Part 1 is here. Part 2 is here. I encourage you to read those posts first, as this one only adds a little to what’s been documented and discussed. Phil Vanbergen found an additional sequence this morning, one that shows the balance of the scaling that was done on the limb between December 22nd and January 26th.
In this sequence, Pileateds do most or all of the work that I had ascribed to squirrels. As in the other two sequences, the birds spent approximately fifteen minutes foraging, removing a couple of small patches from the lower part of the limb before working somewhat more extensively on the upper left. As in the other sequences, it appears that one bird did the vast majority of the work, but I haven’t found any frames that are well enough resolved to determine whether it was the female or the male. Per Phil, squirrels can be seen in additional sequences, “often poking around the scaled patches”.
Thanks again to all who sent condolences, and appreciations of Frank Wiley and our work. Your sympathy and support have comforted and encouraged me during this difficult time.
Part 1 is here. This post supplements the analysis at: Feeding Sign: Some Possible Ivorybill Diagnostics. I’ll be reiterating ideas that are familiar to longtime readers; I have posted many of the photographs before; but there’s some additional research and some new perspectives informed by the Pileated scaling sequences obtained in December and January.
I am now firmly convinced that the work we’ve found on a small number of hickories over the past several years cannot have been done by Pileated Woodpeckers. I have believed this to be the case for some time, but the recent sequences showing how Pileateds scale sweet gum bark provide strong, direct evidence in support of that conviction.
As noted in Part 1, sweet gum bark is in the mid-range for tightness among hardwood species. Hickory bark in general, and bitternut hickory bark in particular, is at the highest end of the range in terms of adhesion. Hickories belong to the genus Carya, which is divided into two types, “true” and “pecan” hickories. Bitternuts are in the pecan group, “which are not equal to true hickories in strength, hardness, and toughness.” This inequality is relative, and the differences are modest. In addition, the timber industry identifies bitternuts and a true hickory species, mockernuts, as “tight barked” hickories. True hickory bark adheres so tightly that its removal poses problems for the pulp lumber industry, and I suspect that for the purposes of the linked study, bitternuts are treated as true hickories. In any case, it is safe to say that hickories are the tightest barked hardwood species in our search area, and I have observed that hickory bark can remain tight for years after death, given the right conditions.
Now let’s examine the physical evidence we’ve found with regard to both sweet gums and hickories.
These are three of the largest chips found under the medium-sized limb of the downed sweet gum. There was one larger chip that broke on handling, as well as quite a few smaller ones. This is known Pileated Woodpecker work.
It is perhaps more accurate to describe these as strips. They’re approximately .25″ thick and 2″ across at the widest points.
Now let’s look at some presumed Pileated Woodpecker work from another sweet gum that appears to have been longer dead. This work is from somewhat larger limbs and a nearby hanging broken limb. I can see indications, patchiness and layered appearance, that would lead me to suspect Pileated, just based on the field impression. The chips are even more revealing, even though some of them are larger than what I would have expected.
Here’s an image of the chips found on the ground. There’s been a lot of scaling on this tree, and some older chips (that could be consistent with ivorybill) can be seen in the photograph. Note the variability in size.
Here are some of the fresh chips I collected, shown with my 13″ MacBook Air for scale.
Again, some of these chips are slightly larger than I would have hypothesized for Pileated Woodpecker, but the appearance, which suggests that a considerable amount of pecking was required before the bark was removed, would have led me to assume Pileated. I’m confident this is not squirrel work either, based on the exit tunnels and the way they’ve been pecked at (most readily visible at the far right). Note also that these chips were so brittle that the larger ones broke in transit. This work was done on larger limbs, and the bark is approximately .375″ thick.
By contrast, the hickory scaling is on boles, where bark is tighter and thicker; the surface area involved is typically much greater; and there is no sign of the layered appearance, which I presume to be a consequence of pecking rather than chiseling/prying. In those instances in which we’ve found fresh work, most or all of it appears to have been done within a very short timeframe. The example below, the homepage tree, was still alive, with the scaled areas wet with sap when found.
