March Recordings Revisited: A Compilation of the Calls for Easier Listening, Interesting Knocks, and Some Additional AnalysisPosted: December 10, 2017
If you’re interested in possible double knocks, I’ve made what may be some important new finds, so be sure to read the whole post and listen to the clips at the end.
In the meantime, I think this post will be of interest to many readers – from the new ones who’ve found the blog either because of the recent sighting or after reading about Project Coyote on the LABird list (thanks to Jay Huner for the mention) to other ivorybill searchers and aficionados to those who have had trouble hearing the putative ivorybill calls on the March recordings or didn’t want to wade through all the audio.
In the easy listening department, Steve Pagans has made a compilation of the clearest calls on Matt Courtman’s first, 2 hour clip recorded on the morning of March 15 using NCH software.
I tweaked Steve’s version a bit, amplifying it and applying noise reduction using Audacity, an equivalent program. Sonograms were generated using Sonic Visualizer, to my knowledge the best free program of its kind.
Both Steve’s version and mine (immediately below Steve’s) should make it considerably easier to hear many of the calls recorded that morning. Steve’s is somewhat cleaner, and mine is somewhat louder.
Steve’s extracts from Matt’s first clip:
With additional amplification:
Steve has done similar, shorter condensations of the the other two recordings Matt made. (The extract from the second clip adds little, so I’ve opted not to post it.)
Steve’s extract from Matt’s third clip:
With additional amplification:
The calls have a very consistent sonogram pattern (the stacks of three or more parallel horizontal lines), with an emphasis on the second partial (third horizontal line from the bottom). There are apparent tree squeaks in both clips that have a similar quality; the dominant frequency is similar, but the tree squeaks show more energy at that frequency. The second screen cap is a detail of the first, showing both calls and tree squeaks. The latter show a brighter orange, indicating more energy at a similar frequency to the calls’ dominant partial. The sounds are definitely different, but they can be hard to distinguish at the margins.
Steve’s effort, which took many hours, inspired me to revisit the recordings and specifically to reexamine possible responses to Matt’s anthropogenic double knocks and Phil’s playbacks over the course of the more than three hours when Matt’s recorder was running. I had concluded that the ADKs did not seem to have had an impact, but on careful re-listening, I’ve amended that view. Matt’s knocks do seem to have stirred up calls in reaction and to have generated several possible single or double knocks.
Listening through the recordings and especially to the ADKs and their immediate aftermath was a time-consuming and difficult process, especially because the knocks are very loud and tightly spaced. Matt used two wooden blocks (rather than dowels and a tree trunk or a knock box) and did not follow a specific protocol. Overall, his approach was more aggressive than Frank’s or mine, both in terms of volume and number of knocks, and a somewhat more restrained approach is probably advisable in the future. Nevertheless, if you assume (as I do) that ivorybills were present on this morning, these recordings may provide some insights into the efficacy (or lack thereof) of ADKs in generating responses.
This return visit to the recordings also supported my view that the putative ivorybill calls (recorded in the old search area) that Phil played back generated no reaction at all from the suspected ivorybills on the morning of the 15th. Blue Jays, however, appeared to respond, and I now tend to think those calls (though not all of those recorded in the old area) were Blue Jay, based on the apparent Blue Jay responses and on the harmonics. In retrospect, it’s unfortunate (but totally understandable under the circumstances) that playback of the Singer Tract recordings and other possible attraction methods weren’t tried. Perhaps another opportunity will present itself, although the events of March 15 were singular . . . thus far.
In the first of these two clips, the playback seems to have provoked Blue Jays to call faintly. In the second, in which the Blue Jay calls are easier to hear, they had been calling before the playback began.
By my count, Matt did 7 sets of ADKS and performed approximately 205 knocks in all. I noted six possible double or single knock responses (of varying quality) in four of the six series. These knocks occurred within seconds of ADKs. The temporal proximity between the ADKs and the possible DKs and SK in response make it less likely that Matt and Phil (to a lesser extent) would have noted them in the field.
