphones.
Here are some brief extracts from Phil’s March 15 recordings:
Here are some from Matt’s:
In the interest of brevity, I encourage readers to visit this post for in depth analysis, various extracts, and amplified versions that highlight the calls and some of the knocks. As always, it helps to listen through headphones.
Indirect Evidence: Bark Scaling, Bark Chips, and Cavities
I’ve discussed my bark scaling hypothesis – that a certain type or types of scaling may be diagnostic for Ivory-billed Woodpecker – multiple times over the years. As explored in a couple of recent posts, we are in the process of testing it. I won’t recapitulate the hypothesis here except to say that I remain convinced that neither Pileated Woodpeckers nor squirrels are physically capable of removing hickory bark in the manner we’ve found in the new search area. There may be other diagnostic characteristics, but my main focus is now on the hickories, since the work on that species is the most extreme outlier. Below are some dramatic examples of bark scaling (plus one image of interesting feeding sign on a sweet gum sapling that had been stripped of bark) on hickories, oaks, and sweet gums from both search areas.
For Tanner, bark scaling was one of the strongest indicators of ivorybill presence, even though he accepted some reports from trusted sources in areas where he found no scaling. The absence of scaling (along with poor habitat “quality”) was one of his main reasons for dismissing reports during his 1930s survey and rejecting the ones from the Big Thicket in the 1960s. He also doubted reports from the Chipola and Apalachicola area in 1950 based on finding no cavities or scaling during a 4 day visit. He concluded his notes on the trip by stating:
Conclusion: No I-b now in Chipola R. and neighboring Apalach R. swamps. Many of Kelso’s reports are mistaken, – not deliberately false, but due to ignorance and wishful thinking. There appear to be contradictions in some of his stories. I could not get any clear statement of what Ivory-bills sound like from him. He said that the local name of I-b was “Saddleback”, – which appears good but in many ways odd. Also “Van Dyke”! There certainly is no fresh sign in any area we visited indicating that the birds are present. The only possibility is that of scaling on pine; this may be solved by watching Pileateds in the pine woods.
(F. Bryntesson, pers. comm.)
While I think it’s possible, indeed likely, that some of the work Tanner ascribed to ivorybills was done by Pileated Woodpeckers and squirrels, there’s no question that an abundance of bark scaling is relevant in assessing possible ivorybill presence in a given area.
Based on visits, some lasting a week or more, to suspected ivorybill haunts in South Carolina, Florida, and Louisiana and on information provided by other searchers and people who have spent years in southeastern forests, I feel safe in saying that the quantity and quality of bark scaling found in both search areas is unusual. We also found an abundance of scaling in the area where Mr. Saucier had his sighting last year, something that I think lends added credibility to his report.
In the past, many in the searcher community speculated that lateral groves or bill marks in the cambium or sapwood might be suggestive, but this view has fallen out of favor; much of what was thought to be “scaling” in these instances was in fact shallow excavation with associated bark removal. We found one example of superficial lateral marks in 2013 that continues to intrigue me, although the snag in question is a young sweet gum that could easily have been stripped by a squirrel or Pileated Woodpecker.
The edges of the scaled area may tell more of a story, especially in conjunction with any bark chips found on the ground. On the trees shown above, damage to the still-adhering bark suggests that lateral blows were integral to the scaling. This would be expected if the source were a Campephilus woodpecker.
An abundance of large, hard, thick bark chips (or chunks) around the base of a tree is also a likely indicator. Pileated Woodpeckers and squirrels seem to remove bark in smaller pieces and in strips. Additionally, when squirrels are involved and the bark has been recently removed, it’s likely that there will be a lot of smaller debris in the mix, since squirrels have to gnaw their way through the bark. Some of the chips we found in the old search area seem to have bill marks consistent with Ivory-billed Woodpecker.
The bills of specimens, at least, seem to fit perfectly into indentations in the chips, but Pileated Woodpecker bills seem to be too small. The larger chips shown below are suspected Ivory-billed Woodpecker from a variety of species – oak, hickory, sweet gum, sugarberry, and honey locust. The specimen shots are with a honey locust chip from the old search area. The first few images show squirrel and Pileated woodpecker leavings for comparison.
Cavities are vexing. I’ve become convinced that there’s no bright line for distinguishing Pileated from Ivory-billed Woodpecker, notwithstanding the dimensions Cornell gave for “large” PIWO (3.5″ x 3.7″) versus “small” IBWO (4.0″ x 5.0″). The small ivorybill sample was limited to nest holes, and I’ve certainly seen plenty of oddly shaped and large holes being used by Pileated Woodpeckers. Thus, while I keep my eyes open for cavities, I don’t think there’s a reliable way to determine which species is responsible for creating or using large, irregularly shaped cavities, although extensive bark scaling on the tree may be indicator.
