What’s in the Cavity? A Possible Second Bird in a Couple of Old Trail Cam Photos

Regular readers are no doubt familiar with some of the images shown below. The “neck bird”, which was photographed in our old search area in August 2009, has been discussed in a number of posts. I think it likely shows a female Ivory-billed Woodpecker, something that became clearer once I satisfied myself that what appeared to be red in the crest (in the wrong place for either Pileated or ivorybill) was likely an artifact and that the crest appears to be all black, as shown in the enhanced image below. The original captures (the first taken a minute before the neck bird appears and the second showing the neck bird) are immediately below that for those who haven’t seen them.

IMG_1096-Edit-Edit-Edit-Edit-Edit-Edit-Edit-Edit-EditTopaz+processed+neck+bird+copy-magic copy 2

Processed Detail of Image 1096, August 11, 2009

Years after the capture and probably after the first post about this image in 2014, I noticed that an object suggestive of a light colored bill was visible in both frames, apparently protruding from the lower cavity in the snag to the right of center. While I have shared this information privately with a number of people and did a vague Facebook post about it a couple of years ago, I’ve hesitated to blog about it or discuss it in detail. That changed after I showed it to Jay and Erik before we parted company on my last trip to Louisiana. When Erik suggested that the object might be a vine or some other intervening vegetation, I decided to go back through my files. I discovered that Frank had sent me several additional captures from the same deployment. I examined these frames and found that the apparent bill was absent from all of them.

 

Below are details from frames 1095 and 1096 showing the apparent bill, which changes position slightly from one frame to the next. The time lapse interval between images was 1 minute. Again, the cavity in question is the lower one (below the fork) in the snag to the right of and behind the one on which the neckbird is seen in 1096. These snags are black willows (Salix nigra), and the neck bird snag (with the large cavity apparently being used by a squirrel) fell between November 2009 and January 2010. I’m also posting the close-ups in tiled mosaic format so they can be viewed side-by-side.

For this round of image processing, I used Let’s Enhance, which enabled me to retain a large format for cropped and zoomed versions.

IMG_1095-Edit-2-EditTopaz+processed+neck+bird-magic. copy

Detail from 1095 – Note apparent light colored object (possibly a bill) apparently protruding from an bisecting the lower cavity

 

IMG_1096-EditTopaz+processed+neck+bird-2-magic copy

Detail from 1096, captured one minute later. Note slight change in position of the possible bill.

Next are two details from images captured a few days later. The possible bill is nowhere to be seen. The same is true for the other captures from this deployment. Thus intervening vegetation and artifact can be ruled out.

2135DetailEnhanced

Detail from image 2135, captured August 14, 2009. Note the absence of the apparent bill that appeared in images 1095 and 1096 captured three days earlier.

2507DetailEnhanced

Detail from Image 2507, captured on August 16, 2009. Again, note the absence of any object in the lower cavity.

To summarize, the following two photos show what appears to be a bill in the cavity:

2009-08-11 7:48 am  (image 1095.jpg)

2009-08-11 7:49 am  (image 1096.jpg – the neck bird photo)

The following photos show a cavity with no apparent bill:

2009-08-14 6:19 am

2009-08-14 6:20 am

2009-08-14 6:21 am

2009-08-14 4:06 pm

2009-08-14 4:07 pm

2009-08-15 6:20 am

If this is a bill, it appears to be large and light colored, consistent with Ivory-billed Woodpecker. Both Erik and I noticed that, in frame 1095, a topmost part of the white dorsal stripe also may be visible. When Jay first saw the photos, he was reminded of the Neal Wright photos from Texas. Some images from the Singer Tract also come to mind.

 

Thus, this apparent bill resembles those of known ivorybills in cavities – in size, shape, orientation, and contrast. It is present only in frames 1095 and 1096 (the latter of which shows another possible ivorybill); it changes position over the course of a minute, from one frame to the next. There is no way to be sure images 1095 and 1096 show an Ivory-billed Woodpecker in a roost hole, but these facts, especially taken together, suggest that they may.

When I look back at what transpired in the old search area between August 2009 and November 2010, when the adjoining parcel was logged, it’s extraordinary. I may revisit those events in a future post or two.