We found this tree in the spring of 2013 and monitored it regularly for over a year. There were no return visits by whatever did the scaling, and the only other woodpecker work involved the removal small patches of bark by a Hairy Woodpecker (captured on a trail cam). This particular tree had been partially uprooted and was in a lower, wetter area than many of the other hickories that have been worked on in this manner. By the spring of 2016, it had fallen and Pileated Woodpeckers were feeding on the rotting log.
I’ll repost the known PIWO scaling, done over approximately 30 minutes in two visits, five weeks apart, for comparison. Even if the same species of tree were involved I’d have suspected two different sources for the scaling.
As I see it, our Pileated sequences show that it would have required hours for a PIWO to have scaled so extensively on the hickory bole and suggest that they could not have done so as cleanly. The chips (>.375″ thick on a relatively young tree, not at all brittle, and no hint of pecking or removal in layers) and the remaining adhering bark should have a very different appearance if Pileateds were responsible, especially given the substantial differences between sweet gum and hickory bark adhesion and hardness. The work we’ve found on hickories involves both live and recently dead examples. Again, I’ll repost an image of the hickory chips from this tree for reference.
As discussed previously, the hickory scaling also has a distinctive appearance that strongly resembles presumed Ivory-billed Woodpecker scaling on one of the Singer Tract nest trees, a maple.
I think it may be possible to distinguish Pileated and Ivory-billed Woodpecker work on sweet gum branches, based on very close examination of the scaling and the bark chips (when possible). The effort to do so is complicated by the fact that both Pileated Woodpeckers and squirrels can and do strip bark in similar ways. Extensive, mostly contiguous, and clean appearing scaling on larger limbs may be suggestive for ivorybill, as in the example below and as Tanner suggests, but even if ivorybills are doing some of this work, identifying it requires making some fine distinctions.
By contrast, I think the work on hickory boles in our search area is diagnostic for ivorybill. Our focus going forward will be on trying to anticipate and document whatever is scaling bark from the hickories in this distinctive manner. Given the nature of hickory bark, I suspect I will have reached a dead end if it turns out I’m wrong about this.
One final note, identifying potential target trees is a very long shot. We found no scaled hickories of this type in 2015-2016. I have been looking for candidates on the last two trips and have found two wounded trees, both within 50 yards of hickories that have been scaled in recent years.
We’ll be targeting these and will be looking for two more when I return in March.
I’m still in mourning and adjusting to the loss of my friend. Thanks to all who have expressed appreciation for our work and a desire for it to continue. I’m sure Frank would have felt the same, and with that in mind, this will be the first of two or three installments discussing Pileated Woodpecker work on sweet gums that we’ve recently documented.
After my December trip, Phil Vanbergen and John Williams retrieved the trail cam we had deployed on December 21. They took the camera to Frank’s house, reviewed the card, and found that two Pileateds had visited the downed tree on the 22nd and had scaled some bark near the base of a medium to large limb. Phil, who has spent time with me in the field and who has paid close attention to my approach to analyzing feeding sign, immediately suspected Pileated for this work, based on the appearance of the scaling and the characteristics of the bark chips.
Rather than extract the images at that time, Frank and Phil opted to redeploy the camera. Although I had not yet seen the frames, many of my last communications with Frank, both on the phone and via email, touched on this subject. He was tickled by the fact that we’d anticipated and documented scaling activity on an untouched limb and was eager to get back out and see for himself. Sadly, that was not to be.
Phil and I retrieved the trail camera on January 28. I had visited the site on the 26th and had noted some additional scaling consistent with what I’d expect for Pileated Woodpecker, although with some bark chips on the larger side. As it happened, the second round of scaling had taken place approximately three hours earlier, five weeks to the day after the first.
In both instances, it appears that almost all the scaling was done by a female, although the image quality is too poor for me to be 100% certain. In both cases, the bird spent approximately 15 minutes on the trunk. It seems that squirrels (seen briefly at the beginning of the January series) are responsible for the modest quantity of scaling on the upper, less vertically oriented, part of the limb; this was my instinct at the time, and the idea is supported by the footage. The full time lapse sequences are at the bottom of the page. Phil extracted both sequences, and Steve Pagans created a slower version of the January 26th clip. The first four photos in the tiled mosaic series below were taken by Phil Vanbergen.
