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.
My visits to Cornell’s Kroch Library, where the Rare and Manuscript Collections are housed, have been very productive. In addition to the last letter to Tanner pertaining to the Singer Tract ivorybills quoted at length here, I’ve come across several little known ivorybill images, some better quality reproductions of the plates in Tanner, and some additional hints about ivorybill foraging excavations that I’ll discuss in a future post. I suspect that all of the images below are actually stills from the 1935 film footage that has been lost save for a few minutes. To see it, go here and start at 14:00. To the best of my knowledge, these images have not previously been published as stills, and a couple of the frames may never have been publicly available.
The first image is similar to the one that appears on Page 82 0f The Race to Save the Lord God Bird. This is a sequence (that apparently has been lost) in which the birds are changing places on the nest. A third image that follows the first two appears on p. 120 of The Race . . . A colorized version, at once gorgeous and crude and sadly somewhat damaged, is also included here; it’s reproduced in black and white in Jackson (p. 27).
I think the bird in the remaining frames is the male. In the second frame, he may be engaging in the motion described by Tanner, “. . . jerking as though working food from the back of its mouth.” the next frame shows the him peering into the cavity. These two images are clips from the surviving footage. The final shot may have come from a lost piece of film, since a remaining clip, filmed from a similar angle doesn’t include it.
In addition to the images posted below, two figures in Tanner’s dissertation include unpublished photos from 1938 – one of a male at the nest cavity and the other of a juvenile peering out of it. Those images may also be included in a future post. All four pictures below were taken with my iPhone. I have a high resolution scan of the fourth on order, since it is one of the best representations of presumed ivorybill excavation available. Images are Courtesy of the Division of Rare and Manuscript Collections, Cornell University Library.
Careful examination of bark chips found in conjunction with extensive scaling is one of the key elements in our diagnostic gestalt, but “chips”, a term I’ve been using for years, is both inaccurate and too vague for what we believe is being left behind by Ivory-billed Woodpeckers and for differentiating it from the leavings of other animals. Tanner used “pieces” of bark, ranging “from the size of a “silver dollar to the size of “a man’s hand.” A caption from the National Geographic article on the 1935 Allen and Kellogg expedition that refers to “large chunks of bark”. The existing images of these pieces of bark suggest that chunks is the better term.
It’s important to reiterate that this discussion applies only to live and freshly dead hardwoods. Pines slough bark quickly after death. The process is slower in hardwoods, but as decay progresses, the bark loosens considerably, with the rate of loosening depending on species and environmental conditions. Once the bark has loosened sufficiently, PIWOs can and do scale bark extensively, sometimes leaving behind large chips. In the images that follow (from Allen and Kellogg and Tanner), the bark chips ascribed to ivorybills appear to come from considerably longer dead trees than some of the examples we’ve found, but the images are informative.
The small tree shown above, identified as a “dead gum” by the 1935 expedition, appears to be a hackberry or sugarberry not a gum, and a fairly long dead one; the pieces of bark at the base resemble ones we found beneath hackberries or sugarberries in our old search area, some of which were considerably larger (the one below is the largest).
This colorized slide reveals more about the bark at the base of these pines than the black and white print in Tanner (Plate 9).
There’s also this example, (Plate 10 in Tanner), which appears to be in a considerably more advanced state of decay, and presumably looser, than much of the work we find most interesting. I suspect most of the grubs were placed on the chip for illustrative purposes; the caption “Beetle larvae from beneath bark of Nuttall’s oak” is ambiguous as to where the larvae, which appear to be small Cerambycidae, were actually found.
What I think is most salient in Tanner’s description of bark chips is shape not size. In this regard, it seems important to come up with a more specific set of terms to replace the commonly used “chips”. I’d suggest using chunks and slabs for suspected ivorybill work (although smaller pieces of bark may also be present). Pileated bark removal can involve chips, strips, or flakes, the last when they’re doing the layered scaling discussed here and here. I suspect that squirrels remove hardwood bark primarily or exclusively in strips, and of course, their bark removal on cypresses leaves shredded bark hanging from the trees.
Let’s take a closer look at the differences among pieces of bark we have reason to believe were left by squirrels, those we have reason to believe were left behind by Pileated Woodpeckers, and those we suspect were left behind by Ivory-billed Woodpeckers.
I collected a number of bark chips from the tree we know to have been scaled by a squirrel, and while these were removed before our camera trap revealed the source, there’s strong reason to think they too were left behind by squirrels.
Note the uniformly elongated shape and the ragged appearance at the tops and bottoms of these strips of bark. This is not typical of bark that we infer or know to have been removed by woodpeckers, and it’s consistent with chewing, not scaling. The presumed squirrel strips I collected had the following dimensions:
The downed sweet gum from which they had been removed was a fairly young tree, and the bark is much thinner than on more mature ones. These strips were approximately 1/8″ thick. While this is a very small sample, we suspect (along with Houston from IBWO.net) that approximately 3″ is the upper limit for width when a squirrel is doing the bark removal.
Our research and observations suggest that Pileated Woodpeckers have two strategies for removing tight bark; one involves pecking around the edges until they can gradually pry off small pieces, and the other involves scaling away strips, sometimes in layers. Their physical structure precludes them from doing the extensive, clean scaling of tight bark that Tanner associated with ivorybills.
We suspect that this collection of chips, from a honey locust near a known Pileated nest, reflects the range of what the species is capable of doing on a tight-barked hardwood (and honey locust bark is relatively thin). The upper limit appears to be hand size, with many-quarter sized or smaller.
The following are measurements of some fairly typical suspected Pileated strips from a sweet gum:
The strips shown below, suspected Pileated Woodpecker leavings from a high branch, are on the large end of the spectrum for this category of work. The Peterson Guide is 9.5″ x 6.5″. I can’t rule squirrel out completely for these.
Flakes resemble strips, but they are removed in layers, so that reaching the sapwood is a gradual process. Pileated scaling frequently has this appearance, something that seems frequently to be the case with congeners, including the larger-billed Black Woodpecker (Dryocopus martius).
The chunks and slabs we suspect to be ivorybill work are significantly larger and thicker than strips, flakes and chips, although strips and chips may be present in the mix at the base of suspected feeding trees. Chunks are usually more irregular and varied in size and shape, and both chunks and slabs sometimes have what appear to be strike marks from a broad bill.
I kept one of the chunks scaled from the hickory tree on the homepage, a fairly typical example. It is 8.5″x3.5″ and .375″ thick. (It has undoubtedly lost some of its thickness after drying for over two years.)
The sweet gum chunk with the apparent bill mark Frank is holding is 7.5″x3″ and .25″ thick. On mature, thicker barked trees most or all suspected ivorybill chunks, chips, and slabs will have been removed cleanly, all the way down to the sapwood.
