Another Pileated Scaling Sequence – January 11, 2017

Part 1 is here. Part 2 is here. I encourage you to read those posts first, as this one only adds a little to what’s been documented and discussed. Phil Vanbergen found an additional sequence this morning, one that shows the balance of the scaling that was done on the limb between December 22nd and January 26th.

In this sequence, Pileateds do most or all of the work that I had ascribed to squirrels. As in the other two sequences, the birds spent approximately fifteen minutes foraging, removing a couple of small patches from the lower part of the limb before working somewhat more extensively on the upper left. As in the other sequences, it appears that one bird did the vast majority of the work, but I haven’t found any frames that are well enough resolved to determine whether it was the female or the male. Per Phil, squirrels can be seen in additional sequences, “often poking around the scaled patches”.

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Pileated Woodpecker Scaling on the Limb of a Downed Sweet Gum – Part 2

Thanks again to all who sent condolences, and appreciations of Frank Wiley and our work. Your sympathy and support have comforted and encouraged me during this difficult time.

Part 1 is here. This post supplements the analysis at: Feeding Sign: Some Possible Ivorybill Diagnostics. I’ll be reiterating ideas that are familiar to longtime readers; I have posted many of the photographs before; but there’s some additional research and some new perspectives informed by the Pileated scaling sequences obtained in December and January.

I am now firmly convinced that the work we’ve found on a small number of hickories over the past several years cannot have been done by Pileated Woodpeckers. I have believed this to be the case for some time, but the recent sequences showing how Pileateds scale sweet gum bark provide strong, direct evidence in support of that conviction.

As noted in Part 1, sweet gum bark is in the mid-range for tightness among hardwood species. Hickory bark in general, and bitternut hickory bark in particular, is at the highest end of the range in terms of adhesion. Hickories belong to the genus Carya, which is divided into two types, “true” and “pecan” hickories. Bitternuts are in the pecan group, “which are not equal to true hickories in strength, hardness, and toughness.” This inequality is relative, and the differences are modest. In addition, the timber industry identifies bitternuts and a true hickory species, mockernuts, as “tight barked” hickories. True hickory bark adheres so tightly that its removal poses problems for the pulp lumber industry, and I suspect that for the purposes of the linked study, bitternuts are treated as true hickories. In any case, it is safe to say that hickories are the tightest barked hardwood species in our search area, and I have observed that hickory bark can remain tight for years after death, given the right conditions.

Now let’s examine the physical evidence we’ve found with regard to both sweet gums and hickories.

These are three of the largest chips found under the medium-sized limb of the downed sweet gum. There was one larger chip that broke on handling, as well as quite a few smaller ones. This is known Pileated Woodpecker work.

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It is perhaps more accurate to describe these as strips. They’re approximately .25″ thick and 2″ across at the widest points.

Now let’s look at some presumed Pileated Woodpecker work from another sweet gum that appears to have been longer dead. This work is from somewhat larger limbs and a nearby hanging broken limb. I can see indications, patchiness and layered appearance, that would lead me to suspect Pileated, just based on the field impression. The chips are even more revealing, even though some of them are larger than what I would have expected.

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Here’s an image of the chips found on the ground. There’s been a lot of scaling on this tree, and some older chips (that could be consistent with ivorybill) can be seen in the photograph. Note the variability in size.

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Here are some of the fresh chips I collected, shown with my 13″ MacBook Air for scale.

img_1260Again, some of these chips are slightly larger than I would have hypothesized for Pileated Woodpecker, but the appearance, which suggests that a considerable amount of pecking was required before the bark was removed, would have led me to assume Pileated. I’m confident this is not squirrel work either, based on the exit tunnels and the way they’ve been pecked at (most readily visible at the far right). Note also that these chips were so brittle that the larger ones broke in transit. This work was done on larger limbs, and the bark is approximately .375″ thick.imgp4295

By contrast, the hickory scaling is on boles, where bark is tighter and thicker; the surface area involved is typically much greater; and there is no sign of the layered appearance, which I presume to be a consequence of pecking rather than chiseling/prying. In those instances in which we’ve found fresh work, most or all of it appears to have been done within a very short timeframe. The example below, the homepage tree, was still alive, with the scaled areas wet with sap when found.