It has been a challenge to find cavities of any kind in our current search area, probably due in part to the high canopy. We did find a cluster of interesting cavities in what I call the northern sector in the 2014-2015 season. This cluster was in the vicinity where we’ve found an abundance of scaling over the years and where Phil and Matt made the recordings last year. Below are some of the most interesting cavities we’ve found in the two search areas. Cavities were much easier to find when we followed up on the Saucier sighting, but I’ve omitted those from this document.
In conclusion, there is an abundance of evidence suggesting that Ivory-billed Woodpeckers persist in Louisiana. It is self-evident that none of this evidence rises to the level of proof required for establishing beyond all doubt that the species has survived, but I think the case for persistence is a compelling one, without regard to evidence obtained in other areas since 2005.
Stay tuned for a more theoretical discussion of evidence, proof, and professional approaches thereto.
Thanks to Wylie Barrow, Fredrik Bryntesson, Patricia Johnson, Tommy Michot, Steve Pagans, and Phil Vanbergen for their input. Some photos by Steve Pagans and Erik Hendrickson.
While I have not been keeping close track of numbers, I’m going to give some guesstimates on trail cam results. Our current settings (~12 hours daily at 20 second intervals) result in ~2000 captures per day with cards filling and beginning to overwrite at somewhere between 80-90 days. PlotWatcher’s proprietary software makes the process a lot easier than it was with the old Reconyx images, which had to be stepped through manually. This is the first time I’ve really immersed myself in reviewing imagery, and even with the ability to review the images in a video format, it’s a tedious process involving a lot of stops and starts.
I’d estimate that I’ve reviewed about 500,000 images over the past 8 weeks, and I’m struck by the relatively small number of hits, especially avian ones. Squirrels make up a significant percentage, probably more than half, the total captures, and I suspect that Northern Cardinals are second. Other common species show up infrequently. I don’t recall seeing any identifiable Blue Jays (although there may be one among the images below). Nor were any Wild Turkeys captured (including on a camera that was mis-aimed, with the target tree at the right edge of the frame and a large open area to the left as shown in some of the captures below).
Woodpecker captures have been extremely rare, except on the targeted hickory discussed post before last, that was already extensively scaled. Among the rest of the images I’ve reviewed thus far, I’ve seen three identifiable Pileated Woodpeckers – one on a target tree (below) and the other two on an adjacent tree that had one pre-existing PIWO foraging pit in the frame – and as best as I can recall, a couple of identifiable Red-bellied Woodpeckers and a Hairy (captures not saved/posted).
I suspect it would be fairly easy to obtain Pileated imagery in quantity by targeting trees with obvious PIWO foraging sign, but otherwise, it seems even this abundant species is hard to capture in a camera trap. This should help illustrate another reason I don’t think the so-called failure to obtain conclusive ivorybill imagery using trail cams is very meaningful.
Assuming the ivorybill persists, it is a very rare species with incompletely understood behavior, and no one alive today, myself included, knows exactly what makes a good target tree. The best anyone can do is make educated guesses and hope to get lucky, against extremely long odds.
Now some housekeeping: the next couple of posts will be about evidence. I’ve never assembled all of Project Coyote’s evidence in a single post and discussed it as I plan to in the next post, which I expect to take live sometime next week. Look for a more theoretical piece on evidence to follow that. Both of those posts will be password protected for review, though I will try and make them public as soon as possible. After that (probably in August), I’m planning a postscript to the habitat and historic range series.
I won’t be doing regular updates on the trail cam imagery unless there’s something significant to report or I have insights similar to those expressed here.
And now some imagery. It should be illustrative of some of the challenges. See what you can find, including in the featured image . . .
I suggest reading Part 1 for background and context, if you haven’t already.
The target of this deployment (5/3-6/3/2018) was the sweet gum stub discussed here. The tree was killed when its top was blown off in spring 2015. A patch of recent scaling was found this season. I suspect the initial scaling is woodpecker work, but squirrel is also possible. The extent is modest in terms of what I hypothesize is diagnostic for Ivory-billed Woodpecker:
A particular and distinctive looking type of extensive scaling (large contiguous areas with bark removed) with associated insect tunnels on bitternut and pignut hickory boles – live trees, snags, and stubs – may be diagnostic for ivorybill. For recent work, the presence of large bark chips at the base of such trees is a related potential diagnostic.