I’ll go into more detail in subsequent posts, but for now, I have a few observations.
- This work has a distinctive appearance, what I’ve called a layered look to the edges, that is consistent with what I’ve previously hypothesized for Pileated.
- While some of the bark chips are on the large side for what I have ascribed to Pileated, none are anywhere near as large as the larger ones that that we’ve ascribed to ivorybill. In addition, the chips found at this location and at another where I suspect the source is PIWO, seem to be less uniformly large in size and sometimes show signs of being taken off in layers, which matches what’s visible on the limbs.
- The tree in question was no more than six months dead, and the bark at the edges of the scaled area remained tight; however, dormant sweet gum bark is in the midrange of tightness relative to other hardwood species.
- This is a decay class that Tanner associated with ivorybills not PIWOs, but it’s clear that Pileateds can and do scale very recently dead sweet gum limbs, at least in mature bottomland forests.
- Tanner’s photographs provide little guidance in terms of differentiating between Pileated and Ivory-billed Woodpecker work on high branches. I suspect he thought of his monograph as more epitaph than guide to identifying feeding sign. Nevertheless, his descriptions offer some clues. “Scaling, the Ivory-bill works steadily, removing all the bark for quite an area; one may work at a spot for an hour or more.” And for Pileateds, “What scaling Pileateds were observed to do was mostly on loose bark and was never as extensive or as cleanly done as the work of the ivorybills.
To conclude this installment, we already suspected that Pileateds can and do scale freshly dead sweet gums before the bark has loosened; these images show them doing it in a way that is inefficient and neither ‘extensive’ nor ‘clean’. The total surface area scaled over approximately 30 minutes is modest compared to scaling we suspect to have been done by ivorybills. In addition, PIWO work has some characteristics that may be recognizable upon close examination of the affected limbs and bark chips. The fact that these characteristics can be seen on medium-sized sweet gum limbs, with their relatively thin and only moderately tight bark, suggests that it should be even more evident on larger limbs, boles, and other tighter barked species. More on this and on bark chips in subsequent posts.
1967 slides taken by Neal Wright of a putative Ivory-billed Woodpecker in Texas are viewable on Vireo (search Ivory-billed Woodpecker), but high resolution scans have not been widely circulated as far as I know. These images were not made public until after the the Arkansas “rediscovery”, more than three decades after they were obtained. Wright’s story is mentioned in Jackson (2004) “Reynard saw the photo and said that it was fuzzy but definitely of a Campephilus woodpecker.” It’s clear from the context that Jackson had not seen the images at the time of writing.
When I first encountered the Wright slides, I was skeptical, but after seeing some lesser-known Singer Tract photographs as well as other images of Campephilus woodpeckers in cavities, my opinion started to shift. After finding additional ivorybill photographs in the Cornell archives and in Tanner’s dissertation, I thought it would be worth posting some of those images along with one of Wright’s slides for the sake of comparison.
Of course, it’s up to readers to draw their own conclusions, but I think a few things are worthy of note. First, the Wright slides were taken long before the internet, at a time when the only readily available image of an ivorybill in a nest cavity was Tanner’s Plate 1, which is quite similar to Fig. 43b (below). The posture of Wright’s bird is much closer to the ones shown in the then virtually unknown and/or unpublished images, especially those from the 1938 nest. The placement of the cavity is also strikingly similar, just below a major fork. It seems highly unlikely that Wright would have been aware of obscure Singer Tract photographs.
While the image quality is too poor to be certain, there appears to be excavation similar to work found on some Singer Tract nest and roost trees to the right of the nest cavity in Wright’s slide. Again, this is a fine detail that would likely have been unknown to Wright and that would have been difficult to fabricate.
These are very poor quality images; the malar stripe seems a little too extensive, although this could easily be a function of angle and lighting. As with the Fielding Lewis photographs, which were taken several years later, I have to wonder why anyone intent on committing a hoax wouldn’t do a better job. And in the case of the Wright pictures, it would make more sense if the template for such a hoax would have been Plate 1 in Tanner, rather than photos that were unknown to all but a handful of people, most of them at a northeastern university.