We found this tree in the spring of 2013 and monitored it regularly for over a year. There were no return visits by whatever did the scaling, and the only other woodpecker work involved the removal small patches of bark by a Hairy Woodpecker (captured on a trail cam). This particular tree had been partially uprooted and was in a lower, wetter area than many of the other hickories that have been worked on in this manner. By the spring of 2016, it had fallen and Pileated Woodpeckers were feeding on the rotting log.

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I’ll repost the known PIWO scaling, done over approximately 30 minutes in two visits, five weeks apart, for comparison. Even if the same species of tree were involved I’d have suspected two different sources for the scaling.

As I see it, our Pileated sequences show that it would have required hours for a PIWO to have scaled so extensively on the hickory bole and suggest that they could not have done so as cleanly. The chips (>.375″ thick on a relatively young tree, not at all brittle, and no hint of pecking or removal in layers) and the remaining adhering bark should have a very different appearance if Pileateds were responsible, especially given the substantial differences between sweet gum and hickory bark adhesion and hardness. The work we’ve found on hickories involves both live and recently dead examples. Again, I’ll repost an image of the hickory chips from this tree for reference.

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Suspected Ivorybill Chips

As discussed previously, the hickory scaling also has a distinctive appearance that strongly resembles presumed Ivory-billed Woodpecker scaling on one of the Singer Tract nest trees, a maple.

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Suspected Ivorybill Scaling on Hickory 2013

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Detail of the “Elm Rock” Nest Tree, 1935, courtesy of the Division of Rare and Manuscript Collections, Cornell University

I think it may be possible to distinguish Pileated and Ivory-billed Woodpecker work on sweet gum branches, based on very close examination of the scaling and the bark chips (when possible). The effort to do so is complicated by the fact that both Pileated Woodpeckers and squirrels can and do strip bark in similar ways. Extensive, mostly contiguous, and clean appearing scaling on larger limbs may be suggestive for ivorybill, as in the example below and as Tanner suggests, but even if ivorybills are doing some of this work, identifying it requires making some fine distinctions.

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By contrast, I think the work on hickory boles in our search area is diagnostic for ivorybill. Our focus going forward will be on trying to anticipate and document whatever is scaling bark from the hickories in this distinctive manner. Given the nature of hickory bark, I suspect I will have reached a dead end if it turns out I’m wrong about this.

One final note, identifying potential target trees is a very long shot. We found no scaled hickories of this type in 2015-2016. I have been looking for candidates on the last two trips and have found two wounded trees, both within 50 yards of hickories that have been scaled in recent years.

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We’ll be targeting these and will be looking for two more when I return in March.


Pileated Woodpecker Scaling on the Limb of a Downed Sweet Gum – Part 1

I’m still in mourning and adjusting to the loss of my friend. Thanks to all who have expressed appreciation for our work and a desire for it to continue. I’m sure Frank would have felt the same, and with that in mind, this will be the first of two or three installments discussing Pileated Woodpecker work on sweet gums that we’ve recently documented.

After my December trip, Phil Vanbergen and John Williams retrieved the trail cam we had deployed on December 21. They took the camera to Frank’s house, reviewed the card, and found that two Pileateds had visited the downed tree on the 22nd and had scaled some bark near the base of a medium to large limb. Phil, who has spent time with me in the field and who has paid close attention to my approach to analyzing feeding sign, immediately suspected Pileated for this work, based on the appearance of the scaling and the characteristics of the bark chips.

Rather than extract the images at that time, Frank and Phil opted to redeploy the camera. Although I had not yet seen the frames, many of my last communications with Frank, both on the phone and via email, touched on this subject. He was tickled by the fact that we’d anticipated and documented scaling activity on an untouched limb and was eager to get back out and see for himself. Sadly, that was not to be.