Insect tunnels are present on this stub. Species is/are unknown, and tunnels are small compared to those found in the hickories.
In contrast to the hickory discussed in the previous post, there were no woodpecker captures over the course of this deployment and squirrels were very active on the scaled area, appearing on May 4, 5, 8, 10, 12, 13, 15, 17, and 22. There were multiple visits on some days, and the total time spent on the scaled area was significant, upwards of an hour, with at least one visit lasting nearly 25 minutes. It was surprising that squirrel activity ended on the scaled area ended on May 22nd, and there was none over the next 11 days.
Over the course of this deployment, squirrels removed a modest quantity of bark, apparently in strips, from part of the scaled area. They did this inefficiently – with some difficulty and with the grain. The bark, already softer and weaker than hickory, has weakened in death and is at best moderately tight (relatively easy to peel off by hand). Captures from the first and last full days (note the Hooded Warbler on the branch to the left) of the deployment reveal how little bark was removed, all or almost all from the right side of the scaled area. (Click on the images to enlarge them.)
This suggests that squirrels are unlikely candidates for removing bark from hickory boles in quantity, leaving large chips behind, or initiating extensive scaling on hickories. In my view, it’s probably impossible for them to do so. The results for Pileated Woodpecker from the hickory deployment and squirrel from this one support my hypothesis that Ivory-billed Woodpeckers are the source of the initial hickory scaling. But more data are needed.
Before turning to the trail cam captures and accompanying images of the scaled surfaces, I’ll provide some background information on the impetus for this post and on squirrel behavior.
An email discussion of squirrels and bark scaling was ongoing prior to my starting to review the images from this deployment. Wylie Barrow suggested an alternative explanation: that squirrels might be the source of much of the scaling (including the work on hickories) that’s taking place in the search area. He pointed out that . . . “Squirrels have removed bark from 1/4 to 1/2 of the trunk and several large branches from large oaks in my yard… and they work with great speed. They often leave large bark chips on the ground beneath the trees. Trees are living and bark is tight and fairly thick.” (W. Barrow, pers. comm.)
At first, I took some umbrage at this suggestion, thinking that I had thoroughly examined and considered what squirrels might be doing on the hardwoods in our search area and what the upper limits of their capacities might be. While my basic views on this are unchanged, and the trail cam images tend to support those views, I’m grateful to Wylie for keeping me on my toes.
It’s certainly true that in the past I have failed to consider squirrels and the role they might play in bark scaling, and this has led me down some blind alleys, as was discussed in a series of posts in early 2016. I have also been too confident in those conclusions, even though I think this material supports them. Wylie’s suggestion led me to conduct additional online research on squirrels (and he provided additional references).
I had a number of off-the-cuff theoretical and observation-based objections to Wylie’s suggestion.
One evolutionary objection is reflected in a comment I made early in our exchange: “the predator in question would have to have evolved to take advantage of this very narrow window of opportunity when the insects are near the surface . . .” I thought and still think this points toward a woodpecker as the source, and toward a Campephilus woodpecker in particular, since this foraging strategy is characteristic of the genus.
The hickory scaling is associated with sapwood dwelling Cerambycid infestation, and signs of woodpecker activity (targeted digging around exit tunnels) are present in all cases. The homepage tree was very recently scaled when found, and woodpecker evidence was present. Wylie replied that squirrels are opportunistic and might be feeding on larvae; he went on to suggest that woodpeckers following the squirrels and doing targeted digs around the exit tunnels was a possibility.
In one paper on a tropical species of squirrel, it was observed that they prefer palm nuts infested with beetle larvae. The authors also note that squirrels have a strong preference for obtaining food in the most efficient manner, and that Eastern gray and fox squirrels will choose nuts lacking an endocarp (the hard inner shell) over those that are harder to open. When confronted with an endocarp, the tropical squirrels would attack it at its weakest and thinnest point, as do Eastern gray and fox squirrels :
Two of these pores have dead ends (with 1-mm depth), and the third is the germinal pore, which is deeper but is closed by a soft and easily penetrable tissue, located on the side opposite the fruit’s internal gibbosity. The internal gibbosity is a projection of the endocarp that inhibits the squirrel’s access to the endosperm when the fruit is opened from the side containing the dead-end pores. The squirrel must determine the position of the internal gibbosity to avoid it and thus save energy and time in obtaining the endosperm. These rodents are known to identify the side without the internal gibbosity even before beginning to open the fruit, with >90 percent success (Bordignon et al. 1996, Mendes & Candido-Jr 2014). However, how the squirrel identifies the side without the internal gibbosity remains unknown. As the gibbosity is always on the side opposite the germinal pore (Bordignon et al. 1996), this pore is an important access point that the squirrel can use to open the fruit efficiently. It is believed that the squirrel manipulates the fruit by pressing the three pores with its upper incisors, using the pore without a dead end for support so that the lower incisors can open the endocarp (Bordignon et al. 1996).