This particular bark “chunk” is intriguing on several levels. We have found that markings many describe as “bill marks” are really truncated galleries between the bark and sapwood. Marks made by woodpecker bills are distinctive, but somewhat subtle, and easily overlooked. This chunk actually has two interesting markings – markings that were left by the animal that removed the bark. The first is near the end of my left thumb – my right index finger is pointing toward it. It is about a quarter inch wide, a bit over a half inch long, and three sixteenths of an inch or so thick. The other is a “V” shaped “notch” at the end of the chunk, near the center of the photo. These places look as if they’ve been struck with a chisel – hard enough to rip the bark away from the sapwood/cambium. This suggests that, even though this bark was very tight, very few strikes were required to loosen and remove it. Granted that these marks are bill strikes, this suggests that the bird removing bark is indeed a powerful animal for its size. Back to Mark.
The two preceding examples are on the smaller side for suspected ivorybill work; in the first, the density, tightness, and grain of hickory bark seem to be a limiting factor on size. Some of the larger examples are shown in the Bark Chip Gallery (as are several of the images shown above). A couple of additional examples of larger slabs are below. In the first, the oak was approximately 8 months dead (leaves attached), and the bark was still tight. (The fractured slab was damaged in transit.)
Part 1 of this series is here, and the event that led to my writing it is discussed here. I now expect to write 2-3 additional posts on this topic and may create a new page that summarizes the whole series. I’ve hidden the Bark Scaling Gallery page to be reworked later or incorporated into the summary.
This post will reiterate, revise, and expand upon earlier ones dealing with bark scaling and woodpecker anatomy. The next one will focus on certain characteristics of the scaling we think is being done by Ivory-billed Woodpeckers, on finer details that characterize it (based in part on comparison with work done by congeners), and on how to differentiate it from bark removal done by squirrels. The following entry will deal with bark chips in more depth, and from a slightly different angle than previous posts on that subject.
I had originally intended to address the next post’s planned content in this one, but as I started writing, I realized the long but necessary introduction would bury the lede. It soon became clear that I’d have to divide the post in two with this one for background.
The first important point is that woodpecker taxonomy is in a state of dramatic change, so much so that the American Ornithological Union is being advised to place Downy and Hairy Woodpeckers in separate genera and that their current genus, Picoides, should be divided into four. Notwithstanding the taxonomic upheaval, there’s no question that Campephilus woodpeckers and Dryocopus woodpeckers are only distantly related, that their similarities are the product of convergent evolution, and that these similarities are far more superficial – involving size and coloration – than structural or behavioral. Formerly, some incorrect taxonomic assumptions led to the lumping of Campephilus and Dryocopus into the “tribe” Camphelini, an idea that’s discussed and dismissed in the first paper linked to above. This has been one factor in perpetuating some fairly common and persistent misconceptions – that the two species are closely related, that they occupy or occupied the same ecological niche and might be competitors, and that hybridization might be possible (something I hear surprisingly often).
The following differences are relevant to this discussion:
- Bill size and shape. These are dramatically divergent as any comparison shot of specimens makes clear. It’s also worth noting that the three North American Campephili are closely related to each other. DNA analysis suggests the three are distinct species and the Cuban ivorybill may be more closely related to the Imperial Woodpecker than the mainland US species. This study suggested that divergence among the three took place between .08 and 1.6 million years ago. The southern members of the genus are more remote cousins, having diverged approximately 3.9 million years ago. At one time, the southern species were considered a distinct genus, and they have smaller bills, both objectively and relative to body size. Magellanic Woodpeckers have the smallest bills relative to body size in the genus, and their foraging behavior is more Dryocopus-like than their congeners’.
- Neck length. The much longer neck of the ivorybill allows for a broader range of motion.
- Foot and leg structure. Campephilus woodpeckers have a unique variation on what have been called pamprodactylous feet. (Wikipedia and David Sibley both miss the vast difference between Campephilus foot structure and that of most other woodpeckers.) In this genus, the hallux (first) and fourth toe (the rear toes) are both on the outer edge of the foot; the toes can be rolled forward for climbing and backward for perching in a manner that looks more zygodactylous. (The preceding links to images of Sonny Boy, the juvenile ivorybill, and Kuhn are great illustrations.) The fourth toe is highly elongated, the longest toe on the foot, and the hallux, (in the ivorybill, the outermost toe) is relatively longer than in any climbing woodpecker species. The second and third (innermost toes) are angled inward. This is shown quite clearly in a number of the images from the Singer Tract, including Plate 13 in Tanner.
- Dryocopus woodpecker feet are closer to being truly zygodactylous – two in front, two behind, with limited mobility and the hallux as the inner rear toe, although the fourth toe can be rolled outward to some extent; this provides less stability when making lateral blows.
In addition, Campephilus woodpeckers typically climb and forage with their legs both farther apart and higher relative to their bodies than Dryocopus. This enables them to keep their lower bodies closer to the trunk and move their upper bodies more freely, providing more stability for making powerful, lateral blows.
4. Tail structure: the ivorybill’s tail feathers are long, thin, barb-like, and stiffer than the pileated’s. The tail serves as an anchor and also helps allow for a broader range of motion.
5. There other structural differences, including wing shape, but these are the main ones that point to how Ivory-billed Woodpeckers have evolved in a way that makes bark scaling their most efficient foraging modality, whereas Pileateds are far better suited to digging, using a perpendicular motion.
Much of the foregoing is based on Walter Bock’s analysis of woodpecker adaptations for climbing, which was also discussed in depth here. I’ve tried to explain Bock’s key points in straightforward and less technical terms. A longer quote from Bock appears at the end of this post.*
In addition to these structural differences, Pileated Woodpeckers (and to the best of my knowledge all their congeners) regurgitate when feeding young. Campephilus woodpeckers carry food to the nest and appear to be highly dependent on beetle larvae when caring for their nestlings. This means that Pileated Woodpeckers have to ability to take advantage of multiple food sources during nesting season, while Ivory-bills have a more limited range of options. While I don’t think this supports Tanner’s theory of old-growth dependence, it does point to a higher degree of specialization that would impact numbers, range, and suitability of habitat.
At the same time, the anatomical differences and degree of specialization convince me that certain types of feeding sign are beyond the physical capacity of a Pileated Woodpecker and are likely diagnostic for Ivory-billed Woodpecker.
There is a dearth of clear images showing Ivory-billed Woodpecker feeding sign. There are a handful of photographs, most of them very poor. The majority were taken in the Singer Tract and some showing work on pines were taken in Florida by Allen and Kellogg. Few of them depict the high branch work that Tanner described as being characteristic, and when they do, there’s virtually nothing that can be discerned from them. It is also not entirely clear that Tanner’s attribution of feeding sign to ivorybills was always based on direct observation, which makes us wonder whether some of the work might actually have been done by squirrels. Regardless, this makes it difficult to draw inferences from the existing body of imagery.
That said and with awareness of the perils in extrapolating, one lesser known image from the Singer Tract is worth comparing with the work on boles that’s been discussed in multiple posts.