For now, I’ll close by tying this into the Bits and Pieces series. The old search area is not one that would be deemed suitable under most habitat models. The images above were captured in a stand of black willows at the edge of a bean field. The other trail cam capture, where I had a sighting, was also within perhaps 30 yards of that field. When I look back at my assessment of the habitat from the time, I think I somewhat naively overstated its quality; however, there was a good deal of dead and dying timber, and it was in close proximity to several much larger habitat patches. If we did indeed capture ivorybills with our trail cams, their presence in this area may point to how the species has been able to adapt to more fragmented habitats.

Thanks to Erik Hendrickson for his input on this post and his help in making it clearer.


Bark: An Exegesis

Introduction:

According to Tanner, scaling bark was the Ivory-billed Woodpecker’s primary foraging strategy during breeding season in Louisiana. Tanner wrote that the ivorybill is “capable of easily scaling away heavy bark that other woodpeckers could not loosen.” (Tanner 1942). All woodpeckers in genus Campephilus have specific anatomical characteristics that enable them to forage in this specialized way (Bock and Miller 1959). Following Tanner, most post-Singer Tract search efforts have looked for feeding sign as an indicator of presence. Because Tanner’s descriptions are somewhat vague and many of the photographs showing feeding sign are poor, these efforts have tended to focus on decay state and bark adhesion without taking bark characteristics and tree species sufficiently into account. I posit that tree species and bark and wood characteristics are key factors that should be considered. I further posit that extensive bark scaling on live and recently dead hickories (genus Carya) may be beyond the physical capacity of the Pileated Woodpecker.

Discussion:

As all regular readers know, I’ve been somewhat obsessively focused on bark and bark scaling since my earliest years of ivorybill searching. The reason for this interest is simple: it’s how Tanner found ivorybills or inferred their presence when he couldn’t find them (Tanner 1942). Unfortunately, as discussed in a number of posts, Tanner’s descriptions are somewhat opaque, and most of the published images of feeding sign, including those in the monograph, are not very illuminating. Indeed, some of them are consistent with pileated work that we’ve documented. Plate 8, shown below, is a prime example. The caption reads, “Ivory-bill feeding sign on a slender limb”.

021_jpg

Tanner’s Plate 8, Courtesy of the Division of Rare and Manuscript Collections, Cornell University Library

imgp4248

Pileated Woodpecker feeding sign on a slender limb

Early on in my study of this subject, I hypothesized that certain kinds of bark scaling on hardwoods might be beyond the physical capacity of the Pileated Woodpecker. I still believe this to be true, a view that is supported by what we’ve documented for pileated and by numerous examples of pileated scaling from online sources. At the same time, the details of what types of work might belong in this category have shifted somewhat, especially as it has become clear that Pileated scaling can look like what’s shown in Plate 8 and that pileateds will scale bark from recently dead sweet gums.

This is not to suggest that ivorybills never scale small and medium-sized branches in a similar manner. According to Tanner they did so frequently; however, I have been focused on what may be diagnostic for ivorybill. It seems likely that there is considerable overlap between ivorybill and pileated work when smaller branches are involved (at least on sweet gums).

The sequences we obtained showing pileateds scaling a sweet gum limb have inspired me to look more deeply at the characteristics of hardwood bark and pursue some research avenues that I hadn’t considered previously. I’ve linked to some of the sources in recent posts, but I’ve had some additional insights that seem important enough to share. Every time I think I’ve run out of things to say on the subject, something new crops up.

Like virtually everyone else, I’ve followed Tanner and focused on two bark characteristics, “tightness” and thickness, but it recently struck me that other features might be important as well. And the literature, mostly from the lumber industry, supports this idea.

Tanner suspected that the Singer Tract ivorybills preferred sweet gums and Nuttall’s Oaks because the bark is thinner, and the thinner barked limbs had “more borers” than thick barked ones. While abundance of food was likely a factor, I suspect that, at least with respect to sweet gums and possibly Nuttall’s oaks, ease of scaling and access to food played a role.

It’s important to point out that in live trees, hardwood bark adhesion varies seasonally, with bark becoming tighter during dormant stages and looser (with considerably less variation from species to species) during the growing season. Bark is often if not always tighter on recently dead trees than on live ones (Stokland et al. 2012).