Efficiency is one of the main factors that determine the foraging strategy of Sciuridae. A laboratory study conducted with the squirrels S. carolinensis and S. niger found that individuals preferred various species of nuts with low energetic value that lacked an endocarp or shell over high energy nuts with an endocarp (Smith & Follmer 1972). These results suggest that there is a high cost in energy expenditure for processing seeds with endocarps for these species.
(Alves et al. “Queen palm fruit selection and foraging techniques of squirrels in the Atlantic Forest,” Biotropica 50(2): 274–281 2018). Efficiency is an important consideration in this context, especially with respect to hickories.
The reasons squirrels strip bark are poorly understood. Pine (or red) squirrels attack a number of tree species, “[d]uring winter, spring, and early summer, bark stripping and tree girdling for consumption of phloem and cambial tissues is common (Hosley, 1928; Linzey and Linzey, 1971; Pike, 1934). Pine squirrels also eat the bark of rust galls (Salt and Roth, 1980) as well as sap from sugar maple trees (Acer saccharum) in the northeast (Hamilton, 1939; Hatt, 1929; Heinrich, 1992; Kilham, 1958; Klugh, 1927; Layne, 1954) and yellow birch (Betula alleghaniensis) in the Great Smoky Mountains (Linzey and Linzey, 1971). Widespread, systematic sugar tapping by pine squirrels occurs in New England (Heinrich, 1992).” (Steele, M. A. 1998. “Pine squirrel (Tamiasciurus hudsonicus),” Mammalian Species 586:1–9).
Red squirrels have also been observed feeding on spruce bark beetles. (Pretzlaw, et al. “Red Squirrels (Tamiascurius hudsonicus) Feeding on Spruce Bark Beetles (Dendroctonus Ruffipennis): Energetic and Ecological Implications”, Journal of Mammalogy, 87(5):909–914, 2006). This was a novel observation at the time, and the behavior appears to have been a sudden and opportunistic response to a climate change-related bark beetle outbreak that lowered cone production. Spruce bark is soft, flaky, and fairly loosely adhering, and the bark beetles spend approximately a year, the entirety of their larval life cycle, in the phloem and hence are a readily available food source for a prolonged period. Moreover, “[f]oraging for larval spruce bark beetles by red squirrels is an obvious and stereotyped behavior; squirrels situate themselves on the trunk of the tree near ground level and peel off the bark to reveal and ingest larvae.”
There seems to be less agreement as to why Eastern gray and fox squirrels strip bark. It has been suggested that a calcium deficiency might be primary driver. C.P. Nichols et al., “A novel causal mechanism for grey squirrel bark stripping: The Calcium Hypothesis,” Forest Ecology and Management 367 (2016) 12–20. Bark stripping by Eastern gray and fox squirrels seems to be more prevalent in areas where the species have been introduced, “[b]ark-stripping behaviour, reported so often in Europe (Shuttleworth et al. 2015), is extremely rare in their native range (Kenward 1989).” (Koprowski et al. “Gray not grey: The ecology of Sciurus carolinensis in their native range in North America”, posted on Researchgate.com, 2016).
While “extremely rare” is an overstatement, it does appear that bark stripping occurs more frequently in areas where gray and fox squirrels have been introduced. It is a major problem in the U.K and Europe but mostly an annoyance in the United States. It seems reasonable to infer that it is more common in suburban and residential areas than in mature bottomland hardwood forests, though Wylie points out that the discrepancy in the reporting may be due to demographic factors and that squirrel behavior in bottomland hardwood forests has been poorly studied.
Gray and fox squirrel bark stripping seems to occur most frequently on branches, and I found no images in which insect infestation of the scaled areas was apparent. In addition, the examples of extensive squirrel scaling found online in no way resemble what we’re finding on hickories. Thus far, we have found only two references to squirrels stripping bark from trees in the genus Carya, one from pecans in Georgia and one from limbs in West Texas pecan orchards, where fox squirrels have been introduced. It’s not clear what parts of the trees were involved in Georgia and whether this report also came from an orchard, but regardless, pecan bark is flaky and not criss-crossed, making it easier to scale.