“The Blind at Elm Rock”, Ivory-billed Woodpecker nest tree and detail showing scaling and excavation on trunk. Courtesy of the Division of Rare and Manuscript Collections, Cornell University Library
This is a view of the 1935 nest tree, which was a red maple. It’s taken at a different angle than the more familiar shots, so it shows some large areas of scaling on the bole that the others do not. While I can do no more than infer that this was done by ivorybills, it’s clearly old, and there’s an abundance of excavation in the underlying wood; nevertheless, the edges and contours of the scaling are strikingly similar to the work we’ve found on boles, especially the area at the lower right, just above the intervening foliage.
This is the jagged appearance I described in the previous post; the similarities are most evident in the picture below and on the home page.
Because there are so few informative images of ivorybill feeding sign, the best available option is to look at the work of other Campephilus woodpeckers. Even though they are not as closely related as the Cuban ivorybill or the imperial, their morphology and foraging behaviors are similar; even the work of the smaller-billed but oft-photographed magellanic can provide some clues. I’ll examine this and some probable identifying features of squirrel scaling in the next post, which will take a close look at scaled patches on trees.
*”. . . in most woodpeckers, as, for example, the pileated woodpecker, the legs are held more or less beneath the body,the joints are doubled up,and the tarsus is held away from the tree trunk. This position of the legs is disadvantageous for the bird, because the body is held away from the tree trunk and the muscles of the leg are working at a mechanical disadvantage; the analogy is to the mountain climber who is standing on a narrow ledge with hand holds only beneath his chest. In the ivory-billed woodpecker, the legs are directed away from the center of the body, and the tarsus is pressed against the tree trunk. This method allows the body to be held close to the tree, with the joints of the leg extended. Hence the leg muscles have a mechanical advantage, because they are at the beginning of their contraction cycle and are acting along the length of the segments of the leg. When the body is held close to the trunk, it not only decreases the outward component of gravity but allows the tail feathers to be applied to the supporting surface for a greater distance from their tips. If the bird is climbing on smaller limbs, the feet can encircle the limb and thus obtain better support. However, no matter what size the limb is, the disposition of the legs and the spreading of the toes of the ivory-billed woodpecker furnish direct and powerful resistance to both the lateral and backward motions of the woodpecker when it is at work and, with the tail, furnish a tripodal base of great strength against the pull of gravity.”
I made the mistake of trying to save on flights (actually paid with miles this trip), flying out of LaGuardia and a change of planes in Dallas. I left New York with a bad cold, and the first leg of the trip was miserable. Little did I know that the second leg would be worse.
At 4:45 pm, fifteen minutes before boarding time in Dallas, my flight to Louisiana was still listed as “on time”, although there had already been a gate change. There were five or six more over the next couple of hours, and American Airlines personnel at the various gates were either willfully dishonest or utterly clueless. The flight finally boarded at around 7 pm. We left the gate and sat on the runway for an extended period. At one point, the pilot announced that some planes were turning back, but that our crew could remain on the runaway until 1:30 am.
The pilot turned out to be wrong, as regulations now forbid planes from sitting on the tarmac for more than 3 hours. Somewhere around 9:30, we headed back to the gate. It took a while to find cooperative personnel, but I was able to rebook my flight for noon the next day. Sick as I was, I opted for a hotel rather than a night on a cot in the airport. I had to eat a room I had booked in Louisiana but used points to get this one. I got there a little before midnight and was in bed around 1 am.
I had planned to spend the 27th in the field, but that wasn’t happening. To the extent possible, I will avoid American Airlines and connecting flights in the future. Fortunately, my cold improved rapidly, and my rental car was a 4-wheel drive, which might have been a serendipitous result of the delay.
On the morning of the 28th, Brian Wiley and I went to an area that’s readily accessible from the road because we had plans to meet Tom Foti a little later in the morning. I spotted the downed sweetgum that we later found was being worked on, at least in part, by squirrels from the road. I found some recent scaling trees in this area, one where we’ve had possible sightings, concentrations of possible feeding sign, and auditory encounters in the past. While I can’t rule out squirrel work as a possibility, both of these trees were standing and somewhat longer dead than the downed trees that we now suspect are mostly being stripped of bark by squirrels; however, there was no way to find bark chips.
We met up with Tom at around 11 am, and we drove a few miles north to a location from which it’s easier to get into the mature bottomland areas. We spent the morning in this vicinity, where we’ve had a good deal of recent activity, but we did not see or hear anything of note.
I met Tom again the next morning, the 29th, and we covered a lot of ground, passing near a tree where we have a camera deployment (although we now suspect that much of the work was done by squirrels). We came upon another freshly stripped, downed sweet gum. Again, I now believe this to be squirrel work. (More on this in an upcoming post, but one indicator may be the presence of bark stripping on the underside of the limb at right.)
Tom headed back to Arkansas, and I headed back to Frank’s house. On the way, I passed the downed sweet gum that’s visible from the road and noted that there was fresh work on it. I went to examine it and noted that there was also some recently deposited scat.
I called Tom, and he turned around and met me. We collected the sample (which has a similar appearance to PIWO scat, although there was no urea, something that might point toward a mammal as the source). Despite the fact that we’ve documented squirrels stripping bark from this location, at over an inch long, this dropping was larger than and doesn’t resemble the images of squirrel scat found online. We are exploring the possibility of doing DNA testing on it . . . a very long shot indeed, but it may be worth a try.
Update, January 18: The consensus is that it’s not worth testing the scat.
Frank joined me on the 30th, along with Wylie Barrow and Tommy Michot, both great field people with a deep knowledge of bottomland forests and birds. They’re featured in Steinberg’s Stalking the Ghost Bird as leaders of “Team Elvis” south. It’s really amazing for laypeople like Frank and me to spend time with such experienced field biologists. Wylie probably knows more about the Singer Tract than anyone, and I’m looking forward to studying his materials on that subject. We didn’t see or hear anything of import, but I think it’s fair to say that Wylie and Tommy came away impressed with the habitat and thinking that ivorybill presence is at worst a possibility. Tommy took this photo of me crossing a log. He’s made of stronger stuff than I am and walked right across without hesitating.
I devoted the next day, 12/31, to staking out the downed sweet gum that proved to have been stripped of bark by squirrels. Nothing hit the tree for the entire day; it was cold, damp, and very uncomfortable, actually considerably more difficult than walking miles through the swamps. I did think I heard a single, pretty good double knock at around 3 pm, but I don’t trust that impression, given the fact that I was alone, tired, and hopeful.
On New Year’s Day, I left Frank to stake out the downed gum and went to retrieve a trail cam so we could monitor it remotely. While crossing an area of blowdown, I knocked myself down and nearly out, trying to break off the (not so) rotted limb of a downed tree.
I got the camera and met up with Frank. We then went to a location at the southern end of the search area that I had never visited before. Some of the habitat is very impressive, but there are many more signs of human activity (ATV tracks and empty beer cans in particular) than in some locations. We found some work on a downed sweet gum that we now think is almost certainly squirrel but did not see or hear anything else of interest.