In addition, “The structural and chemical traits of dead wood, inherited from the traits of living trees, are also major drivers of wood decomposition and these traits vary greatly among tree species.” (Cornellisen et al. 2012). The authors of the linked paper point out that other factors, including size and site, can also contribute to the way that bark loosens post-mortem, but specific traits seem to be paramount, especially since the scaling we deem to be suggestive, whether on standing or downed wood, is on trees that are alive or are recently dead. Because the scaling has a very distinctive appearance, we also deem as suggestive hickory snags and stubs that appear to have been scaled some years ago, even if they are in a considerably later stage of decay overall. Bark attached to hard wood on these longer dead stubs and snags often remains tight for 3 or more years after death.

A 1978 report, entitled Bark and Wood Properties of Pulpwood Species as Related to Separation and Segregation of Chip/Bar Mixtures examined bark morphology and strength properties in 42 different pulpwood species and identified factors that impede the mechanical removal of bark from logs. These include: cellular structure, bark adhesion, bark strength, bark toughness, wood toughness, specific gravity/density, and moisture content. (Institute of Paper Chemistry 1978) One caveat about this report: a subsequent paper gives the sample size for each species, and in many cases (including sweet gums) it was only 2 (Einspahr et al. 1982)

It may be counterintuitive, but the authors found that shagbark hickory was far and away the most difficult bark to remove. (The tightly adhering layer is thin, beneath the dead bark that gives the species its shaggy appearance.) One key finding was that:

“Morphologically, the presence of fibers increases inner bark strength and, when sclereids (a type of cell) are present, bark strength is decreased. Inner bark strength, in turn, has a major influence on hardwood wood/bark adhesion. The multiple regression equation employing wood toughness and inner bark strength accounts for 72% of the wood/bark adhesion variation encountered.”

Sclereids are virtually absent in hickories (Nanko 1980) and a few other species that don’t approach the hickories in bark strength and bark and wood toughness (Eastern cottonwoods, yellow poplars, white ashes, and black willows). These tables are particularly illustrative:

screen-shot-2017-02-24-at-9-57-50-am
woodchart

Shagbark hickories are the extreme outlier in this study, in terms of adhesion, as well as in terms of inner and outer bark toughness and strength; there are very few shagbarks in our search area, and we have never found scaling on one. I have been unable to find specific information about bitternut hickory bark strength or toughness, but the industry’s debarking problem applies to all species in the genus Carya due to the near absence of sclereids in conjunction with the other factors. Moreover, the industry does not differentiate among hickory species (Timber Mart South 2016). This 1996 paper is worth quoting at length in this regard (full text is not readily accessible):

The amount of published literature dealing with hickory debarking is very limited. Often it is only mentioned as an example of one of the hardest tree species to debark. One study quantified this by measuring the strength of the bark-to-wood bond of 42 hardwood species, including hickory. According to Einspahr et al., the dormant season bark-to-wood adhesion for hickory is greater than 3000 kPa, which is a tenfold difference from the growing season and nearly three times as great as the dormant season wood/bark adhesion for quaking aspen (Populous tremuloides, L.), a species considered to be extremely difficult to debark in the northern United States.

Einspahr et al. also microscopically examined the failure zone in an attempt to correlate morphological differences with bark-to-wood adhesion. For hardwoods in general, they found that during the growing season, failure occurred in the cambium or in the xylem just inside the cambial zone. Conversely, dormant-season failure occurred in the inner bark. They also found that fibers in the bark increased the inner bark strength while sclereids decreased inner bark strength. Hickory bark can contain between 15 to 20 percent fiber and contains less than 0.05 percent sclereids.

While these studies have confirmed that hickory is difficult to debark, they have not addressed possible solutions to the problem. As a result, hickory is often left behind during harvesting, reducing the total usable fiber from a given stand and, over time, increasing the percentage of the species in the hardwood resource, compounding the problem of future harvests.

When a tree dies, the bark eventually loosens and detaches naturally as the cambium decays. After felling, the cambium remains alive until it has consumed all available food or dries out. Moisture loss, while causing cambial death, initially greatly increases the strength of bark attachment because additional bonding between fibers occurs as the secondary valence bonds with water are broken (Belli 1996).

Thus, even though hickory bark adheres less tightly than sweet gum bark during the growing season, it seems likely that it’s harder to scale year round, given its much greater wood and bark strength and toughness. It is also clear from my observations that sweet gum bark loosens far more rapidly than hickory bark post mortem. Note that we have found fresh scaling on both live and recently dead hickories.