While neither Wylie nor I conducted an exhaustive literature review, we found no records of gray or fox squirrels scaling bark from any bitternut or pignut hickories (Carya cordiformis and Carya glabra), be it on limbs or boles, in several Google searches. Given the extensive range of these species – most of the Eastern United States and into Canada – and the association between squirrels and oak-hickory habitats, if squirrel scaling of hickories occurred with any regularity within the natural ranges, one would expect references to be abundant in both the popular and scientific literature.
As mentioned in the previous post and implied above, I suspect that the criss-cross pattern that characterizes pignut and bitternut hickory bark is one factor that deters squirrels from removing it and may prevent them from removing it in large pieces. This relates more generally to the question of efficiency. The characteristics of hickory bark make it extremely difficult for any creature to remove. In addition to the pattern of the grain, it is literally the hardest, strongest, thickest bark in the forest. On mature boles it can be 3/4″ thick (compared to around 1/16″ for a hickory endocarp). It is tight (though less so when sap is flowing), and it retains these characteristics long after death. Bitternut hickory bark does not flake, and pignut does so infrequently and superficially.
Thus, both species are exceedingly poor candidates for stripping by squirrels, especially when sweet gums and an array of other much easier targets are available. In contrast to the hickories, the target tree in this deployment was a sweet gum, three years dead, with thinner, considerably softer, loosening bark
As I see it, all of this militates against squirrels as the original source of the hickory scaling. While this is inferential and we have yet to document whatever initiates the scaling, the data obtained thus far support the inference. Only recently have we been able to deploy enough trail cameras for a meaningful and sustained effort. Nevertheless, we have had many hours of captures since 2009, in both search areas. To my knowledge, the only prior unambiguous capture of squirrel scaling is the one from 2015; it involved a downed, immature sweet gum with thin bark, which was easy for squirrels to scale. A second clip may show a squirrel removing a very modest quantity of thin bark from a sweet gum limb that was already being scaled by Pileated Woodpeckers (second video clip at end of post), and Wylie observed a squirrel scaling a sweet gum branch (on a roadside just outside the main search area) in December 2015.
I no longer think scaling on sweet gum limbs (so heavily emphasized in Tanner) is a strong indicator of ivorybill presence, at least not on its own, although what we’ve found in the search area seems to be unusual. Abundance, lack of correlation with low mast years, bark chips, absence of incisor marks, and indications of woodpecker activity, especially targeted digging, may all be suggestive. Sweet gums, which are very attractive to beavers, are likely one of the most desirable targets for squirrels as well, for reasons of flavor and efficiency.
But we have documented no squirrel scaling on hickories, live or dead, on limbs or on boles, partially scaled or with bark intact.
I think the results from this deployment shed considerable light on the issue of squirrels and bark scaling, especially what they do (or can do?) on a mature bole with thick bark. So let’s go to the videotape, as a New York sportscaster used to yell.
Squirrels on a Sweet Gum Bole
As with the previous post, our Plotwatcher Pro trail cam is programmed to capture one image every twenty seconds, and these time-lapse sequences have been converted into QuickTime movie format. If you want to get a clearer sense of how the squirrels are behaving, you can step through the films frame-by-frame. If you elect to watch just one of the clips, the one from May 8 that starts at Frame 1500 (the squirrel spent 24 minutes on the scaled surface) or the one from May 12 that starts at Frame 1574 might be your best bets. Discussion and close-ups of the scaled surface follows the bonus imagery.
While we had no woodpecker detections on the stub and bird captures were few, we did catch some hogs (piglets?) and a beaver. Also captured but not shown were a Northern Cardinal and an Eastern Phoebe.
Discussion and Details
As best I can tell, the only expansion of the scaled area involved a narrow strip at the upper right, probably no more than 12″ x 2″, and a little widening at the very top, although this was an area where the squirrels spent a considerable amount of time.
Let’s look at some details from that scaled area.
While there appears to have been some woodpecker excavation at the middle left of the larger scaled patch, there’s no readily apparent sign that woodpeckers have been after the insects that are feeding in the sapwood. Nor is there any strong indication that squirrels were feeding on insects over the course of this deployment, though it’s possible they took advantage of snails and beetles, like the ones in the photo, or slugs, which I also saw on the scaled patch.
The edges of the bark shown in the close-ups, especially the one at the top, show signs of having been gnawed, although this is subtle, and sometimes impractical as an identifier, since such close examination is not always possible in the field. I presume that the abundant squiggly abrasions to the surface of the underlying wood are incisor marks, something we have not observed with other scaling we’ve found.