On Saturday, the 2nd, I returned to the location I’d visited with Tom on the 28th; access is easy; it’s familiar; and it’s hard to get lost. I retrieved the card from the camera that’s trained on the downed sweet gum top I found in April. (The camera was unable to read the replacement card, so I ended up pulling it.) We’re unsure about whether the source of the scaling on this top is squirrel, as we’ve photographed them on it repeatedly over the past few months but have not documented them stripping bark. There was a little bit of fresh scaling on the tree (not enough to show up on the trail cam), and we suspect it to be Pileated Woodpecker not squirrel. Frank may replace this camera in the future.
I did not find any fresh feeding sign, but I did come across a sweet gum that had lost its top very recently, within days. I believe this to be a tree on which I photographed recent scaling last spring, and some of the fallen limbs had clearly been stripped before they fell. I found indications that a woodpecker or woodpeckers had worked on this limb at some point, as discussed in the previous post.
Perhaps the most significant event of the day occurred at around 11 am, when I heard an extended series of kent-like calls. At the time, I estimated the calling lasted for about 5 minutes, but I suspect it was closer to 15. These seemed to be coming from 200-300 years away, across a couple of challenging sloughs. There was really no way to try and follow them, especially alone. I did manage to record some of the calls on my DSLR (with no external mic). To my ears, they sounded pretty good, similar to the ones I recorded in March 2013, although they were all single notes, with no descending pairs. Unlike the 2013 calls (which were recorded on a better device at what seemed to be closer range), these came from a single, stationary source, not two moving ones. They were repeated considerably more frequently, and the pitch is slightly higher. Like the 2013 calls, they’re more clarinet than horn-like and don’t resemble the Singer Tract recordings in that regard.
In the attached audio clip (which may have lost some quality being transferred from .m4v to .m4a), the calls come at approximately, 4, 9, 17, 20, 25, 31, 39, 1:20, 1:27, 1:53, 2:07, and 2:17. I got the recorder running fairly late in the incident, and calls in the first minute of the clip are about as numerous as they were in the preceding minutes. They tapered off dramatically before ending at 2:17.
A variety of other birds are vocalizing throughout, including Blue Jays. I think the duration of the possible kents is shorter than the Blue Jay calls, but Blue Jay can’t be ruled out; I’m nowhere near as confident about these as I am about some others I’ve heard and/or recorded, including the 2o13 calls, but am posting them anyway. At around 3:41, Blue Jays start making an unusual call that we hear very frequently in this part of the search area. I do some playbacks of the Singer Tract recordings at around the same time, but there’s no evident response.
Per Frank, the dominant frequency of the calls is 1800 hz, with another bar at 2700. Since the calls are distant and the recording is poor, this might suggest a base frequency of around 900. The structure is more consistent with Blue Jay than known ivorybill. On the other hand, the duration is between Blue Jay and the ivorybills on the Singer Tract recordings. Allowing for attenuation by distance, this makes Blue Jay less likely.
Later that morning I did some additional playback and got apparent responses from Blue Jays and a White-breasted Nuthatch. This is the first time I can recall hearing a WBNU vocalization immediately after an IBWO playback.
On the evening of the 2nd, Frank and I went through the card and found the two sequences of a squirrel removing bark. Seeing the images was a bit of a blow, though not a total surprise; Wylie Barrow had raised this possibility a day or two before. He was the first person ever to make this suggestion; removing bark from hardwoods seems to be a fairly unusual and poorly understood behavior in squirrels; most of the information online suggests that it’s done on standing live trees when food is scarce, not on fallen ones when other food is abundant.
I shared the news with several biologists, and a couple of them pointed out that not all of the work we’ve found fits the squirrel paradigm. In fact, I think most of what we’ve ascribed to ivorybills is inconsistent with squirrel and am in the process of trying to identify some diagnostics. Unfortunately, since we know squirrels are doing at least some of the work on downed trees, an avenue that seemed very promising for camera trap deployment now seems far less so.
I returned home on the 3rd, and to my relief, the trip back was uneventful save for the usual post-holiday chaos at LaGuardia.
I plan to do a series of follow-up posts exploring scaling in more depth within the next week or two. I also hope to be able to provide some stills from the sequences we obtained.
Part 1 is here.
Thursday the 26th was Thanksgiving, and Frank spent the morning cooking. I ventured out alone; I get less comfortable going solo every year. Because I’m not very good with a GPS, I tend to prefer visiting areas I know well or restricting myself to places where I can rely on my sense of direction, compass, and iPhone map to get out safely.
For these reasons, I returned to the area where we had concentrations of scaling in 2012 and 2013, and where I recorded calls and had a possible sighting in 2013. There has been a significant increase in human and porcine activity in this area; both people and hogs are having an impact on the hydrology, and places I know well have changed a lot in less than three years.
I did not see or hear anything of interest – no sign, no calls, no knocks, but this is where access to the bottom is easy. The damage is being done on the periphery, and the core is much harder to reach. (Much of the activity in 2012 and 2013 was remarkably close to the edge.) Most of our attention has been focused elsewhere since 2014, so there’s no telling what might be going on in less accessible parts of this sector.
November 27th was something of a banner day but also a very difficult one. Frank, Brian, and I got to an area that hadn’t been visited before, although we did cross a track that Frank and Bob Ford made back in October. Access to the bottom involves hiking approximately 2 miles, .5 of which is on an old logging road. The rest is cross country and is not easy going, since there are dense pine plantations to traverse. Beyond the pines, there are several sloughs to cross or circumvent, but once you get there, it’s an incredibly beautiful area.
As Mark says, the area is quite beautiful once one has made it into the core. The difficulty in reaching the “core” cannot be overstated. The portion of the hike on the old logging road (actually more of an overgrown trail) is not too difficult, but once committed to crossing terrain, it becomes an entirely different story. We have often remarked on this, but I believe a little more explanation of exactly why the going is so tough will help the reader to better grasp the challenges.
Once the trail is left behind, one has to decide whether to blaze a straight line, or allow the terrain to dictate the direction of travel and work in a general direction. We generally just plow through thicker, younger pines in a straight line. The buffer habitat, which runs to middle aged pine with some oak and hickory scattered about is not too bad for either choice – at first glance. Once into these areas, one finds a lot of blown down timber in various stages of decay, from very recent to several years old. Even on level ground, these blowdowns require going off course, or stepping over. Then there is the occasional blackberry or saw briar patch to contend with.