Based on specific gravity of the bark – averaging 0.72 for shagbark and 0.60 for bitternut – and bark moisture content – averaging 34% of dry weight for shagbark, and 60% for bitternut – it seems likely that bitternuts are somewhat easier to debark than shagbarks but considerably harder to debark than virtually any other tree species in our search area.

Comparing bitternut hickories to other species, most oaks have a considerably higher average moisture content in their bark (Chestnut and Southern red, including Nuttall’s oaks, are exceptions) and similar specific gravities. Sweet gum bark has an average specific gravity of 0.37 and an average moisture content of 91% of oven dry weight. (Schlaegel and Willson 1983, Miles and Smith 2009). But oaks and sweet gums have sclereids, and sweet gums and all tested oak species score far lower on bark toughness and strength than shagbark and, by inference, bitternut hickories. Sweet gums and the tested oak species are fairly similar in these regards, but I suspect that the higher density and lower moisture content in oak bark makes it harder to scale and may mean that oak bark adheres more tightly than sweet gum bark for a longer period after death.

I posit that when it comes to woodpecker scaling, dormant season bark adhesion, inner and outer bark strength, and inner and outer bark toughness are all relevant factors. We know that Pileated Woodpeckers remove sweet gum bark with some difficulty and that even on medium-sized limbs, they are not consistently able to remove bark cleanly down to the sapwood. It’s also clear that bitternut hickory bark is very difficult to remove, second only to shagbark hickory in our search area. This further reinforces my view that the work on hickories is not the work of Pileated Woodpeckers.

Click here and here for examples of the hickories that are scaled in a manner we hypothesize is diagnostic for Ivory-billed Woodpecker. Also be sure to watch this YouTube video of a Crimson-crested Woodpecker (Campephilus melanoleucus) foraging. (Thanks to Phil Vanbergen for finding the clip and the scaled hickory at the second link.) I’m reposting the link to the video here because I think it very clearly illustrates many of the characteristics we associate with Ivory-billed Woodpecker work on hickories, although the species of tree being fed on is unknown. Note the striking similarity in appearance and also that the work of the substantially smaller billed Crimson-crested is not as clean around the edges as the work we’re ascribing to ivorybills.

There were no bitternut hickories in the Singer Tract, but there were congeners – pecans and water hickories. Tanner observed ivorybills scaling on these species twice and digging once. For pileateds, there were 4 instances of digging and none of scaling, as opposed to 5 scaling and 9 digging on sweet gums. The relative abundance of water hickory and pecan at Singer was 2.7%; approximately 10% of the trees in our search area are hickories, and hickories are second only to sweet gums in terms of the number of scaled trees we’ve found. While Tanner’s is obviously a minuscule data set, it may support the hypothesis that live and recently dead Carya bark is too tough for pileateds to scale extensively, if at all.

There are a number of hardwood species found in potential ivorybill habitat that are somewhere between sweet gums and hickories in terms of how easily scaled they may be and how soon after death bark decay and loosening set in – eastern cottonwoods, black willows, water tupelos, some oak species, red maples, green ashes, honey locusts, persimmons, and elms – in these species, it seems likely that close examination of the scaling and bark chips can provide some clues.

Conclusion:

Previous Ivory-billed Woodpecker searches have focused on bark adhesion and state of decay when considering scaling as possible foraging sign. Bark morphology, dormant season adhesion, inner and bark outer strength, and inner and outer bark toughness, and wood toughness are all relevant to the ease with which bark can be scaled from live and recently dead hardwoods. Specific gravity and moisture content are also factors. Bark from trees in the genus Carya is difficult to remove industrially, and members of this genus are likely the most difficult trees to scale throughout the historic range of the ivorybill. Since Pileated Woodpeckers scale sweet gum branches with some difficulty and do not consistently remove bark down to the sapwood, it may be beyond the physical capacity of Pileated Woodpeckers to scale hickories extensively and cleanly, while leaving large pieces of bark behind. Extensive work on hickories that has a distinctive appearance may be diagnostic for ivorybills; this distinctive appearance of this scaling may also be the key to recognizing Ivory-billed Woodpecker foraging sign on other species.