Finally, I think the fact that the images were turned over to an ornithologist (George Reynard, scroll down for his obituary) but were kept confidential for so long also tends to support the idea that they’re authentic. Neal Wright may have had an agenda – a desire to protect the area where he took the picture – but the images were not used to serve that purpose.
Edited to add: This fascinating article on a recent, non-ivorybill related hoax suggests that it’s not uncommon for hoaxes to be paradoxically uneven in quality, and that hoaxers’ motives can be murky and bizarre. Nonetheless, I think that other factors point to authenticity for both the Wright and Lewis photos.
Another item I found in Tanner’s dissertation merits comparison with one of Project Coyote’s camera trap photos, since the tree species involved are the same. Plate 7 in Tanner shows ivorybill feeding sign on honey locusts, but the reproduction in the monograph is very dark. The figure from the dissertation is much brighter, making it clearer what Tanner was attempting to show. I think the similarity to the work on our target tree, where I had a sighting a week prior to the capture, is striking.
To enlarge the trail cam photo, click here.
To expand on some of the data included toward the end of the March trip report (which is worth reading in in conjunction with this post), I thought it would be informative to provide a season by season and sector by sector breakdown of the scaling I and others involved with Project Coyote have found since the spring of 2012. To do so, I’ve gone through my notes and photographs and have done my best to reconstruct the data collected. While not complete (I’m quite sure a good deal more scaling was found in Sector 3 during 2013-2014, for example), I think this breakdown is a fairly accurate reflection of what we’ve found over the years.
As discussed in previous posts, I think extensive scaling on hickory boles is the most compelling for Ivory-billed Woodpecker. Bark on this species is thick, dense, and usually remains very tight for a long time. Extensive scaling on sweet gum boles and oaks (upper boles and large branches) is second among work that I’ve found. Work on small boles, and higher and smaller branches is somewhat less compelling and is more significant for its abundance. Some of the high branch scaling and work on smaller boled sweet gums may well have been done by Pileated Woodpeckers (and possibly by Hairy Woodpeckers), but the abundance, the presence of large bark chips in many cases, the way it appears in clusters, and the fact that Pileateds scale infrequently suggest a different source for much of it.
I have excluded all work where squirrels are suspected but have counted one tree, a hickory found this year, on which the work could well have been that of a Hairy Woodpecker. Hairies do forage for Cerambycid beetles just under the bark, but they’re only capable of removing tight bark in small pieces; their work on hickories is perhaps more accurately described as excavation through the bark.
The trail cam images toward the end of this post are the best we have (out of many thousands of hours of coverage) showing how these species forage on suspected ivorybill feeding trees.
All trees were live or recently dead (twigs and sometimes leaves attached). All scaling was on live or recently dead wood.
Sweet Gum (Liquidambar styracifula)
Sector 1: 46
Sector 2: 8
Sector 3: 51
~15% had scaling on boles (a few of these were large trees). The majority of work was on crowns, including larger branches. Fallen trees were included when woodpecker involvement was evident and bark was tight.
Bitternut Hickory (Carya cordiformis)
Sector 1: 3
Sector 2: 4
Sector 3: 7
All trees were standing; scaling was on boles and was very extensive (the tree shown on the homepage is one example) with one exception from this year . Insect tunnels were visible in all examples. An additional hickory with a modest amount of high branch scaling was found in Sector 1 this year but was not counted for this analysis.
Oak (Quercus) spp.
Sector 1: 1
Sector 2: 4
Sector 3: 0
All oaks had scaling on large branches; one also had some on the bole. All oaks in Sector 2 were found in a single cluster.
We have some information on forest composition in Sector 3, and it appears that sweet gums make up approximately 19%, oaks upwards of 35%, and hickories somewhere under 10%. Sectors 1 and 2 may differ and be more varied in overall composition.
The overwhelming preference for sweet gums relative to their abundance stands out. The scaled oaks are a mix of species, one Nuttall’s, one willow, the others unidentified.