Phil and I retrieved the trail camera on January 28. I had visited the site on the 26th and had noted some additional scaling consistent with what I’d expect for Pileated Woodpecker, although with some bark chips on the larger side. As it happened, the second round of scaling had taken place approximately three hours earlier, five weeks to the day after the first.

In both instances, it appears that almost all the scaling was done by a female, although the image quality is too poor for me to be 100% certain. In both cases, the bird spent approximately 15 minutes on the trunk. It seems that squirrels (seen briefly at the beginning of the January series) are responsible for the modest quantity of scaling on the upper, less vertically oriented, part of the limb; this was my instinct at the time, and the idea is supported by the footage. The full time lapse sequences are at the bottom of the page. Phil extracted both sequences, and Steve Pagans created a slower version of the January 26th clip. The first four photos in the tiled mosaic series below were taken by Phil Vanbergen.

I’ll go into more detail in subsequent posts, but for now, I have a few observations.

  1. This work has a distinctive appearance, what I’ve called a layered look to the edges, that is consistent with what I’ve previously hypothesized for Pileated.
  2. While some of the bark chips are on the large side for what I have ascribed to Pileated, none are anywhere near as large as the larger ones that that we’ve ascribed to ivorybill. In addition, the chips found at this location and at another where I suspect the source is PIWO, seem to be less uniformly large in size and sometimes show signs of being taken off in layers, which matches what’s visible on the limbs.
  3. The tree in question was no more than six months dead, and the bark at the edges of the scaled area remained tight; however, dormant sweet gum bark is in the midrange of tightness relative to other hardwood species.
  4. This is a decay class that Tanner associated with ivorybills not PIWOs, but it’s clear that Pileateds can and do scale very recently dead sweet gum limbs, at least in mature bottomland forests.
  5. Tanner’s photographs provide little guidance in terms of differentiating between Pileated and Ivory-billed Woodpecker work on high branches. I suspect he thought of his monograph as more epitaph than guide to identifying feeding sign. Nevertheless, his descriptions offer some clues. “Scaling, the Ivory-bill works steadily, removing all the bark for quite an area; one may work at a spot for an hour or more.” And for Pileateds, “What scaling Pileateds were observed to do was mostly on loose bark and was never as extensive or as cleanly done as the work of the ivorybills.

To conclude this installment, we already suspected that Pileateds can and do scale freshly dead sweet gums before the bark has loosened; these images show them doing it in a way that is inefficient and neither ‘extensive’ nor ‘clean’. The total surface area scaled over approximately 30 minutes is modest compared to scaling we suspect to have been done by ivorybills. In addition, PIWO work has some characteristics that may be recognizable upon close examination of the affected limbs and bark chips. The fact that these characteristics can be seen on medium-sized sweet gum limbs, with their relatively thin and only moderately tight bark, suggests that it should be even more evident on larger limbs, boles, and other tighter barked species. More on this and on bark chips in subsequent posts.

 

 


Frank Wiley Hospitalized

Two weeks ago, Frank went into the hospital. About two days after admission, he was taken to the ICU with a systemic infection. He started showing signs of improvement on Monday this week and was able to go off the ventilator as of yesterday. (I was there from Tuesday 1/24-Tuesday 1/31.) I know Frank to be a fighter, but even so, he’s doing far better than I expected. His family is asking for prayers, so if that’s something you do, it would be appreciated. My thoughts are with him and with them.

 

 


Trip Report December 16-21, 2016, Part 2

Part 1 of this report is here.

Patricia opted to take the day off on the 19th, so I went out on my own and covered a lot of territory. I had been thinking hard about the hickories and the fact that, in virtually all cases, we’ve seen indications that bark is removed from these trees and stubs within a very brief period or perhaps in a single visit and that other woodpeckers don’t seem to begin working heavily on these trees for extended periods, sometimes for years. Except for changes in color due to exposure to the elements, some of the scaled surfaces we associate with Ivory-billed Woodpeckers can retain their distinctive appearance for at least three years and more likely five or more.