Lagniappe:

This may be no more than an aside, but it may be a relevant data point. I recently observed a Pileated scaling briefly on a live 14″ DBH Norway maple in my yard near New York City. The photos show that the sap is flowing. The appearance of the scaling is exactly what I’d expect for Pileated, with strips about half an inch across. Norway maple may be a decent stand-in for sweet gum; while its bark has a higher specific gravity, 53 as opposed to 37, the moisture content of the bark is almost identical, 91% as opposed to 90%.

imgp4298imgp4300imgp4303
References Cited:

Bock, Walter J. and Waldron Dewitt Miller, The Scansorial Foot of the Woodpeckers, with Comments on the Evolution of Perching and Climbing Feet in Birds, American Museum Novitates, #1931, 1959

Belli, Monique L., Wet storage of hickory pulpwood in the southern United States and its impact on bark removal efficiency, Forest Products Journal. Madison 46.3 (Mar 1996): 75.

Cornelissen, Johannes H.C., Ute Sass-Klaassen, Lourens Poorter, Koert van Geffen, Richard S. P. van Logtestijn,Jurgen van Hal, Leo Goudzwaard, Frank J. Sterck, René K. W. M. Klaassen, Grégoire T. Freschet, Annemieke van der Wal, Henk Eshuis, Juan Zuo, Wietse de Boer, Teun Lamers, Monique Weemstra, Vincent Cretin, Rozan Martin, Jan den Ouden, Matty P. Berg, Rien Aerts, Godefridus M. J. Mohren, and Mariet M. Hefting, Controls on Coarse Wood Decay in Temperate Tree Species: Birth of the LOGLIFE Experiment, Ambio. 2012 Jul; 41(Suppl 3): 231–245.

Einspahr, D.W, R.H VanEperen, M.L. Harder et al. Morphological and bark strength characteristics important to wood/bark adhesion in hardwoodsThe Institute of Paper Chemistry, 1982: 339-348.

Institute of Paper Chemistry, Project 3212, Bark and wood properties of pulpwood species as related to separation and segregation of chip/bark mixtures, Report 11, 1978.

Miles, Patrick D. and W. Brad Smith, Specific Gravity and Other Properties of Wood and Bark for 156 Tree Species Found in North America, United States Department of Agriculture, Forest Service. Northern Research Station, Research Note NRS-38, 2009.

Nanko, Hiroki, Bark Structure of Hardwoods Grown on Southern Pine Sites (Renewable Materials Institute series), Syracuse University Press, 1980.

Schlaegel, Bryce E. S and Regan B. Willson, Nuttall Oak Volume and Weight Tables, United States Department of Agriculture, Forest Service. Southern Research Station, Research Paper SO-l 86, 1983

Siry, Jacek, ed., Species Detail Report, Timber Mart-South, 2016

Stokland, Jogeir N., Juha Siitonen, and Bengt Gunnar Jonsson, Biodiversity in Dead Wood, Cambridge University Press, 2012

Tanner, J.T. The Ivory-billed Woodpecker,National Audubon Society, 1942.

Thanks to Fredrik Bryntesson, Steve Pagans, Chris Carlisle, and Bob Ford for their help with this post.


Feeding Sign: Further Reflections and Clarifications

I’ve created a page that expands on this post and should provide a good introduction to our thinking about the three most intriguing types of feeding sign, with images from the second and third categories. Think of this post as the shorter version.

Over the years, I have written a great deal about bark scaling and the types of work I think are diagnostic for Ivory-billed Woodpecker; however, I don’t feel that I’ve been effective enough at conveying the nuances of what I look for in situ. I’m going to try a somewhat different approach using images that have been posted previously. I will be focusing on the category of bark scaling that I think is most compelling for Ivory-billed Woodpecker. I hope that the tiled mosaic layout will make it easier to get my points across.

The scaling I find most compelling for ivorybill is on hickories, mostly or all bitternut hickories (Carya cordiformis).  This work represents a relatively small subset of the suspected ivorybill feeding sign we’ve found, as would be expected given that under 10% of trees in the area are hickories. It is not the type of foraging sign that Tanner emphasized, and I’m not suggesting that scaling on boles is the ivorybill’s predominant foraging strategy. I emphasize this work because it has a distinctive appearance, one that differs dramatically from presumed Pileated Woodpecker foraging sign on the same species.

The above images show presumed Pileated Woodpecker work on a recently dead bitternut hickory found last February. It seems reasonable to infer that this is Pileated work because of its extensiveness and the abundance of fresh chips at the base of the snag, suggesting the work was recent and was done by a large woodpecker. Some readers might be inclined to think of this as “scaling”, when in fact it is shallow excavation. The small size of the chips and the fact that some of the chips are sapwood, not bark, support this idea. Contrast the roughened appearance of the sapwood with the clean bark removal in the images below. Also contrast the extensiveness; while the work shown above involves fairly large areas, it pales in comparison to the very extensive scaling shown below.