I’m posting the relevant extracts below in unmodified form followed by clips with the interesting knocks amplified using Audacity. They should be audible through a desktop computer, but headphones will help. To repeat a strong caveat: Matt’s ADKs are very loud (which made this analysis especially difficult). I should also reiterate that I don’t consider myself particularly skilled at analyzing recorded knocks; I don’t have the greatest ear for intervals and have no direct field experience with Campephilus woodpeckers; my ability to interpret sonograms is also limited. Nevertheless, I’m sure these sounds are neither shots nor industrial noise (or duck wingbeats). With one exception (the fifth knock, which sounds like a single to me), I’m also confident that Matt was not the source of the sounds. Some of inadvertent bumping together of his blocks should be audible at various points, and it has a different quality.
The first set of ADKs was the shortest, involving only six, and these were very closely spaced. The first ADK in the series produced a possible DK in response. Matt began the series 15 minutes and 52 seconds into the recording, and there had been a kent call at 14:59. Both a possible DK and a kent call can be heard between the first and second knocks. An additional kent can be heard after the third knock (omitted here).
I did not find any possible double knocks in the second and third series, and there were only a few kent calls – one during the second and three during the third. There was a possible double knock in the fourth series, at 1:48.22, two seconds after an ADK.
During the 5th set, on the second clip, I found a possible single knock at 3:16. (Steve Pagans, who has an excellent ear, thinks it’s a closely spaced double.) I can’t rule Matt out completely as the source of this sound, but I think that’s a remote possibility.
Edited to Add: Playing the clip at a slower speed, reveals that there are two distinct knocks, the first louder, and leaves me convinced that Matt was not the source of this sound.
Also on the second clip in the 6th set, there’s a possible double knock at 30:26, approximately 2 seconds after an ADK.
On the final recording, during the 7th and final set, there’s possible DK after the 5th ADK in the series. It was preceded by a possible ambient DK about 50 seconds before Matt began the ADKs. The ambient knock is slightly buried behind some rustling, approximately three seconds into the recordings. To my ears, the DK in response sounds as though the first knock is softer than the second, something that’s uncommon but not unheard of for Campephilus woodpeckers. I’ve included both the entire relevant sequence and extracts in which I’ve amplified the knocks.
Unmodified clip with ambient DK and later DK in response to Matt’s 5th in a series of ADKs:
Ambient DK Amplified:
Amplified DK in response to ADK:
Finally, in listening to parts of Matt’s first clip again, I noted that there are a number of very distant kents. These are barely audible at normal volume and only faintly so on the amplified version. This suggests a highly mobile source (or sources) for the calls. It also suggests that there may be more calls on the recordings than the approximately 200 hundred I originally estimated. Steve noticed these calls too but elected not to include them in his compilation because the amount of amplification necessary degrades the sound quality. Thus, it may be difficult for some readers to hear these more distant calls.
The first few seconds of the extract below are unamplified to give a sense of the volume of other ambient sounds at the time. The kent calls come toward the end, and with one partial harmonic showing up faintly on the sonogram (the lighter colored dot near the left margin in the image below).
Amplified Distant Kents:
I owe readers the final installment of the “Bits and Pieces” series (hotlink is to the most recent installment). I anticipate that it will be my final post for this eventful year. Look for it just before Christmas.
Longtime readers of the blog have probably noticed the donate button and the advertising that now appears on the site. Project Coyote has been mostly self-funded from the start, except for a few donations from anonymous individuals and the Rapides Wildlife Association. Some used equipment has been passed on to us by other groups of searchers. I’ve long believed that we’d be able to document ivorybill presence (or go a long way toward ruling it out) with more consistent coverage in the area and a relatively modest budget.
At this point, remote recording units and a couple of additional cameras are at the top of the wish list. Ultimately, I’d love to be able to cover costs for our core group and to provide funding for one or two people to be in the area steadily, at least during February, March, and April. I can dream . . . Anyway, your contributions can help make some of this possible.
Before Frank’s passing, I had decided to ‘retire’ from active searching after this season, for a number of reasons – the sense that I had nothing further to say about feeding sign and the fact that I did not personally see or hear anything strongly suggestive of ivorybill presence in the 2015-2016 season among them. The lack of recent work on hickories was particularly discouraging.