Steve Pagans later explained that this is due in large part to hardening by compression; hickory wood is hard and dense to begin with, and when a tree or stub is leaning, the wood that’s absorbing more weight becomes even denser, harder, and more impervious to rot. Thus, on many of these trees, Pileated Woodpeckers will have worked on the rotting side, sometimes extensively, while the compressed side remains very hard and virtually untouched by woodpeckers.

I examined and marked as many of these trees as I could over the remainder of the trip. Unfortunately, we did not find any of this scaling in the 2015-2016 season. Trying to find more of it this year and trying to find a way to identify potential target trees before they’re scaled will be priorities for me.

I plan to write about this work on hickories and what I think it suggests in an upcoming post. For now, suffice it to say that these particular snags and stubs are a kind of twofer having the decayed substrate that’s preferred by Pileateds and and the hard wood that, following Tanner, is preferred or used exclusively by ivorybills. As noted elsewhere, some bark on these snags and stubs can remain tight for years, and on one of the trees I examined, it was still difficult to remove, even when it had reached a point at which some of it would crumble to powder when it was being pulled off. More importantly, the harder surfaces show modest expansion of exit tunnels and targeted digging work that appear to be associated with the initial scaling (as in the hickory on the homepage and the one in Steve’s photo at the end of this post, both of which were very freshly scaled and alive when found) and little or no other work for a period of years, even when there are signs of infestation by multiple insect species (based on the presence of exit tunnels that vary greatly in size and shape). I’ve included multiple examples, long shots and details, to illustrate.

On the 20th, Patricia, Steve, Phil, and I went to Sector 2 together. We went through the area where I recorded calls in 2013 and where we found concentrations of scaling in spring 2012 and during the 2012-13 season. There has been none since in this little patch. We found no recent looking bark scaling in the morning (as it turned out, we missed a group of three sweet gums with high branch work perhaps a quarter mile to the northeast of this area, see below.) One odd highlight was coming across a patch of forest floor with many of these beautiful ice formations that had formed around the stems of a couple of species of plant.

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At a little before noon, Steve opted to turn back; we had already covered 2.3 miles. Before we went our separate ways, we all speculated on and were baffled as to what might have damaged this sweet gum. The wounds seem to have been caused by a scrape, but there were no downed trees or tops anywhere in the immediate vicinity.

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Phil, Patricia, and I proceeded another half mile farther north, reaching a hickory stub that I found in the spring of 2013, shown below. The stub was still standing, and the areas with putative ivorybill work had lost more bark but showed no signs of further woodpecker activity. The presence of a click beetle in this 2013 photo suggests that parts of the tree were already starting to rot even then.

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We found two sweet gums with extensive scaling on large branches within 30 yards of this snag. Some of the work was recent. This is something that we’re finding repeatedly; even within clusters, the interesting feeding sign often seems to appear in tighter groupings involving two or more trees. I’ll provide a possible explanation in my next post.

We found a particularly unusual bark chip at the base of the tree on the left. While it comes from a relatively small branch, the way it was removed may be significant. Over 1/3 of the chip is cylindrical encompassing almost the entire circumference of the limb; it was not pecked off piece by piece; instead, it appears to have been loosened by several blows and then pried free. The bark is hard, suggesting it was tightly attached; it was moist and contained a good deal of frass when found. The piece is very large, approximately 13″ long and nearly 7″ in circumference.

On the return trip, we found a small group of three sweet gum snags, somewhat on the longer dead side. All three had recent to fresh scaling, and there were very large bark slabs at the bases of two of them. These slabs of bark were dense and hard, suggesting that they were tightly adhering when stripped.

We came across a massive relict cypress on the way back. It’s not the first time I’ve seen this tree, but it never fails to take my breath away.