Edited to add: I think squirrels can also be ruled out for this work due to the involvement of the sapwood, apparent bill marks, and the presence of insect tunnels.

I think that all of the images immediately above show Ivory-billed Woodpecker work, most of it fresh. The similarity in general appearance from tree to tree should be self-evident. This type of scaling can be found from within approximately one foot off the ground to the upper parts of boles. Large Cerambycid exit tunnels are visible in the sapwood. Bark chips, when found, were large, and the only hints of excavation involved targeted digging to expand the exit tunnels. It’s worth noting that the Hairy Woodpecker in the trail cam photo above spent several minutes removing a quarter-sized piece of bark. The Pileated Woodpecker also spent several minutes on the tree; it pecked and gleaned and looked around but did no excavating or scaling.

Bitternut hickory wood is “hard and durable” and the bark is hard and “much tighter than on most other hickories.” The bark is sometimes described as being thin, but this appears to apply to young trees only. On mature boles, it can be .5″ thick or more.

Due to these qualities, the decay process for hickory snags is often more gradual than for other species, especially in higher and dryer areas. This means that the wood can stay hard and the bark remain tight for as long as three years; such is the case with the tree shown in the penultimate image above. This has enabled me to do periodic checks on some of the snags, and in most instances, they have shown little or no indication of further woodpecker work for extended periods, until the wood starts to soften and excavation becomes easier. Whatever is doing this work seems to be hitting the trees once or twice without returning or, less frequently, to be making visits several months apart. I think this suggests a thinly distributed, wide-ranging species as the culprit, and in my experience, Pileated Woodpeckers tend to return to feeding trees on a regular basis.

In my view, this very specific type of work is diagnostic for ivorybill and is beyond the physical capacity of the Pileated Woodpecker. I’d suggest that similar appearing work on other tree species should be considered strongly suggestive. When it comes to the high branch work that Tanner emphasized, it is more difficult to rule out Pileated Woodpecker. As discussed in several recent posts, this type of foraging was the predominant one during breeding season and immediately after fledging young, at least for the John’s Bayou family group. Thus, for work higher on trees, where bark is thinner and tightness cannot be assessed, abundance is likely a key indicator. From this perspective, it may be significant that our friends the Carlisles who are searching in the Pascagoula area have found only two sweet gums with work that I consider to be intriguing and consistent with what’s described in the literature. By contrast, I found over 50 such trees in our area in the 2015-2016 season alone. Whether or not there are ivorybills in the Pascagoula, the difference between the Carlisles’ observations and ours is dramatic and suggests that something unusual is going on in the Project Coyote search area.

 


Old Singer Tract Images Compared with Two More Recent Ones (from Elsewhere)

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.

Ivory-billed Woodpecker w16-1-001 copy

© N. Wright/VIREO USA – Nest with adult protruding, slide mount dated 5/70 (apparently the duplication date). Poorly defined bird is apparently peering out of a cavity in the upper left of the trunk, below the fork.

Screen Shot 2016-06-14 at 10.07.18 AM

Ivorybills at Nest, John’s Bayou 1938, female’s head protruding from cavity

IMG_1119 (1)

Ivorybills at Nest, John’s Bayou, 1935, male’s head protruding from cavity

 

NestHolePix copy

Images from the Singer Tract and James T. Tanner’s Dissertation Courtesy of Courtesy of the Division of Rare and Manuscript Collections, Cornell University Library

 

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.

Screen Shot 2016-06-14 at 11.04.21 AM copy

Courtesy of the Rare and Manuscript Division, Cornell University Libraries

IMG_3547 Red Box

Trail cam photo with scaled tree in the foreground and suspected female Ivory-billed Woodpecker in red box, Nov. 2009

To enlarge the trail cam photo, click here.


