More Recordings from March 15: Approximately Three Hours of Kent-like Calls and Analysis

On March 15, Phil Vanbergen and Matt Courtman recorded numerous kent-like calls at the same location where we heard several calls on March 11 and 12. Phil was able to record two of the March 11 calls. That capture is included in the post, along with Phil’s audio from the morning of the 15th. I heard two of the calls on the 11th; the second one in particular struck me as being consistent with the Singer Tract recordings; the first seemed a little low pitched to my ears, an observation that’s captured on the recording. Steve Pagans and I heard several calls on the 12th, but these were not recorded.

Matt obtained nearly three hours of audio, and to my ears the sounds are coming from 2-4 distinct sources; I had the same impression after listening to some of Phil’s clips. I have now listened all the way through Matt’s recordings several times and will share my analysis below. Matt and Phil are likely to weigh in later with their perspectives. I also have a couple of trip reports pending, so there should be a lot of activity on the blog in coming weeks.

To start with, I counted over 200 kent-like calls in all.

On the long clips posted here, I’ve edited out all of Matt’s ADK (anthropogenic double knock) series, which he did on the half hour. The knocks are very loud, as can be heard from the one trailing sound I’ve left in. I also snipped out several minutes of conversation between Phil and Matt. The ADKs seem to have led to more frequent calling and may have provoked some double knocks, something we may address in a future post.

Edited to add: On further review, there does not appear be a correlation between ADKs and more frequent calling. Clips like the one posted below can be deceptive. One kent-like call that overlaps with a knock has been deleted. There is also one possible knock in response. Caution, ADKs have not been completely spliced out, and they are loud. See bottom of page for brief clip and sonogram.*

Between 6:12 and 6:25 on the last long recording made that morning, there are five calls of differing durations and volumes, followed by what may be a double knock. Similarly, at the end of the full clip, starting at 14:14, 3 calls are bracketed by some potentially interesting knocks, 2 before and 1 or 2 after.

The first four clips below are shorter, amplified extracts on which the calls can be heard easily.

The first two of these are extracted from the final segment described above and include the interesting, tooting sounds and possible knocks.

The third clip includes multiple calls over 2 minutes and nine seconds, along with a wide variety of other sounds.

The fourth is four minutes long (pardon the airplane noise) and should provide additional context while also revealing some of the variations among the calls.

For those, like me, who don’t have professional sonogram software, I recommend using Sonic Visualizer – an easy to use, free program that enables you to watch the sonogram as you listen.

And for those who are unfamiliar with avian bioacoustics, this is a great place to start. I’m on a very steep learning curve myself and am prepared to stand corrected about any misstatements in this post.

Many of the sounds are audible on built-in computer speakers, but playback through headphones, earbuds, or external speakers is highly recommended.

 

I think these calls were likely made by Ivory-billed Woodpeckers. My perspective is based in part on the fact that I have spent all or part of nearly 40 days in close proximity to where the calls were recorded, starting in 2014. A considerable amount of this time was spent sitting quietly, and the total person hours spent in the area is well into the hundreds. We have had occasional kent-like calls, possible double knocks, and possible sightings over the years, but nothing approaching what transpired on the 15th.

Matt spent the morning of the 16th in the same location and did not hear any of the sounds, and Patricia and I spent 4 mornings and one afternoon there between the 23rd and 31st and heard no similar calls. I think this militates strongly against the idea that the source of the sounds is a common resident of the area.

Three alternative hypotheses have been suggested.

On the morning of the 15th, Phil proposed that the sounds might be tree squeaks. There appear to be multiple tree squeaks on the recording, some with similar pitches, but they bear little resemblance to the kent-like calls on the sonogram or to the ear. In addition, the calls sometimes come singly, sometimes in groups, and they vary in pitch, volume, and duration and seem to occur independent of wind velocity (on the 11th we noted that there was no wind.)

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Sonogram of first clip, showing apparent tree squeaks before and and immediately after two kent-like calls – the stacked horizontal lines right of center.