With regard to what was left behind, the first three photos show what I found at the base of the snag when I discovered the scaling on May 1, 2018.
The large, though narrow, strip of bark was the biggest one I found at the base and is one of the main reasons I suspect that woodpeckers initiated the scaling with squirrels following, although I would not rule squirrel out completely. In any event, the bark was so soft and weak that it broke in my hand when I picked it up on June 11. The other thin strips are more consistent with what I’d expect for squirrel, and the tiny orange pieces of cambium are a giveaway.
The situation had changed little during this most recent trip. The picture with my boot shows the larger pieces of bark I found at the base, including the one shown above after it broke. They may be consistent with woodpecker (possibly including Red-bellied or Hairy), but I suspect that both squirrels and woodpeckers were involved in the bark removal.
Edited to add: For any extensive squirrel work on mature boles, especially hickories, I would expect to find many small pieces of bark on the ground, similar to those shown above, as in this dramatic example.
My main objective in targeting this stub was to observe it over time, more for what might happen as the decay advanced and whether it might become a target for ivorybills; it’s the type of “stump” that Pearson described as being favored by ivorybills after his visit to the Singer Tract in 1932, though Pearson’s “stump” (scroll down in the linked article) was much longer dead. The bark scaling, while interesting, was in the “could have been anything” category. Getting this data on squirrels was a pleasant surprise, one that I should have anticipated based on the small bits of cambium on the ground. My bias came into play, as I ascribed them to a smaller woodpecker. Between Wylie and the trail cam results, I’ve learned a lesson. In terms of the bigger picture, however, the results so far suggest that squirrels are not the source of the putative Ivory-billed Woodpecker scaling on hickories.
Summary/Bottom Line Up Front
5 of our 8 trail camera deployments (a 9th is planned) are targeting unscaled hickories, stubs and live trees that show signs of damage or decline. The main goal is to capture images of Ivory-billed Woodpeckers by identifying potential foraging trees and targeting them in advance of their being scaled (a long shot but the best strategy I can think of). A secondary purpose, especially with targets that already show some scaling, is to test my feeding sign hypothesis by documenting work by Pileated Woodpeckers and Eastern gray or fox squirrels (a much easier task). These are the only other local species that have the capacity to remove large quantities of tight bark from the boles of mature living and recently dead trees, though I suspect this capacity is limited. Results from two deployments, one on a still living but compromised and extensively scaled hickory (4/29-6/6/2018) and the other on a sweet gum stub (5/3-6/4/2018), suggest to me that neither Pileated Woodpeckers nor squirrels are the source of the initial, extensive hickory scaling.
Part 1 will address Pileated Woodpecker activity on the hickory, followed by a brief discussion of my visit to the search area from June 6-11. Part 2, which should be up within a week or so, will focus on squirrels, especially their activity on the sweet gum stub, which I think is analogous to the Pileated Woodpecker activity on the hickory. These are preliminary findings that may be contradicted by data obtained in future, but thus far they support the suggestion that Ivory-billed Woodpeckers are the source of the initial scaling.
Our PlotWatcher Pro trail cameras are dedicated time-lapse (as opposed to motion- activated) units. We set them to capture images at 20 second intervals, approximately between sunrise and sunset. The proprietary software makes it possible to create QuickTime movie versions of the time-lapse stills. The QuickTime versions are worth watching and are illustrative of behavior, but it’s important to remember that they are compilations of still images, not actual videos. Thus, it’s also worth stepping through them frame by frame. This will be an image heavy post but with a lot of analysis. I hope you’ll stay with it.
I am not planning to do posts on every review of every trail cam deployment but will post results that I think are a relevant or interesting to readers – PIWOs and squirrels spending time on scaled areas or removing bark, most or all woodpecker hits, mammals that are infrequently seen, identifiable birds, but not squirrels running up and down tree trunks.
Before turning to a discussion of the trail cam imagery, I’ll take this opportunity to restate and elaborate on my hypothesis. The imagery and discussion will be familiar to some readers, but I hope the new data will shed additional light, even for those who know the material.