In Sector 3, I am treating the compact stretch from the location of Frank Wiley’s sighting last spring/downed sweet gum top where we had the camera trap to just south of our current deployment as a cluster. The estimate of 23 trees being found in this area is conservative. I have only found one instance of recent scaling north of the location of the downed limb/Frank’s 2015 sighting. The main cluster has been in the same vicinity this year and last, with additional work scattered around farther south. Two of the hickories are within 30 yards of each other, approximately half a mile from the cluster, and one was on the edge of the concentration.
It also may be significant to note that we found a cluster of old but intriguing cavities in the same vicinity as the Sector 3 concentration in 2013-2014. Most of these seem to have fallen. The difficulty we’re having finding active, suggestive cavities is vexing, and may be the most compelling reason to be skeptical about the presence of ivorybills in the area. At the same time, finding Pileated cavities is difficult, even in defended home ranges.
I’m treating Sector 1 as a single concentration; the vast majority of the work is on a natural levee where sweet gums are abundant. The entire area is considerably larger than the other clusters, but given the abundance and ease with which we’ve found sign there over the last five seasons, I think it constitutes one area of concentration.
In Sector 2, there was a small cluster in the area where I recorded putative kent calls in 2013, with work found in 2012 (spring and fall) and 2013. Because the area is small with open sight lines, I can be confident there has been no recent work there since late in 2013 (I last passed through it with Tom Foti back in March of this year.)
The sweet gum work Tom and I found on that day was perhaps half a mile north of this cluster, within 100 yards of the hickory on the homepage. The other hickories found in the 2013 and 2014 seasons were not far away, no more than 500 yards apart as the crow flies.
There’s obviously some bias here, since there’s a relationship between finding feeding sign in a given area and spending time there. Nevertheless, I have little doubt that the putative ivorybill work tends to be clustered. I also have little doubt about the strong preference for sweet gums, since I’m not looking at tree species when I look for scaling. The degree to which sweet gums are favored has only become clear over the last year or so.
Frank pointed out this data does not reflect most of the scaling that likely exists in relatively close proximity to the Sector 3 cluster but cannot be quantified because it is in an area we have intermittently visited due to inaccessibility. Only two or three examples are from this area, which has been visited a handful of times.
Frank and a visiting ornithologist spent this past weekend in our search area. I’m eager to read and will be posting Frank’s report before long. For now, suffice it to say they set up three trail cams, one on the snag where we captured the image discussed here and here and one on this downed sweet gum top found in April:
It most likely fell on April 19th. When I found it a couple of days later, it had fresh green leaves attached and no sign of insect infestation. Since then it has been partially scaled. This is an important data point, as we know the scaling took place within five and a half months of death, and Tanner documented the IBWO’s preference for freshly dead wood. We hope there will be a return visit soon.
They also placed a camera on an even more recently fallen water oak, something that started me thinking about possible patterns in the feeding sign we’re finding.
I’ve counted the examples of feeding sign from our current search area I’ve posted on the blog (which is by no means all the suggestive work we’ve found but is generally the most impressive), and the results for sweet gums are interesting, especially in light of Tanner’s observations suggesting an IBWO preference for sweet gums. Our results also suggest a preference for hickory. (Hickories were scarce in the Singer Tract, and apparently the species present in our area were not present there.) In both cases, the frequency with which we’re finding scaling seems to exceed the relative abundance of either type of tree, although we have not made formal counts. This sign was found between the spring of 2012 and the Spring of 2015, except for the downed top pictured above, which was scaled a little later.
The tally includes a couple of examples of work that falls short of what we consider to be diagnostic for IBWO. It also includes the small sweet gum snag that looks like it was attacked with a hatchet.
While there seemed to be a preference for sweet gums prior to the 2014-2015 season, the preference was considerably more pronounced this year when the abundance of fresh scaling on sweet gums in a relatively small area was astonishing. Here’s the multi-year breakdown:
Sweet gum: 25
Presumed sweet gum: 6 (One example possibly PIWO)
Oak species: 3
Willow oak: 2
Maple: 1 (Possibly PIWO)
Ivorybills fed on sweet gums in 42.6% of Tanner’s observations, scaling in 40 instances and digging in 3. Sweet gums made up 20.8% of the forest composition in Tanner’s study area. Next on Tanner’s list of preferred foraging trees were Nuttall’s oaks. By contrast, Pileateds “appeared to have no preference for any species of tree.” Tanner observed PIWOs feeding on sweet gums on fourteen occasions; nine involved digging and five involved scaling. He further noted, “What scaling Pileateds were observed to do was mostly on loose bark and was never as extensive or cleanly done as the work of the Ivory-bills.”