The first sound, at just after 4 seconds on the second clip, seems ambiguous. The sonogram is somewhat similar to the kent-like sounds, but the duration is very short, and it has a creaky quality. It’s also associated with the two creaky sounds that follow. These can be heard frequently over the course of the morning, and their appearance on the sonogram is nearly uniform.

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Sonogram of second clip showing tree squeaks.

One reviewer proposed Wild Turkey and Blue Jay as possible sources. I think turkey can be ruled out due to the absence of other turkey-like sounds associated with these very persistent calls.

Blue Jay strikes me as a more plausible alternative. Blue Jays can be heard at numerous times on Matt’s recordings. And Blue Jays are known to make kent-like calls, some of them very similar to known Ivory-billed Woodpecker sounds. This is likely not mimicry, since the most similar recorded calls I know of were obtained in upstate New York. The recordist noted the similarity. On the sonogram, the resemblance between these calls and either known Ivory-billed Woodpecker sounds or Matt’s recording is not as strong as it might seem to the ear. While they share a strong third partial, the Blue Jay fundamental is higher and some of the higher partials are considerably stronger.

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Kent-like, suspected Ivory-billed Woodpecker calls recorded by Matt Courtman on March 15, 2017. Note the relatively strong base frequency and 3rd partial, and weak 2nd, 4th, 5th, and 6ths.

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Kent-like Blue Jay calls. Note the relatively weak fundamental and strong second through fifth partials.

It’s also important to note that on the Cornell Blue Jay recording, the kent-like calls are intermixed with typical Blue Jay vocalizations. Over the three hours of Matt’s recording, kent-like calls occur during periods when Blue Jays are vocalizing and during periods when Blue Jays are silent.

Some of the kent-like calls have harmonics consistent with Cornell’s recorded playbacks of Singer Tract calls at 145 meters. Many are lower in pitch. Most have a considerably longer duration, although to my untrained eye/ear, some seem close to the 80-100 ms duration on the Cornell recording. More on duration below.

On March 28, I did some playback of Singer Tract calls using an iPhone and a bluetooth speaker. Patricia recorded them on a Roland Edirol R09HR digital recorder. I’m including the recording and the sonogram for comparison. Like Matt’s recordings, the second partial is strong throughout, and the 1st, 3rd, and 4th appear to be weaker than for the Blue Jay shown above.

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At various points, Phil also experimented with doing playback, using calls recorded in 2010 at the old Project Coyote site. (He also played back several other species – Red-bellied, Golden-fronted, and, possibly, Gila Woodpecker to gauge Red-bellied response, and Eastern Towhee out of personal interest.) Examples of putative ivorybill playbacks can be heard over the first 3 minutes of the fourth long clip posted above and also during the first part of the fifth. These sounds are longer but similar in tonal quality to the lower pitched calls. Their harmonic structure is different, however, with a fundamental at around 800 hz, a second partial at around 1600, and a fairly strong higher partial at approximately 5000 hz., and should be readily identifiable on the sonogram.

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Higher pitched playback calls, at middle left and far right.

Phil’s playbacks do not seem to have provoked any kent-like replies. Blue Jays can be heard during the same time frame, but it’s not immediately apparent whether the recorded Blue Jay calls are responses or merely contemporaneous vocalizations. This segment includes some Blue Jay vocalizations.

With regard to Blue Jays and the numerous kent like calls heard from March 11, 12, and 15: to reiterate, many hours have been spent in this vicinity, with close attention being paid to kent-like sounds. These are heard infrequently and never before in such quantity or over such an extended period. If Blue Jays in the area were making these sounds, we almost certainly would have heard and recorded many of them over the years. In addition, both Steve Pagans and Matt Courtman are experienced and skilled ear birders and neither thinks these are Blue Jay calls.

It’s also worth pointing out that another potential confusion call can be heard on the recordings – White-breasted Nuthatch. The sound is similar but much weaker, as should be clear from the amplified March 15 excerpt. On the sonogram, just below the amplified recording, the calls show up very faintly, with dominant frequencies of around 2200-2400 hz and a relatively strong partial at 1700-1800.

 

 

I encourage people to listen through and draw their own conclusions. Input from those with expertise is welcome.