As one continues to approach the core, the sloughs that Mark mentioned in passing begin to impose obstacles. Many times, to maintain a straight course, we find ourselves crossing the same slough several times. The sloughs are of two types, each presenting a different set of challenges. The first are the tributary sloughs. These are often dry, but are incised into the surrounding terrain, requiring one to find a way into and out of the streambed. The depth of the incision varies from a couple of feet to as much as ten to twelve feet depending on the carrying capacity of the slough, and its proximity to the main stream channel. The second type are the larger cutoff, stillwater sloughs. Once the rains begin in October, these hold water all the time. While only incised a foot or two into the terrain, they can be a couple of feet deep, often just enough to overtop one’s boots. This requires leaving the course line and hunting a place that’s shallow enough to cross – or finding a log to cross on. Waders, except during the wettest, coldest times, are not really practical as they get very hot and uncomfortable on even slightly warm days. Another challenge is the uniformity of the various types of habitat. Without a compass or GPS (I use a very high end Lowrance unit and carry a high quality compass for backup) one can be seduced by the easier walking and just make big circles, not really covering much ground. I’ve lived near, and turkey and deer hunted in this area for much of my life, and a few lucky souls get to spend a night or two in the woods every year.
On this particular day, Friday the 27th, the understory in the portion of the core area we visited was quite thick, unusual in this bottom, where the core areas tend toward an open hardwood gallery forest. The area is just a bit higher in elevation than most of the rest of the core – perfect for native bamboo canebrake. The cane affords a bit of protection for the blackberry briars and other “catchy” vegetation, making traversing even the heart of the bottom in this particular area a difficult proposition. On our way out, we encountered one of the “stillwater” sloughs that I mentioned earlier. Brian and Mark got water in their boots crossing it. I found a downed loblolly that made a pretty good bridge, but the bark was long gone, and the log was unbelievably slippery. I “scooted” across rather than risk a dunking, and strained my wrist in the process. Maybe I should have opted for the wet feet…
At the farthest point from the road, we found a recently downed sweet gum top that had been fairly heavily scaled (more heavily than the similar tree we found on the 24th).
The hanging, shredded bits of cambium on some of the scaled areas appear to be what Edith Kuhn Whitehead said her father considered diagnostic ivorybill sign. This led me to revisit Tanner and look at Plate 8; the images of feeding sign in Tanner are very poorly reproduced, and the originals are not much better. There is a higher quality scan of Plate 8 on the US Fish and Wildlife Service’s website, and after another look, we’re struck by the similarities between that image and a couple of the above details. While Tanner is often opaque about his reasons for selecting images of feeding sign, we suspect Plate 8 was included to illustrate what Mrs. Whitehead described.
We spent over an hour in this location and heard multiple possible kent calls and double knocks. We captured one of the double knocks on Frank’s recorder, but it’s too faint to be analyzable. One of the calls that I heard (but Frank did not) was perhaps the most Singer Tract-like ever to my ears, so much so that I had to ask Frank whether he had done a playback.
On the way out, I spotted some more extensive high branch scaling, apparently on a sweet gum within 25 yards of the downed tree.
Unfortunately, while the location is fairly close to the concentration described on the blog, it’s only reachable as the bird flies. We’d love to put a camera on it, but that’s not possible at this time. And all four cams are deployed in promising locations. We don’t have the time or personnel to handle more than we’ve got.
On Saturday the 28th, we retrieved the card from the camera that’s trained on the downed sweet gum top. It functioned perfectly but produced no hits. We did get some apparent double knocks after a series of ADKs; one was captured on the recorder but again was too faint to be analyzable.
We’d like to address a Facebook comment from a British ornithologist and extinction believer who characterized our inability to obtain something conclusive thus far as “negative evidence”. The fact of the matter is that the negative evidence we’ve obtained relates to Pileated Woodpeckers, not ivorybills.
Pileateds are abundant throughout the area, in the uplands as well as the bottoms. I constantly scan the woods for suggestive scaling. To repeat something I’ve said in a couple of earlier posts, we have seen an abundance the type of work we think is characteristic of ivorybills in our two Louisiana search areas. I have looked at Pileated sign throughout much of that species’ range and have examined countless images of Pileated Woodpecker scaling online. I have not found any examples that match what we take to be ivorybill work. Nor have I ever found any in our search area’s mixed pine-hardwood uplands. In the bottomlands, we’ve found this work scattered throughout the mature forest. We’ve also found clusters of it in several locations. In a couple of places, like the area I visited on Thursday, there have been concentrations of scaling in one or two years and not in others.
This week we got a series of images of a PIWO on both forks of the downed sweet gum top (not retained), where it spent several minutes. It did no scaling. Over the years, we have obtained a few sequences showing the same behavior, including this one. In a single instance, we captured a Pileated scaling a quarter-sized piece of bark, with some difficulty, from our target tree, a freshly dead oak. It did nothing more, and approximately six months elapsed between incidents of major scaling. (The second round happened after we’d removed the trail cam.)
There’s no way to prove a negative, but the evidence we’ve obtained points to something other than Pileated Woodpeckers as the source for the following reasons:
- The scaling is unlike work done by Pileateds elsewhere.
- We have documented Pileateds on heavily scaled trees but have not documented them removing anything but a single small piece of bark.
- The distribution of the scaling in our search area points to something other than Pileated Woodpeckers as the source, since Pileateds are abundant throughout, and the scaling is found only in mature bottomland hardwood areas, not in mixed and hardwood dominant uplands.
- The fact that we’ve found concentrations of scaling in certain areas in one year and not in others suggests that whatever is doing the bulk of it has a home range that’s considerably larger than that of the Pileated Woodpecker.
- Anatomically, bark scaling is an inefficient foraging strategy for Pileated Woodpeckers. It seems unlikely that Pileated Woodpeckers would do so much foraging in such an inefficient manner when other food sources, including insects in rotten wood and (at this time of year) mast, are abundant.
We hope the current camera deployments will solve this mystery of what’s doing this type of work . . . within the next few weeks.
I’ll be posting Frank Wiley’s report on his recent visit to the Project Coyote Search Area in two parts. Below is his account of his first day in the field.
I was contacted last month by Bob Ford, a biologist with the USFWS in Tennessee, about a possible visit to the Project Coyote study area sometime in early October. After some back and forth, we agreed that the weekend of the 9th would be best for both of us. Bob has visited the area in an unofficial capacity on a couple of previous occasions; he is a skilled birder, with a Master’s Degree in Wildlife Science. His focus has always been on birds and bird-habitat relations, especially in bottomland hardwood environments. All that aside, Bob is a great guy to spend time with, and an all-around skilled woodsman. He arrived on the evening of the 8th, having spent the earlier part of the week fishing in South Louisiana with some of his colleagues with the USFWS.
October 9, 2015:
We arrived at the study area at dawn, shouldered our packs and entered the forest. This particular spot is in the northern sector, and provides the easiest access to the area that we informally call Jurassic Park from a road that passes through the surrounding uplands – thus cutting out over a mile of fairly difficult foot travel at the beginning and end of the day. We were barely out of sight of the truck when I heard a rapid ticking sound in the leaf litter near my feet. I thumped the ground with my walking stick and was rewarded when a Copperhead about 18” long moved due to the vibration. Only a moment before, it had been completely invisible, camouflaged by the surrounding leaf litter. We stopped for a few moments, took a few photos and left the little guy to go about his business.