Initially, I hypothesized that certain types of bark scaling might be diagnostic for ivorybill. Bear in mind, my focus has been on identifying a diagnostic, not covering the full range of what Ivory-billed Woodpeckers might do, so my criteria, especially this specific restatement thereof, may be overly narrow. Over time, and based on trail cam captures of Pileated Woodpeckers and a squirrel doing some scaling that seemed to match Tanner’s descriptions, I have refined and limited the hypothesis as follows:
A particular and distinctive looking type of extensive scaling (large contiguous areas with bark removed) with associated insect tunnels on bitternut and pignut hickory boles – live trees, snags, and stubs – may be diagnostic for ivorybill. For recent work, the presence of large bark chips at the base of such trees is a related potential diagnostic.
The tree on the home page (shown below) is one example. Numerous insect tunnels, some with signs of having been expanded by woodpeckers, must be visible. The appearance of the scaled areas is such that I can recognize older work even in the absence of chips. Because standing hickories (in drier areas at least) are slow to decay and the bark can remain tight for years, older examples persist, and I’ve found many of those over the years.
The hypothesis is founded on Tanner’s descriptions of scaling (although bitternut and pignut hickories were absent from the Singer Tract) and on the anatomical characteristics of Campephilus woodpeckers versus those of Dryocopus or Melanerpes, which appear to lack the physical capacity to do this type of work or do it extensively. The characteristics of hickory bark – chemical composition, strength, tightness, and thickness – are also central. I think the same limitation applies to squirrels, at least on hickories. This is not to exclude squirrels and PIWOs from coming along after the initial scaling and expanding it.
It recently struck me that grain may play a major role in limiting Pileated Woodpeckers and squirrels from scaling on hickories. Both species seem to follow the grain when stripping bark. Bitternut and pignut hickory bark differs from that of many bottomland hardwoods in having criss-crossed grain, making it considerably harder to remove, except in narrow strips like these, presumably removed from the target tree by a PIWO last year.
Based on the recent observations, PIWOs are more likely to dig through hickory bark to reach the sapwood than they are to scale it. I suspect it’s the case with the presumed 2015 PIWO “scaling” on hickory shown below, which is the only example of that type of work I’ve found. The differences may appear subtle in the photo, but they are more pronounced in situ; the work is patchy and discontinuous, and there are few or no exit tunnels. The chips at the base of this tree were small and included sapwood, indicating that this was actually shallow excavation with associated bark removal, something that is often and easily confused with true scaling.
Since 2013, we have found approximately 20 hickories that appear to have been recently or freshly scaled. Below are additional examples, plus some that were presumably several years old when photographed. In the case of the tree on the home page, the scaling was very fresh when found. I have not found any recent looking work of this type since March of 2015, though Phil found some last year that were probably scaled during 2016; one of these is the target tree in the sequences shown below. Steve Pagans has found several examples, but I’m not sure of any recent ones. Note the expansion of the exit tunnels, which makes it evident that woodpeckers have been active on the scaled surfaces.
A Cerambycid infesting the trees has been identified as Parandra or Hesperandra polita, a medium-sized, bole dwelling species with a 3-5 year life cycle.
H. polita remains, apparently of 2 adults, were found in one of the ivorybill stomachs examined by Cottam; it was collected in West Carroll Parish, August 19, 1903 and is referenced by Tanner. The adults of this species remain under the bark for some time after metamorphosis.
There may be additional subtle features, including chip characteristics and general appearance, that are relevant to other tree species and may be indicative if not diagnostic. A very nearly dead sweetgum, which had an intriguing cavity, from the old search area, is one example.
Trail Cam Captures – Hickory – April 29 -June 6, 2018
Over the course of this deployment, Pileated Woodpeckers were photographed on the target tree on 10 of 36 days, sometimes briefly and sometimes for periods of over 20 minutes. On some days in the latter part of the deployment, intervening foliage partially or fully blocked the lens, so it is possible there were additional visits. The camera is trained on the base of the scaled area, which extends to the broken top of the bole, and some of the sequences make it clear that pileateds are visiting the upper part of the scaled area as well. Phil Vanbergen found this tree last season; it is still living, although the sapwood is already somewhat punkier than what I’ve found on many longer dead hickories.
The first important point is that very little bark was removed over the course of this deployment, despite considerable time spent by Pileated Woodpeckers on the scaled area. The first two images are from the first and last days of the deployment for purposes of comparison. The new work is so minimal that it is only noticeable in the field upon close examination of the edges.
Pileated Woodpeckers were photographed on May 1, May 3, May 8, May 12, May 21, May 25, May 28, May 30, June 1, and June 4. A Hairy Woodpecker was captured on April 30 and on May 12. There were no squirrel captures on the scaled area. Individual frames and time-lapse films (when birds were present for more than a couple of captures) of the Pileated sequences follow. If you choose to watch/step through just one clip, I suggest the one from May 28, in which two birds are present, but viewing all of them will provide a better sense of what took place.