While I can’t say if any of these calls are a perfect match for the Allen and Kellogg recordings (some may be), many of them are close on the sonogram and similar to the ear. It’s important to bear in mind that the Singer Tract birds were likely agitated when those recordings were made, even though Tanner described some them as being good examples of kents. It’s also important to read Tanner’s descriptions carefully, though as is so often the case, his writing can be opaque. Perhaps his most important observation was that “all of the notes have the same nasal, trumpet-like quality.”

According to Tanner, “The notes of the nuthatches are the only bird calls I know that sound like the voice of an ivorybill; the Ivory-bill’s calls are much longer and pitched higher than the calls of a White-breasted Nuthatch, are more in the range of a Red-breasted Nuthatch.” (Emphasis added.) By contrast, Hasbrouck, writing in the 1890’s, described it as being “exactly like the note of the White-breasted Nuthatch” only much louder and stronger.

Tanner’s reference to Red-breasted Nuthatches has always confused me. I’m very much in Hasbrouck’s camp; I think the Singer Tract kents sound far more akin to White-breasted than Red-breasted Nuthatch. Either way, most of the Allen and Kellogg kents are lower pitched than typical White-breasted Nuthatch calls, as are the ones on Matt’s recording. In addition, the Allen and Kellogg kents seem to be of similar in duration to typical nuthatch calls, rather than longer or “much longer”. This too suggests that they are not typical but are more rapid and perhaps higher pitched due to agitation. Tanner wrote further, “[t]he kent note, given in monotone or infrequently, is the ordinary call note. When the bird is disturbed, the pitch of the kent rises, and it is repeated more rapidly, frequently doubled, kent-kent, with the second note lower. The prolonged and slurring, kient-kient-kient call I always heard when two or more birds were together.” This call was never recorded.

According to Allen and Kellogg, “kenting varied a great deal” and a male bird called “loudly and deliberately”, again suggesting that many calls were of longer duration than those on the recording. Tanner’s notes also point to this variability. At one point, he wrote of “1 and 2 syllable yaps”; he has the Mack’s Bayou bird (whose voice he claimed he could recognize) making a “kient-kient” and also transliterated calls with “keent keent” and “yeenh yeenh” (Bales). These renderings all suggest a more drawn out call than those on the Allen and Kellogg recordings. George Miksch Sutton described the Singer Tract birds’ calls as, “strange, bleat like, not quite sharp enough for a woodpecker’s cry. It was slightly nasal in quality and it sounded to me like ‘Gip!’, with a hard g“. Sutton’s description also suggests that many kents had a fairly long duration.

Edited to add: similarly, several observers (Audubon, Beyer, Hoyt)  described ivorybill calls as “plaintive”; this too seems to imply calls of longer duration than what’s heard on the Singer Tract recordings.

Given the resemblance to the Singer Tract recordings and the lack of plausible alternatives, I posit that these calls are at worst highly suggestive of Ivory-billed Woodpecker.

*Possible knock and kent-like calls temporally associated with ADK series. Caution remnant ADKs are loud.

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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.

 

 

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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).

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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.

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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.

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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).

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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.)

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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.)

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Trip Report, Part One: March 31-April 5, 2015

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. OldHickory3 oldhickory2

Extensive scaling on an older hickory snag. Work goes from near the base to near the top. Atypically, some of the work at the base appears to be more recent than the rest.

Extensive scaling on an older hickory snag. Work goes from near the base to near the top. Atypically, some of the work at the base appears to be more recent than the rest. While the work is not fresh, and the bark has started to loosen, it is still within the decay stage described by Tanner as being preferred by ivorybills, as shown by the presence of twigs.

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. SweetGum1 SweetGum2 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. IMG_0888 DSC00076 DSC00070 DSC00074 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.

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Close-up of 2" diameter limb that apparently broke off while being fed upon

Close-up of 2″ diameter limb that apparently broke off while being fed upon

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. Top of Snag LittleSapling ExitTunnelExpanded IMG_0876_2 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.