Scaling Data 2012-2016

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.
Screen Shot 2016-06-08 at 8.09.41 AM
Totals

Sweet Gum (Liquidambar styracifula)

Sector 1:         46

Sector 2:         8

Sector 3:         51

                        105         (84.68%)        

~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

                           14         (11.29%)

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

                         5         (4.03%)

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.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Old Material, New Light: More from the Archives Part 2

In late December 2014, I wrote what I’ve described as a speculative post titled, “Is There a Way to Recognize Ivory-billed Woodpecker Excavation? In that post, I relied on Tanner’s Plate 11,

020_jpg

Tanner’s Plate 11, “Dead hackberry, fed upon frequently by Ivory-bills”. Courtesy of the Division of Rare and Manuscript Collections, Cornell University Library

a brief description from the monograph: “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)”, and online imagery showing the work of other Campephilus woodpeckers. Material found during my recent visits to Kroch library at Cornell lends some support to the ideas contained in that post, and so does T. Gilbert Pearson’s photograph of a tree that had been fed on by ivorybills. Holt:Pearson Tree

The archival material includes additional images of ivorybill excavation and a considerably more detailed description by Tanner in a document prepared for the Cuban search in the 1980s. The passage includes somewhat more detail on bark scaling than is found elsewhere, but more importantly it describes ivorybill excavations as “hard to distinguish from similar digging by the Red-bellied Woodpecker”.

IMG_1107

Courtesy of the Division of Rare and Manuscript Collections, Cornell University Library

This description may seem counterintuitive to some. Despite my own writing to the effect that ivorybill morphology may lead the species to dig less efficiently than pileateds and my references to targeted digging, I still had an underlying assumption that the size of the bird would correlate with the size of the dig and that ivorybill excavation would often resemble the familiar large furrows dug by PIWOs. While a couple of the holes in Plate 11 and in Pearson’s photograph may well involve the merging of more than one dig, it appears that ivorybill excavations are usually more targeted and that large furrows are not typical.

Also of interest for multiple reasons, including the observation of birds scaling very small limbs and of one feeding 5′ from the ground, are Tanner’s field notes from April 3rd, 1937.

IMG_1100

IMG_1101

Courtesy of the Division of Rare and Manuscript Collections, Cornell University Library

I’ll let the remaining images of known and suspected ivorybill excavations speak for themselves and will conclude with a few from our search area that seem consistent with known ivorybill work. While I’m nowhere near as confident about this material as I am about scaling, I suspect that finding excavations that are consistent with what ivorybills are known to have done in conjunction with scaling is suggestive.

I hope this material will be useful for other searchers. All images from the Singer Tract below are courtesy of the Division of Rare and Manuscript Collections, Cornell University Library. Most of these images were published in Tanner’s dissertation but have not been widely disseminated.

IMG_1112

OakNest copy

Ash Roost

'35 Nest Tree copy

1935 Nest Tree, Red Maple

RMC2006_0563

 

detail

1935 Nest Tree and Detail from a Different Perspective

And now some examples from our search area that resemble the existing images of known ivorybill excavation. This is not something I’ve focused on, so I’ve probably missed other examples.

IMG_0924_2IMGP1897

IMG_0854IMGP1579IMGP1476

IMGP1452

Image at bottom is a detail of the sweet gum snag above. I suspect that more than one species of woodpecker is involved.

There will be one or two more installments in this series, but the next post is likely to be a trip report, probably the last for this season.


Old Material, New Light: More from the Archives Part 1

I’m planning to do a few more posts drawing on material I’ve found in Kroch Library’s Rare and Manuscript Collection at Cornell. There may be an intervening post or two on  other topics.

While Tanner’s monograph is well-known, the reports he wrote for the Audubon Society at the end of each season are not publicly available, except in the archives. The contents of these reports call some conventional wisdom about the species into question.

First and perhaps least important, it seems to be commonly believed that the John’s Bayou birds were the only remaining ivorybills in the Singer Tract when Tanner visited in December 1941. They were indeed the only birds he saw, as noted in his report (the first document below); however, he found feeding sign in the Mack’s Bayou area and suggested that at least two more birds remained, one at Mack’s Bayou and another in Greenlea Bend. As I read the report, Tanner referenced Bick’s observation in August ’41 (discussed here), and the context suggests that he related it to the John’s Bayou family. Other interpretations are possible, including that this was another family group that was passing through the area, which would mean that the remaining 1941 population was even larger.

In Ghost Birds, Steven Lyn Bales provides a full accounting of Tanner’s population estimates, but earlier books by Hoose and Jackson gloss over the likely presence of the other birds. Hoose (p. 120) wrote that James and Nancy Tanner “maybe heard a third” at Mack’s Bayou. (The source of this information is not identified.) Jackson (p. 132) has Nancy Tanner seeing a male and a female in December 1941. Both Bales and Hoose are clear that she saw the pair in 1940; per Bales, the actual date was December 21.