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~7′ DBH cypress. Dec. 2016. Photo by Phil Vanbergen

On the morning of December 21st, Phil and I went to Sector 1, and Patricia and Steve went to Sector 3. We decided not to deploy a camera on the downed top we had found on the 16th. We have two functioning cameras at the moment, and it seemed more prudent to deploy them on untouched substrates. We didn’t find any new scaling or a substitute target, so we decided to head for Sector 3 where I had a couple of targets in mind.

As we were walking to the car, I got a text from Patricia saying that she and Steve had just had a possible auditory encounter. Steve is a dedicated birder with very good hearing and excellent ear-birding skills. Patricia has limited experience, but she is a retired opera singer with a good general ear. Here are their descriptions of the morning’s events.

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Steve: At about 9:10 am, Patricia and I were in the bottomland hardwood area in Sector 3. The weather was overcast and cold without any wind – very good conditions to hear bird calls. We had walked southward for about a quarter of a mile in the bottomland area when we had decided to do some DKs. Actually it was Patricia’s idea to do some DKs, and we proceeded to find a small American Holly that was the right size to cut two sticks for knocking.

Patricia: I thought it would be a good location, as I remembered Frank, Steve, Mark and I had done them at the same location a few years back. I remember the fallen tree we all sat on for lunch. Steve had sardines! And where Frank sat down at the base of a tree and started to snore. When I mentioned to Mark that Frank was sleeping, Frank retorted “I’m not asleep”

Steve: The location is one where we could see for a distance fairly well. When we started the DKs, we did not keep up with how many were done or how long we did them, but I think it was for about 10 minutes. We made an effort to keep watch for an incoming IBWO that would be responding to the DKs, but we were probably not as diligent as we could have been. At a point we had engaged in some conversation. I was sitting on a sweetgum log and Patricia standing about six feet away. My right side was facing south. Patricia was talking when all of a sudden I heard what sounded like at least two distinct calls from my right. The calls sounded like textbook calls of the IBWO – a bit like a toy horn was being blown. I know White-breasted and Red-breasted Nuthatch calls very well and what I heard did not sound like either of those birds. I immediately put up my left hand to stop Patricia from talking and pointed with my right hand toward the south. I told her what I had heard while we both strained to hear any more calls. There were no more calls. Also, we did not see the bird. It is highly likely that we did not spend enough time watching and listening for the bird after I had heard it call. It is hard to say how close the bird might have been to our location because I don’t know how far their call can be heard.

Patricia: I think I did about 10 DKs, perhaps 15-30 seconds apart. When I didn’t hear anything interesting,I joined Steve, who was about 20 yards away. We started talking, and I was responding to something he said when his hands went up and his eyes widened. He whispered, “Did you hear that? Kent calls?” I shook my head no. We listened for a while, but probably no longer than 5 minutes.

Steve suggested we do another round of DKs to see if we could call in whatever made the sound again. I asked him to do the next round, as I my hands were stinging and sore; plus I wanted to hear them from someone with more experience. I think that, should someone have an auditory encounter, another person should take their place during a second round of DKs.

I stayed where I was standing when Steve heard the kents but was facing directly south. After 3 or 4 DKs, I heard something similar in cadence, but it had a sharper, crisper quality to it (similar to recorded Campephilus double knocks). It came roughly from the southwest. By the time Steve joined me later, I had convinced myself that it was caused by the logging that we heard going on in the distance, also to the southwest. If I mentioned hearing the DK to Steve, I probably downplayed it, blaming the logging or a falling limb; the winds were very calm at the time, and I didn’t hear any similar sounds from the logging that morning.

I have not spent much time in the field and am reluctant to place too much weight on my observations. I’d much prefer the IBWO (should it be out there) land on my shoulder “Sonny Boy” style and leave behind a fine DNA sample, after I manage to take a series of selfies!

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Don’t we all . . . or at least that we could call them in like Barred Owls.