Rapid Evolution – I Think Not: More on Game Cams and Challenges

Cyberthrush’s blog has been an important resource for people with an interest in the IBWO for nearly a decade. I’ve agreed with him at times and have taken strong issue with him at others. His latest post falls into the latter category and strikes me as being somewhat irresponsible; it’s worthy of submission to The Annals of Armchair Quarterbacking. I responded in the comments but have some additional observations that seem better suited to posting here.

The inspiration for Cyberthrush’s post is an image someone sent him of suspected bark scaling low on a tree. The image is not shown in the post, but I suspect I’ve seen it and, if so, am sure it was the work of a mammal. In any case, he hypothesizes that the IBWO has rapidly evolved to live almost exclusively in the canopy. He uses the specialization of certain species – seabirds, Chimney Swifts, and warblers – to draw parallels, ignoring entirely that none of these species evolved nearly so rapidly. The only basis for this theory is the failure to obtain clear photographs.

He digresses to dismiss virtually all the photographs of feeding sign, cavities, and putative IBWOs and virtually every recording of putative kents or DKs he’s seen over the past 9 years. He writes: “I don’t want to discourage people from sending such things along, but I do want folks to know that the chance of getting a positive response from me is extremely slim . . .”

He goes on:

“I’m in the camp that believes any remaining IBWOs have evolved heightened wariness and caution, and as such DO NOT spend ANY extensive time at ground level, where they would be far more vulnerable. In fact, I believe they are now almost exclusively residents of the upper canopies, other than when flying from point A to point B and requiring a clear pathway. While they might land momentarily lower on a tree, they probably spend most of their daily lives minimally 35+ ft. high up (maybe 50+ ft.) on tree trunks/branches and inside cavities, well above levels frequented by Pileateds and other woodpecker cousins (and generally out of easy sight-line for searchers). It’s not clear to me how many of the remote automatic camera traps were ever set that high (though it’s clear several were not). Like Swifts in the air and Albatrosses at sea, I think Ivory-bills may spend most of their lives solely in the canopies… if you send me a photo of foraging sign or a cavity or a fuzzy bird lower than ~35 ft. high, I probably won’t take it too seriously (even though there are historical records of such cases), unless there are overriding additional details to catch my attention. If Ivory-bills currently lived and foraged below 35 ft. to any significant extent I believe we’d have the definitive evidence we need by now (well before now!); only perhaps as a denizen of the upper reaches might they be able to carry on successfully, while also evading encounters and detection to the degree they have . . .”

I don’t know who else is in his camp. Some have certainly argued that hunting pressure led the IBWO to become hyper-wary, and I can accept that hypothesis to some degree, although I think scarcity and the nature of the habitat have far more to do with the lack of conclusive documentation. The suggestion that the species evolved to exist almost exclusively in the canopy, when it was not infrequently seen feeding near the ground, is nowhere near as plausible, and it’s invented out of whole cloth.

As I wrote in the comments:

Your exclusion of any work below 35′ is arbitrary and wrongheaded, IMO. Forget Allen and Kellogg, Tanner even observed that they’re “not averse” to coming near the ground. Do you really think such a significant behavioral change evolved post-Tanner? An animal seeking food is going to go where the food is, and as it happens, the largest quantity of food is often to be found in the boles. I agree that cavities will be high up and also that work that’s exclusively near the base of the tree is suspect, but when the work goes higher than about 10 feet you can pretty well rule out a mammalian source (unless giraffes are around or there’s some heretofore undiscovered porcupine species in the swamps of Louisiana and Florida). When it’s very extensive, you can be pretty confident that it’s either PIWO or IBWO, and as I’ve argued at length on the Project Coyote blog, I think there is a limited range of work that is identifiable as IBWO.

This really is giraffe foraging sign, photographed in Louisiana . . . Long story.

This really is giraffe foraging sign, photographed in Louisiana . . . Long story.

One avian example of rapid evolution (though not nearly so rapid as Cyberthrush’s IBWO) is the Cahow, but that adaptation involved a change in nesting behavior due to a lack of adequate sites, something that’s far more akin to the kinds of survival strategies discussed in this recent post. There’s simply no reason to think that IBWOs could have suddenly evolved to live almost solely in the canopy. Not when Allen and Kellogg even observed one feeding on the ground; not when Kuhn observed one feeding a foot up; not when one of the clearest photos of bark scaling shows the work going to the base of the tree (the bark chips in this image are worth a close look, and they resemble many that we have found.)