While there’s no way of knowing whether the birds Bick saw were the John’s Bayou family, I suspect that they were. I also think it’s reasonable to infer, as Tanner did, that this group bred successfully in 1941 (possibly an important point given the disturbance to the habitat). If Bick’s birds were the ones from John’s Bayou, it seems the male disappeared sometime between mid-August and December. Given the consistent presence of this family group in the vicinity for nearly a decade, there’s perhaps a hint of wishful thinking in Tanner’s suggestion that the male “might have moved away” due to the logging.

Screen Shot 2016-05-06 at 7.42.47 AM

The next interesting tidbits come from a 1938 interim report that Tanner sent to the Audubon Society, under the terms of his fellowship (the document below and accompanying map). The report includes a reference to a non-breeding pair in the Mack’s Bayou area. This pair does not show up in Tanner’s published counts, either in the monograph or in his dissertation. It seems possible that Tanner concluded the pair that was seen around Mack’s Bayou and the pair with two young that Kuhn found later were one and the same, erring on the side of caution in his final population estimates.

What stands out in both of these documents is the difficulty Tanner and Kuhn faced when trying to find ivorybills other than the John’s Bayou family. This is a topic I’ve touched on in several other posts because of the common belief, fostered by Tanner in later years and advanced by many 21st-century “skeptics”, that ivorybills should be easy to find.

During his brief, two week visit in 1941, Tanner couldn’t get to Greenlea Bend at all and didn’t find the Mack’s Bayou bird, although he found evidence that it was still there. The 1938 report illustrates how hard it was to find ivorybills even more explicitly. Kuhn and Tanner were unable to locate a pair that had been seen by others in a fairly circumscribed area, although it’s possible that Kuhn happened on this pair and the young of the year on June 15th.

Beyond that, it took Tanner and Kuhn “two or three weeks” to find an ivorybill in an area where there was “an abundance of feeding sign”, and Kuhn only found the bird in question by following it to the feeding sign from a known roost. It seems that, while ivorybills may sometimes have been “noisy and conspicuous”, they were for the most part quite the opposite.

Materials are courtesy of the Division of Rare and Manuscript Collections, Cornell University Library.

Screen Shot 2016-05-06 at 7.38.09 AMScreen Shot 2016-05-06 at 7.38.56 AMScreen Shot 2016-05-06 at 7.39.33 AMScreen Shot 2016-05-06 at 7.42.31 AM

 


Two More Rare Ivory-billed Woodpecker Images

These two photographs, taken by Tanner in 1938 and published in his dissertation, have not been otherwise widely disseminated or (to the best of my knowledge) reprinted elsewhere. Each is interesting in its own right, and not just because they add to the small body of indisputable ivorybill imagery; the first shows the behavior of a near-fledgling (Sonny Boy) in the nest and the second for the position of the male’s crest, which is more recurved than in most or all other stills. Another series of rare images is here. Images are Courtesy of the Division of Rare and Manuscript Collections, Cornell University Library. Screen Shot 2016-05-03 at 1.39.32 PMScreen Shot 2016-05-03 at 1.40.39 PM


Rare Ivory-billed Woodpecker Images

 

 

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.

 

 

IMG_1119 (1)

IMG_1130

IMG_1116 (1)

IMG_1120 (1)IMG_1122 (1)


Strips, Flakes, Chips, Chunks, and Slabs: Squirrels, Pileated Woodpeckers, and Ivorybills, Part 4

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.

Ivorybill Scaling Courtesy of the Division of Rare and Manuscript Collections, Cornell University Library

Ivorybill Scaling Courtesy of the Division of Rare and Manuscript Collections, Cornell University Library

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).

DSC01153

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.

SquirrelChips

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:

9”x2.5”

7”x2.25”

5.75”x2″

7.5”x1.75”

4”x1.75”

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.

IMG_0250.JPG

The following are measurements of some fairly typical suspected Pileated strips from a sweet gum:

7”x1”

8”x.8”

7”x.8”

6”x.8”

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.

DSC01477

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).

DSC01396

DSC01190

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.)

Hickory2Chips

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.

Frank adds:

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.

DSC00031The 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.)

DSC01217

DSC00074