We hiked a fairly difficult three quarters of a mile through the bottom, crossing several deeply incised sloughs and secondary creek channels. The area was extremely dry; there’s not been a significant rain event since early July, when a series of severe thunderstorms passed through. Stealth was impossible, the dry leaf litter making it sound like we were walking on Corn Flakes. We made it to the main channel, and walked beside it until I found the top of a sweet gum tree that had blown down during Mark Michaels’ last visit. (It had green leaves and no sign of insect infestation when it fell in April.) We had speculated that there was at least a decent chance that ambrosia beetles would infest the two main forks of this top over the summer, and hopefully attract large woodpeckers. The smaller of the two forks did not disappoint. Not only had it been infested with beetles and larvae, the bark had been stripped from 60% or more of the branch. The scaling, in all respects fit the very narrow set of parameters that Mark and I have come to believe can be considered diagnostic as the work of an Ivory-billed Woodpecker – that is, extensive scaling on a freshly dead/dying tree with very tight bark, large (silver dollar or larger sized) bark chips that have clearly been removed with one or more powerful strikes, and little or no damage to the underlying sapwood.
When Mark first spotted this top on April 21, we both felt it was important to get a camera to this location to watch for woodpeckers. With this in mind, I had brought one of our new “Plotwatcher Pro” HD time lapse video cameras with me. I found a nearby tree that gives the camera a nearly perfect angle for recording any succeeding visits to this downed top by a woodpecker – both the stripped part, and the part that is almost untouched. We have high hopes for this camera in this location. It will take a photo every 5 seconds from 6 AM to 7 PM every day for three months or more according to the manufacturer.
While we were stopped, we took the opportunity to perform an ADK series and run a couple of playback sequences. During the quiet period, we neither heard nor saw anything suggestive of IBWO, even though there was a lot of activity from other woodpecker species.
As the main stream through the bottom is at a lower level than I have ever seen it, we took full advantage of the opportunity, and crossed at a location where the banks were eroded in such a way as to allow us to get in and out. Remember that the stream bed is incised approximately 15′ into the surrounding ground, so one has to be careful in choosing a crossing point, even with the stream completely dry in places. We did an “M” shaped transect that involved about 3 miles of difficult to negotiate terrain. The dry sloughs and incised cutoff channels are much more common in this area, making traversing the terrain much more difficult. We stopped at lunchtime and at two o’clock performed ADK series and playbacks but heard nothing suggestive of ivorybill activity.
At one point, I was walking near a large tree, paying more attention to the canopy than where I was putting my feet, when I happened to glance down. I quickly hopped to the side, because my left foot was about 3″ from the head of an enormous Canebrake Rattlesnake (Crotalus horridus atricaudatus). Bob backpedaled about 5 quick steps and asked, “Where’s it at?” Like me, he was very impressed with the size and apparent health of this beautiful and potentially deadly predator. Bob later said that he reacted the way he did because, “If it was big enough to startle you, I didn’t want to get too close…” We took a number of photos while the big guy (we estimated his length at nearly 5′) lay placidly with his head on a root buttress, clearly waiting on a convenient squirrel to pass within striking distance. He seemed totally unconcerned with our presence as we circled him (I got quite close several times) making photos. Finally, I just couldn’t resist and asked Bob if he wanted to hear him buzz. I gently poked him with my walking stick a few times. After the third poke, he rattled a bit, and coiled into the “OK, I’m pissed, now leave me alone” position. For those who’ve been dying to know, the answer is, “Five, and a button…”
We exchanged a happy high–five at having encountered this big guy and continued going about our business, leaving him to go about his. Truly an awesome and exciting encounter.
As the day wound down, we worked our way back to the stream, having explored about two and a half to three miles of ground that no one associated with Project Coyote had explored previously. The forest is of outstanding quality with many superdominant trees, mostly sweet gum and Nuttall’s Oak indicating a mature, healthy, and beautiful swamp forest. We crossed, and made our way back to the truck, feeling good about a productive and enjoyable day in the field.
As I mentioned earlier, Bob had spent the first part of the week with some of his USFWS colleagues fishing in south Louisiana. They were successful in bringing home some Redfish and Speckled Trout, both game fish that are exceptionally tasty. When we got in, we cleaned up, and I fried up a good mess of both kinds, along with steak fries and hush puppies. Bob liked my fry mix so much that he brought two ziploc baggies of it home with him for future use. I can make more. Got to teach them folks from up north how to cook!
Mark here pointing out that Bob’s from Tennessee, hardly up north from where I sit. Stay tuned for Part 2.
Day 2 – October 10, 2015
We have only visited the southeastern quadrant of our “northern sector” four times. This is mainly due to the amount of time it takes to cross about a mile and-a-half of the uplands surrounding the bottom. Bob and I decided we would try a longer, but possibly quicker and easier, approach by following a fire lane that is maintained a couple of times a year. It was a pleasant, if boring, hike of about a mile and three quarters, a little further, but much easier going to get to the edge of the bottom.
The forest on this side of the stream is of a somewhat different composition than that on the other side. As well as the sweetgums, loblolly pine, and various Quercus sp. an appreciable percentage of the trees are mature 3′ DBH or more beeches.
We made our way to the main channel with relative ease – this quadrant of the forest seems not to have as many deeply incised sloughs and secondary channels, so the temptation to just keep moving slowly is irresistible. After reaching the main stream, we began to do half-circle transects, looking for anything interesting. We finally took a break about mid-morning, and I performed an ADK series and shortly thereafter a series of playbacks. We then sat quietly for about thirty minutes.
We were separated by about 15 yards, and Bob was sitting at the bottom of a large tree facing away from me. Before we continued on our way, we compared notes, and we had both heard two double knocks, and possibly one kent call. Kent calls, what are and what aren’t, have been debated ad nauseum for years. Suffice it to say that this one, though further away and not as loud, stood out from the Jays that were making a ruckus all around us. All we could say for sure is this one was “different” in a way that’s hard to describe.
We continued on, finding our way back to the bank of the main channel every so often. The stream is dryer than I’ve ever seen it.
At one point, I came upon a series of curves, which being a bit deeper, allowed the water to pond. It was not running and none too fresh, but it was water. I noticed these two turtles on a log, probably a slider of some kind and a cooter. They seemed to be annoyed at one another.
We continued easing through the forest, moving slowly and stopping to listen and look occasionally. I photographed Bob standing next to a large swamp chestnut oak.
We found a bit of intriguing scaling here and there, but no large concentrations. This dying sweetgum snag is a good example. (Note the large insect at the upper right. We have not been able to identify it.)
At about one o’clock, we’d just kept walking through “lunch hour”, we decided to take a break. While we were snacking and rehydrating, I performed another series of ADKs followed by playbacks. After about an hour, Bob and I once again compared notes, and once again we had heard a pair of kents, and a single DK. I have to note that nothing we heard appeared to be a direct response to the recorded kents of the anthropogenic double knocks. While I was sitting there, I made this picture of a Red-headed Woodpecker.