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Barred Owl, iPhone photo by Patricia Johnson

We met up with Patricia and Steve, and Phil set up the cams; one is currently aimed at a sweet gum stub we targeted last year before losing a camera to flooding. There is some fresh woodpecker work, I suspect Hairy, on the stub, so this may be a good  time to target it. The other cam is trained on both a downed sweet gum top and a longer dead snag. Both are within the area where we’ve had multiple possible encounters recently, not far from the heavy concentration of sign found last spring.

Toward the end of the day, Phil went to do an evening stakeout in sector 1; Patricia went with him, while I took Steve a little farther north to show him a couple of the hickory stubs. In this location as well, there were a couple of recently scaled sweet gums in within 20-30 yards of the older hickories, which were similarly about 20-30 yards apart. We also examined one of the hickories Steve photographed in 2013; it was alive at the time. This one had decayed somewhat more rapidly than many of the others I’ve found, but it’s at a lower elevation relative to the nearest water body.

Steve remarked that he’s never seen feeding sign like this anywhere else, and he has spent countless professional hours in bottomland hardwood forests.

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Scaled hickory, 2013. Photo by Steve Pagans.

Frank, Phil, and John Williams will be in the search area over the next few days, so there may be another report coming soon, in addition to the post I’m planning on hickories and foraging behavior.


Trip Report December 16-21, 2016, Part 1

On this trip, I was joined by Patricia Johnson (my wife) who was making her first visit to our search area in over two years. Phil Vanbergen was along on Friday, when a classmate of his, Jeremy Irion, spent also spent the day with us. Steve Pagans, retired forester at D’Arbonne National Wildlife Refuge, was very active in our efforts until he was sidelined with back trouble. He too made his first visit in over two years on Tuesday and Wednesday. It’s great to have Steve along for his birding skills and knowledge of this habitat type. Phil returned on Tuesday and Wednesday, and spent Thursday in the woods on his own. Frank Wiley was unable to get out this time around.

Prior to our departure, rain was predicted for three of our planned field days, but as it turned out, the weather was generally tolerable, if cold at times; Saturday was the only day when conditions, high winds and predicted thunderstorms, kept us away. Patricia and I took that day as an opportunity to visit Tensas National Wildlife Refuge (on the site of the Singer Tract) and Bayou Cocodrie National Wildlife Refuge. More on these visits below.

Although I didn’t have any possible encounters (Steve and Patricia’s will be discussed in Part 2), the trip was an incredibly productive one for me. We found a good deal of recent feeding sign. I also took the opportunity to look at over 10 hickories that have been scaled within the last several years. This is the type of work I think is most compelling for ivorybill.

I got what I think are some important new insights and some ideas about how whatever is stripping bark is behaving over time; these merit a separate post that will likely follow Part 2 of the trip report; I also anticipate writing an addendum to the feeding sign page I added recently. I hope these insights can inform our strategies going forward. It’s especially helpful to get fresh perspectives, so I’m grateful to Phil, Steve, and Patricia. Each in their own way helped me think a little more deeply about my observations; a conversation I had with Frank after a long day in the field was similarly helpful.

The groups of images in this post are in “tiled mosaic” format. Clicking on any single image will enable you to scroll through the group and enlarge the individual photographs if you choose to.

We met Phil on the edge of what we call Sector 1 at 6:45 am on the 16th. The weather was cloudy, cold, and windy; later in the day, the thermometer soared to nearly seventy, but the skies remained a wintry gray, less than ideal conditions for finding feeding sign or observing birds. Nevertheless we did find some recent work on both standing and downed sweetgums and on a broken hickory limb, all of this in an area where we’ve found an abundance of scaling every search season. None of this work is in the category I find most compelling; the hickory limb is probably most interesting due to the characteristics of hickory bark and the very large bark chip we found below the limb. Given what we’ve observed on hickory boles, this may be good target tree for later in the season.