In addition to removing only a modest quantity of bark along the already scaled edge, despite being present on the scaled surface for over an hour altogether, it appears that the Pileateds are not actually stripping the bark but instead are excavating through it. This is also suggested by the quality of the bark chips on the ground. (The caption predates this imagery.)
The same appears to be the case for the presumed Pileated “scaling” on hickory in the preceding section. It’s unclear what the woodpeckers were seeking in terms of food, since there is no evidence of current or recent Cerambycid tunnels. In any event, the sequences give evidence of what Pileated Woodpeckers do on hickories, and just how inefficient they are at removing bark.
In the images we captured last year from a nearby deployment (on another scaled tree Phil found, approximately 100 yards away), the Pileated appeared to be scaling bark rather than digging through it, and this too was a very inefficient process. It involved removing long narrow strips, distinctly different from the chunks of bark shown above. In a sequence Frank and I captured on the homepage tree back in 2013, a Pileated appeared on that very recently scaled tree but removed no bark at all; a Hairy Woodpecker also appeared and removed a very small piece. (Scroll down to the bottom of that post for the relevant images.)
The trail cam captures validate my prediction that the source of this most recent work is Pileated Woodpecker.
Thus, we have documented multiple instances of Pileated Woodpeckers foraging on trees suspected to have been initially scaled by ivorybills. None of the imagery thus far shows pileateds removing bark rapidly, efficiently, or extensively. Such bark as they do remove is from areas that are already compromised, although I have found a single example of hickory bark presumably removed solely by a Pileated Woodpecker; it differs markedly from what I’ve hypothesized is Ivory-billed Woodpecker work. While it is difficult to prove a negative, the data gathered thus far suggests that Pileated Woodpeckers do not or cannot extensively scale tight bark from hickories. I suspect they lack the ability to do so.
Other Interesting Trail Cam Images
While these trail cams have limited usefulness, except at close range, all of our cameras are close to their main targets. They are positioned close enough for me to recognize lizards and even insects on the trunk but not identify species. Identification problems can exist for small birds too. I suspect the bird in the image below is a Brown Creeper, though I’m prepared to be corrected as it is so poorly resolved. If it is a Brown Creeper, it would be the latest record for the species in Louisiana.
And this series shows what appears to be a bobcat, at the lower right.
Some Brief Comments on the Trip
Nothing strongly suggestive of Ivory-billed Woodpecker was seen or heard – no ambient sounds or responses to ADKs. Tommy Michot joined me on Saturday, Sunday, and Monday morning. We deployed the 8th trail cam, aiming it at the bole of a sweet gum snag that has a scaled area; I suspect Pileated Woodpecker was the source, and squirrel is also possible, but the decay state is within the range Tanner associated with ivorybill, so this will be a long-term deployment.
Low water made it possible for us to explore some previously unvisited areas. Tommy did several stakeouts where Matt made the recordings this year and where I heard wingbeats and had a possible sighting. On Sunday evening, he observed a Pileated near the sycamore roost where I photographed one in April, and we watched it flying away from the roost on Monday morning. No wingbeats were audible in either encounter, as would be expected for Pileated Woodpecker as opposed to ivorybill.
Temperatures reached the 90s by noon every day, depressing avian activity and making fieldwork unpleasant. There were heavy rains on the afternoon of Sunday, June 10, so the 11th was particularly challenging in terms of heat, humidity, and suddenly high water levels. I had a close encounter with a cottonmouth that dropped from a tree limb within a foot of my head, landing in a slough that had been dry the day before.
One personal highlight was the abundance of chanterelles, especially after Sunday’s rain. I came home with several pounds, though transporting them was a challenge, and I couldn’t keep them clean. Despite a little grit, they’re delicious.
Here are some additional photos. There’s one new example of extensive bark scaling from the upland area shown in detail; it is interesting, but I would not consider it highly suggestive. There was also some recent scaling on a sweet gum that may be more suggestive. I was using a rented 4/3rds camera and a lens with an effective 200-800 mm reach. I had trouble adjusting to the electronic viewfinder, but it was good to get a closer look at one of the cavities found this season. I also found feathers from a Pileated Woodpecker that was presumably recently taken by a raptor; this was in an upland area within 50 yards of where I parked. This is the first time in all my years in the field the that I’ve found PIWO remains.
Stay tuned for Part 2. Like this one, it will initially be password protected so that colleagues can review it before publication.