We finally came to a corner with an adjoining piece of private property. As the property line was on a direct bearing for the truck, and was “only” a mile through unexplored terrain, we decided to take a chance even though terrain sometimes imposes obstacles. Fortunately for us (we had covered about six total miles previously) the terrain wasn’t bad at all, and other than a couple of hills to climb, the walk was pretty easy. On the way home, we stopped and picked up dinner at a local BBQ joint that has become something of a Project Coyote tradition.
Day 3 – October 11, 2014
On the way to the search area this morning, Bob and I, feeling a bit peckish, decided to stop at one of the convenience stores on the way. We were a bit mystified to find this sign in the window:
Being a proud son of Louisiana, I’m well aware of our love of foods that are considered a bit, ummm unconventional, but even I was a bit taken aback at the prospect of frying chicks…
We arrived at our entry point about ten minutes after first light and headed into the forest. This particular area Mark has discussed a number of times – a couple of hundred yards from the parking area one encounters a tornado blow-down track that is approximately 400 yards wide. This area is unbelievably difficult to traverse – large boled trees scattered like a giant’s game of pick up sticks, thick, almost impenetrable thickets of new growth, blackberry vines and saw briars, as well as the usual random sloughs, and cutoff stream channels.
It took us nearly an hour to make the half-mile to the location of the snag where photos, discussed in previous posts by Mark, were taken. My express purpose was to place one of our new Plotwatcher Pro cameras in this location. New growth of limbs and underbrush made this deployment a bit more complex than the last time. Bob trimmed intervening vegetation while I programmed, set up and started the camera.
After all this work, I used the camera’s Aimcheck function to make sure that the cam was placed optimally. We then proceeded to follow the bank of the main channel downstream. It should be noted that the stream is not running. In all my years of coming to this area, as a hunter, and searching for ivorybills, I have never seen it this dry.
We came to a familiar ponded slough where Mark and I have often stopped and rested for a few minutes. One of the larger trees, a 3.5 ft. DBH water oak had blown down since the last time Mark and I had visited the area in April. The tree still had leaves on it, though they were dry and brown, and the bole and upper branches had no sign of woodpecker workings. I believe that this tree was blown down on or around July 4th as that was the last time severe weather passed through the area. As they are very light and easy to carry, I had an extra Plotwatcher Pro cam with me. Taking advantage of this opportunity, I deployed the camera with a good view of the bole and top – hopefully this tree will attract insects, and soon thereafter woodpeckers feeding on them.
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.
As we were leaving, I determined to blaze a better trail through the blowdown area. Following a straight bearing on my GPS, I used a hatchet and snips to carve a path through the heavier ground cover. Perhaps crossing will be a bit easier next time.
On the way out of the forest Bob and I were treated to one last encounter. We came across this Buttermilk Racer sunning itself on the road. While not endangered, this snake is uncommon and seldom seen. After taking a few photos of him, I tapped his tail with my foot, encouraging him to seek a safer place out of the roadway.
I really enjoyed Bob Ford’s visit – he is a skilled woodsman and birder, and his insights as a professional wildlife scientist are greatly appreciated. I am looking forward to Mark’s next trip – hopefully over the Thanksgiving holiday.
Also, Mark and I would like to thank The Rapides Wildlife Association, and another donor “MC”, for their much appreciated and unsolicited assistance in purchasing our new trail cams, memory cards, and batteries.
A note from Mark: Frank captured some of the possible kent calls on his recorder. They are faint, and it may not be possible to tease any detail out of them. He may do a follow-up post if anything of interest can be gleaned.
As always, my time in our search area was very productive – inspiring new insights and ideas and producing suggestive but inconclusive evidence that Ivory-billed Woodpeckers are present in this location and have been for years. The weather was considerably more cooperative this trip than on the two or three preceding ones, although temperatures edged toward the uncomfortable – mid 80s and humid from Tuesday-Friday – and rain limited field time on Saturday and Sunday. I was alone from Tuesday-Thursday, and Frank Wiley joined me from Friday-Sunday. Later this week, I’ll post a day-to-day log that includes more about possible encounters and some additional images,
For reasons that should become clear, we are starting to think there may be a home range in an area of over four square miles (and possibly considerably more than that), much of which we have not yet explored, and some of which is very difficult to reach – a two mile walk from the nearest road and bisected by deep sloughs and streams. We have some reason to suspect that this range has been used for a number of years. This is in very mature bottomland forest, logged between 1905 and 1915, and it includes the stand of sweet gums where we found a cavity cluster last year.
Also on this trip, we did more experimenting with playbacks; I actually began the experiment shortly before I left for Louisiana, with a Pileated Woodpecker in my yard outside New York City. She responded with considerable agitation to my playback of Pileated calls and drums – calling and flying over at very close range while looking directly at me. She did not react at all to playback of ivorybill calls and pounding from the Singer Tract (the iBird Pro selections). Several species in our search area seem to react to ivorybill playbacks. Pileated, Red-bellied, and Red-headed Woodpeckers frequently react with drumming and scolding. In one instance, a calling Pileated Woodpecker went silent and flew away immediately after a playback. Barred Owls will often call immediately after, as will American Crows. In one case, a pair of crows came in to within 80 feet, apparently to investigate; in another, a Red-shouldered Hawk did the same.
There were three instances of possible ivorybill interaction with or response to playback. Two of them were very weak possibles, meriting only this passing mention. The third was a little more interesting and will be discussed in the day-by-day account. We will continue the experiment, both in Louisiana and New York (to see if and how various species react). We’ve recently been informed, by “Motiheal” from ibwo.net, that a Red-headed Woodpecker in Virginia approached in response to the playback of five kents.
One of the reasons we’re optimistic about having pinpointed a home range is the abundance of feeding sign in the area. In addition to the work sign from this area discussed in previous posts, there’s an abundance of older work, like this scaling on a hickory snag.
According to Tanner (p. 47), “Trees and limbs almost two years dead have lost almost all twigs, some small branches, and bark is loosened on some small branches.” Of course, the decay process is not as linear as Tanner’s description implies, and scaling of bark itself hastens the loosening of whatever remains. Thus, on scaled branches and boles, bark is likely to have loosened considerably unless the work is very fresh. Still, the presence of leaves and/or twigs is a strong indicator of recent death, perhaps even more so on blowdown, for which the decay process is likely hastened by proximity to the ground. In terms of more recent work, I found two sweet gums with sign on large high limbs, perhaps the most dramatic scaling that closely matches Tanner’s description we’ve found to date. Not only is it very extensive; the scaled limbs are quite recently dead. While it’s not possible to test the tightness of the bark, the presence of leaves in the case of the more recent scaling and twigs with buds in the case of the somewhat older work suggest that the limbs died within a six months to, at most, two years. It has been suggested that ivorybills are largely birds of the canopy that seldom if ever feed near the ground and that this behavior might account for the difficulty in obtaining clear photographs. Despite the fact that Allen and Kellogg observed a female bird feeding on the ground like a Flicker, and Tanner himself reported observations of foraging close to the ground, the idea that the species is limited to the canopy has become a kind of conventional wisdom. As I’ve discussed in previous posts, I don’t accept this notion and much of the feeding sign we’ve found has been low on standing trees and snags and on blowdown or slash. In the last trip report, I discussed feeding sign found on recently downed sweet gums (just outside of what we believe to be the hot zone, although possibly within it if it is larger than we currently suspect). On this trip, I found over two dozen examples of extensive bark scaling on downed sweet gum tops and limbs. This work was so commonplace that photographing additional examples seemed redundant. In all cases, the blowdowns were recent and involved very freshly dead wood. At least some leaves were still attached, making it likely that these limbs and tops had fallen in the last six months to one year. In the hot zone, I found only two sweet gum tops or large limbs that had not been scaled. Most of the scaling was recent to very fresh, probably one or two days old in one instance (unfortunately, it had rained the night before, so any scat had been washed away.) I do not believe that all of this is the work of ivorybills. Nonetheless, I suspect that much of it is, due to its abundance and extensiveness and in light of Tanner’s study and the preference he found in the Singer Tract ivorybills for recently dead and dying sweet gums (this even though I believe Tanner overstated this preference and did not sufficiently account for specific conditions in the Singer Tract).