The scaling on the downed limb has some features that might point toward Pileated, especially the layered appearance at the lower right and the patchiness of the work on the smaller limb. Conversely, the shredding of the cambium on the stub is consistent with what Edith Kuhn Whitehead told us her father associated with ivorybills.

Phil and I considered aiming a trail cam at the downed limbs but decided the work was not quite interesting enough.

The weather forecast for the 17th was ominous, with winds upwards of 20 mph and thunderstorms predicted for the afternoon. Patricia and I thought we might be able to spend a couple of hours in Sector 1, but when we reached the trailhead we found a truck parked where we were planning to walk in. Given the bad weather and the presence of hunters, we decided to head straight for Tensas, a pilgrimage I’d been wanting to make for some time.

The drive took a couple of hours, and our Wayz app sent us on a couple of roads that dead-ended in bean fields, but we finally made it, only to find the visitor center closed for the weekend.

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We took a walk on the boardwalk behind the headquarters and found a dead tree that had been almost completely stripped of bark, large soft slabs of which were lying around the base. I’m posting a photograph to illustrate how difficult it can be to explain what we’re finding to those who haven’t seen it firsthand. I doubt there are ivorybills in Tensas, but if I found this work in our area, I wouldn’t suspect ivorybill. The remaining adhering bark is loose and decaying; the large slabs we found on the ground were soft and pliable. The tree in the background has a little bit of scaling on it too, but it is in an advanced state of decay, and the bark has not been removed from large, contiguous areas.

As we drove around Tensas, we did note occasional instances of high branch scaling, but nothing remotely suggestive. Again I’m again including these examples in hopes of providing more clarity with regard to the kinds of feeding sign I find suggestive for ivorybill; this work doesn’t qualify; it is on very small, longer dead limbs; it does not involve large, contiguous areas; nor does it reach the bole or larger parts of the limbs.

We spent a couple of hours exploring the refuge from the road, stopping at Africa Lake, on the West side of the Tensas River, and then drove Sharkey Road, stopping for a somber moment on the bridge over John’s Bayou. I’m facing south in the picture below; Tanner would have walked north to the core of the home range. There are strips of maturing woods along the banks of the bayou but bean fields to the east and west. Tensas is big, extensively wooded, and an impressive restoration effort is under way, but the visit left me saddened, with a more visceral sense of what was lost when the Singer Tract was logged.

From Tensas, we went to Bayou Cocodrie, a nearly 15,000 acre refuge that’s part of a large, east-central Louisiana potential habitat complex. While the corridors are not uninterrupted, they encompass many thousands of acres of maturing forest, from D’Arbonne and Tensas National Wildlife Refuges to Raccourci Island and Tunica Hills. There’s some connectivity with the Atchafalaya Basin as well. Bayou Cocodrie is fairly isolated and hard to reach (Wayz was unhelpful again); it includes a small (775 acre) stand of old growth hardwoods (the Fisher Tract), and there may be a good deal more surrounding forest that’s suitable for ivorybills. I met a professional hunting guide a couple of years ago, and he claimed to have had an encounter there. We’re planning to visit Bayou Cocodrie and see the Fisher Tract and surrounding areas on my next visit.

Patricia and I were on our own on the 18th, which was a much colder, clearer day after some early morning clouds broke up. We spent the early part of the day in the northeastern part of Sector 1 and didn’t find anything of interest. We went to the scaling concentration in Sector 3 in the latter part of the morning and stayed in the area until about 3 pm.

I didn’t notice any new scaling worth mentioning, but we found a limb that had fallen and broken apart in the storms that had raged through the night before. The scaling had been done before the branch fell, and except for one targeted dig, there was no associated excavation. While some of the bark had loosened, it was tight (impossible to remove without an implement) on the edges. I’ve included several images because they help illustrate the difference between the very extensive scaling we’re finding in our area and what’s common elsewhere (as shown in some of the Tensas photos). Patricia is 5’9″.

Stay tuned for Part 2.


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.