On a more speculative note, I think I’ve been able to identify one species of beetle that’s infesting the sweet gums, including the small one shown above. They’re an invasive, the granulate (formerly Asian) ambrosia beetle Xylosandrus crassiuculus (or another closely related invasive). Ambrosia beetles are tiny, but they are gregarious, with adult females creating chambers and tending broods of larvae in the sapwood. They can kill small trees but also infest larger ones. They have a relatively short life-cycle, and one source suggests they can produce 3 or 4 broods a season in the deep south. It’s worth repeating that I’ve seen signs of ambrosia beetle infestation elsewhere in Louisiana (near our old search area and in upland hardwood forest adjacent to our current one) but did not find work suggestive of ivorybills in either place.
We’ve found known IBWO prey species in our search area, on trees that we suspect were fed on by ivorybills. We also suspect that, contrary to Tanner, they may feed on darkling beetles. Could they also be feeding on an invasive species? We can see no reason to suspect otherwise and will continue our investigations with this in mind. I plan to return to Louisiana Thanksgiving week.
If you haven’t done so already, please read Trail Cam Photos Revisited for a more comprehensive discussion of the image that’s central to this post (including an explanation of our conclusion that the mystery bird is larger than a Pileated Woodpecker). At the time of writing, I didn’t envision doing a follow-up, but the nagging sense that the Rhein Imperial Woodpecker film might be even more relevant than I thought initially led me to go through the film again and pull an additional frame that showed the body profile, with neck extended, more fully and accurately. While I added an update to the original post that included a brightened composite for comparison, there’s a bit more to say.
We’re aware that many (perhaps most) in the scientific and birding communities will accept nothing less than a clear, high quality photograph (or series of photographs) or video. We’re also aware that many people will dismiss any post-processing whatsoever, even when intermediate steps are shown and the processing is relatively limited (in this case only involving the removal of motion blur). I must add, as should be evident from the images in this post, my skills with photographic post-processing tools are very limited. (Patricia Johnson, my wife, had to talk me through the rotation of the images in Photoshop.) Nevertheless, we think comparing the de-blurred mystery bird with frames from the Rhein film showing an Imperial Woodpecker in flight with similarly positioned wings makes a compelling case that our mystery bird is indeed an Ivory-billed Woodpecker.
Our choice of location for the game cam deployment was not random. As with this image (from our old search area), which was obtained a week after a sighting in the same location, the camera was deployed in an area where we’d had recent possible contacts – multiple double knocks (scroll to the end of the trip report) heard within a few hundred yards before and during the deployment, about a week before the image was captured. We also recorded an apparent double knock on the day we retrieved the cards. Thus, in both instances there was a close temporal association between a putative encounter and obtaining (at worst) a strongly suggestive trail cam capture. But I digress . . .
To return to the Imperial Woodpecker, these two screen captures are the most salient.
I was unable to find frames in the film that replicate the angle from which the mystery bird was shot. In the first of these two frames, the bird is flying downward and is angled slightly away from the camera, obscuring the bill and foreshortening the neck and tail. The second is a ventral view from behind, and the bird is angled downward. Our mystery bird is ascending and is seen in profile. Nonetheless, the similarities in both the extent of white on the wing and physical structure are striking. This becomes even more apparent when the Imperial frames are rotated and sized to match the mystery bird. Be sure to click on the images to see the full sized versions.
I concluded the previous post by observing, “We realize that this is far from conclusive but can think of few alternative interpretations, all of which are problematic.” Based on the comparison with known stills of the Imperial Woodpecker, I am now firmly convinced that the mystery bird is an Ivory-billed Woodpecker and do not think there’s a reasonable alternative explanation. Frank’s comment was, “People have been executed on far flimsier evidence.”