I did not find this type of work in brief visits to areas outside the hot zone, where it was ubiquitous; nor have I seen anything quite like it elsewhere. I did not see anything like it on other species of downed trees; the only partial exception was some scaling on longer dead parts of a live downed hickory. As an aside, it’s worth mentioning that the species of hickory in our area were not present in the Singer Tract, although their congeners, pecans and water hickory were. Unlike Tanner, we’re finding scaling on hickories that likely exceeds their relative abundance. We’re also finding considerably less scaling on various oak species.
In addition to the work on freshly downed sweet gums, I found two standing, recently dead young sweet gums that had been worked on in unusual ways. Both showed signs of infestation by insects that bored into the heartwood. Both had been very heavily scaled, one with minimal excavation only around the insect tunnels. The other had been hacked up in a way that, in the words of several people, looked as if someone had taken a hatchet to it; the wood was hard and not at all punky. Whatever did this work chopped through a small branch to the point where it broke off and almost severed the top of the tree as well.
In his report on Cuban ivorybills, George Lamb described something similar:
Soon after we observed a female ivory-bill . . . feeding on the dead branch of a Hilacho tree (Torrubia obtusata) in a small stand of hardwoods. Suddenly the branch broke off while she was still perched on it . . . The Hilacho limb previously mentioned as breaking while being fed on, represents a type of feeding which was neither scaling nor digging. The limb was vertical and had probably originally been about three inches in diameter. Possibly it had once been scaled, but when recovered showed evidence of feeding to the extent that hardly anything was left. The wood was very punky and hand been chipped away from the perimeter to of the limb all along it’s 2 1/2 foot length. The chips, some of which we gathered, were long and splintery appearing, and were riddled with beetle larvae “tunnels”.
Our broken branch is approximately 2″ in diameter, while the top appears to be more than 3″. Unlike the Hilacho tree, the wood on this sweet gum was hard, not punky.
While I suspect that some of the work on these trees, the very targeted work on the limbs (small rectangular scaling/digging), may have been done by Hairy Woodpeckers, the bulk of it is extremely unusual, inconsistent with any Pileated Woodpecker work I’ve ever seen and with Tanner’s description of that species’ foraging preference for longer dead wood; the type of prey is consistent with what would be expected for ivorybills. While the work on ‘hatcheted’ sapling doesn’t meet the diagnostic criteria we’ve developed over the years, we think it highly likely that this is Ivory-billed Woodpecker work. The scaling on the other small sapling is generally consistent with our criteria, although it has some very limited excavation, clearly aimed at expanding existing tunnels, rather than digging into the wood in the manner typical of Pileated Woodpeckers. Again, from the Lamb report: At one point she was only about 25 feet away while she was feeding around the base of a small pine. She began working “barking” this tree around 30 inches from the ground and slowly worked her way up to the top.
Stay tuned for the second installment, which will also include details of a sighting Frank Wiley had on Friday, April 3.
As most readers know, I have been very focused on feeding sign, and specifically on bark scaling, for several years and believe I have identified a diagnostic type of work that is beyond the physical capacity of any other woodpecker species. I have been far less focused on excavation because I was convinced that there was no way to distinguish between Pileated and Ivory-billed Woodpecker digging.
In fact, Frank Wiley and I have had a long-running joke about Plate 11 in Tanner and have always wondered why he included it. Based on some feeding sign we’ve found recently, another look at some sign found in May, and a look at online imagery of both Campephilus and Pileated excavations, I suspect that certain types of excavation are suggestive if not diagnostic.
Tanner wrote, “When Ivory-bills dig, they chisel into the sap and heartwood for borers like other woodpeckers, digging slightly conical holes that are usually circular in cross section (Plate 11).”
When I returned from Louisiana in November, I was struck by certain similarities between this excavation:
which I discussed in the most recent trip report, and Plate 11, especially the hole at the upper right and the third hole from the bottom in the plate. I was also impressed by the bill marks at the edges of these holes and by their depth. I then started looking at images from Bill Benish’s Flickr Campephilus group photos and was struck by the similarities, for example:
I then went back to a photograph I took in May of some excavation that struck me as being unusual at the time, although I couldn’t have specifically explained why.
The appearance of some of the holes is strikingly similar to the Pale-billed Woodpecker excavation shown here.
The work in the upper part of the image that’s partially cut off looks more consistent with typical Pileated excavation.
While I’ve not examined digging with nearly the attentiveness that I’ve devoted to scaling, These workings do not look like typical PIWO excavation, examples of which can be found:
Magellanic Woodpeckers, which are more PIWO-like behaviorally and anatomically, appear to excavate in a way that’s more similar in appearance to typical PIWO work, but even Magellanic excavation often seems to have a more jagged and more rounded look than does PIWO.
I wonder if the apparent differences might have to do with preferred food sources – termites and ants for pileateds and beetle larvae for ivorybill. General deep digging is an effective feeding strategy for the former; while more targeted excavation would be more efficient for the latter. Note that the PIWO work in the first image above seems to be targeted (and was likely focused on larvae) but has a much sloppier appearance.
Today, I found another tree with this type of work, not far from the area that we’ve just started to explore and think is very promising. Below are two views of the work. One potentially significant element is that the larger holes appear asymmetrical (Tanner notwithstanding) and more skewed in orientation than typical Pileated Woodpecker foraging trenches, which would be consistent with their being dug with more lateral blows.
While I’m not prepared to suggest that there’s a diagnostic when it comes to this type of feeding sign (and my comments about the excavation from last May are considerably more speculative) , I am starting to think it may be and that there may be a gestalt that is at least suggestive of ivorybill to the experienced and careful observer.
Edited to add: to reiterate, this is an evolving hypothesis, subject to revision or abandonment. I will need to start looking closely at work outside of suspected ivorybill areas and at the work of other Dryocopus woodpeckers.