With regard to aiming cameras at the canopy, I discussed the limitations of game cam technology in this post. The challenges increase dramatically when the cameras are aimed even higher, as is illustrated in this photo of a bird about 75’ up in a tree. There’s simply no way to get a conclusive ID. I think it’s suggestive of a female IBWO and that red would be visible in the crest if it were a PIWO, although it’s clearly nowhere near as intriguing as our other two Reconyx photos. Frank disagrees and thinks it could be anything.

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Reconyx image and detail. Old Project Coyote search area, March 2009

Reconyx image and detail. Old Project Coyote search area, March 2010

Either way, aiming these very poor resolution, short focal length cameras high complicates matters exponentially. The likelihood of getting a clear image at such a great distance and with backlighting is infinitesimal. Aiming high is likely to be a wasted effort. One final note about game cameras, Cyberthrush attaches a great deal more significance to the lack of photos than I do. As far as I’m aware game cameras were only extensively deployed in Arkansas, South Florida, and the Choctawhatchee. They’ll only work if they’re deployed at the right time and in the right place, something that’s much easier said than done. As I’ve mentioned previously, virtually all the scaling we’ve found seems to have been done in a very limited number of visits to the tree, perhaps just one, and in the very rare instances where we’ve found evidence of a return of whatever removed the bark, there has been a gap of several months between visits.

The key to all of this is going to be finding a roost or nest site (unless someone gets extremely lucky.) I’m convinced that feeding sign is what can point searchers in that direction; it’s what led Kuhn and the Allen and Kellogg expedition to birds in the 1930s. That’s the reason for my focus on it. Cyberthrush does a disservice to all searchers by suggesting, based on unfounded speculation, that virtually anything found below 35’ feet is not worthy of attention.

Heavily scaled young oak with suspected IBWO work extending from the base to well up on the trunk.

Heavily scaled young sweet gum or oak with suspected IBWO work extending from the base to well up on the trunk. Note the large bark chips at the base.


IBWO Minutiae for the Holidays

In searching Cornell University’s online digital archives, I ran across some IBWO related photographs from the 1935 Allen/Kellogg/Tanner expedition in the Albert Rich Brand collection. Many of these pictures are familiar and have been widely published. Others are likely to be new, even to the most obsessive researchers, since Brand was a relatively less celebrated member of the expedition. One of the more interesting images shows a nest cavity near the top of a very long dead pin oak. This appears to be one of the two nest trees found by Allen and Kellogg and listed and discussed by Tanner, pp. 67-70. The typewritten caption on the photograph reads “The third Ivorybill’s nest. . .”, although Tanner only mentions two. The quality of the photograph is poor, but it is interesting because the stub is clearly long dead.

For my purposes, the most interesting photograph, titled Rock Elm Observation Blind shows the better known nest tree (a maple) from a different perspective than the published photos and includes more of the trunk than the others I’ve seen. I downloaded the image, and enlarged it as best I could. Readers can do the same. On close examination, a bill is visible protruding from nest cavity, making this a modest addition to the body of ivorybill photographs. What I find most significant is the appearance of the scaling on the bole. While the condition of the underlying wood seems to be considerably worse than what we are deeming to be grade A scaling, the similarity in appearance is dramatic, especially on the edges. The resemblance between this work and the scaling found in July in the northern sector is particularly striking.

Edited to add: All the digitized Brand collection images are here. They’re worth a look.

In addition, I’ve found a hand tinted version of “Rock Elm Observation Blind” in the Arthur A. Allen collection, under the title “Ivory-billed Woodpecker – Blind at Nest“. Although the colors are slightly washed out and smeared, the bird in the cavity is a little easier to see, and the similarities between the scaling on that tree and the scaling we’re finding are a little more evident, at least to my eyes.

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Wishing everyone the best for the holidays and the coming year!