Things started to change when Frank was in the hospital. It became clear that our search was important not only to Frank but also to his family and friends. A number of long-time, mostly quiet, enthusiasts and supporters (including Matt Courtman who had visited the area with Frank some years ago) reached out and encouraged me to continue and even to intensify the effort.
Shortly thereafter, Phil Vanbergen found some recent scaling of the kind that I think is diagnostic for ivorybill on two hickories, though it turned out the work was not as fresh as initially suspected. The trail cam capture of a PIWO removing a strip of bark from one of the trees led me to begin my first March trip in a somewhat pessimistic frame of mind. It didn’t take long for that to change – another ride on what I’ve taken to calling the IBWO-llercoaster.
I arrived in the search area on March 9 and met up with two out-of-state birders with whom Frank and I had been corresponding for some time. I showed them around the search area. They were impressed by the habitat, but we did not see or hear anything significant. On the morning of the 10th, I sent an email to some of the team expressing my frustration over not having had a “compelling recent encounter” and stating that my possible October sighting didn’t meet that standard (even now, I don’t think it compares to the March recordings.)
I was on my own on the 10th and had a slightly less discouraging day; I got my first opportunity to examine the scaled hickories Phil had found. This strengthened my suspicion that the recent PIWO work was “wake feeding”. Later, I met Matt for dinner and a strategy session.
Everything changed on the 11th. In addition to satisfying myself that the extensive scaling on the hickories was at least several months old and that the recent Pileated activity was likely secondary scaling (based primarily on the small bark chips); over the course of the day, we deployed three of our four trail cameras.
Even more importantly, we had auditory encounters in both the morning and the afternoon. Here is my write up from that day, with a few redactions.
At about 10:15, we were in close proximity to where we’ve had several possible contacts, most recently when I was out with Frank in October. We’d just deployed a second trail cam, and Matt had gone about 50 yards north and west of Phil and me. He texted and asked if he could do some DKs (he’s using two wooden blocks that he knocks together.) He did several, no particular pattern, mixed ASKs in with the ADKs.
I did not take notes, and my memory of the exact sequence is weak, but I heard 5-6 DKs and SKs coming from the east in response. If I remember correctly, there was at least some interplay between the ADKs and the DKs, meaning that there were a couple, and then a pause, then Matt DK’ed and there were replies. Matt said he heard 4-5, and I think Phil said he heard 3-4.
Whether or not I’m misremembering, it was far and away the most compelling series of responses I’ve ever heard, and I’ve done hundreds of ADK sessions. **** this was similar to what you encountered on your first trip, in the same general vicinity, but a lot more dramatic. In addition, there was no ambient foraging, and other than the responses, all we got was one PIWO drum from a different direction. Phil said that one of the DKs was very similar to the Pale-billed DKs he heard in Costa Rica last summer.
For the kents, we were at a different location a few miles away; the time was approximately 2:45 pm. Phil and Matt heard a number of calls, of which I only heard two. Of the two I heard, the first was on the low-pitched side, I’d say close to the pitch of the what Tanner called “conversational” calls on the Singer Tract recordings or what Frank and I called the “wonka wonkas”; it had a trumpet-like quality, maybe more than I’d expect for an IBWO, but still in the ballpark. The second was higher pitched and more tooty/reedy, very close to the Singer Tract recordings. The wind was dead calm for the second call, so it was not a tree squeak. In both cases, the calls came from the East.
. . .
So there we are. Quite a day. Now, if we could only find out what’s making the sounds and what’s knocking the bark off the hickories at the outset.
For those who missed it, here’s Phil’s recording of two of those calls – headphones or good speakers recommended. We did not record the knocks we heard in the morning.
On the 12th, Steve Pagans, Matt, and I returned to the location and heard 1 ambient DK and 2 SKs, at approximately 1:55 pm.
These sounds came from roughly the same direction as the calls we’d heard the day before. The possible DK was not as loud as the SKs, or as yesterday’s knocks, but it was distinct. Matt did some ADKs. There was a Red-bellied Woodpecker foraging to the south of the direction of the knocks. Matt’s ADKs seemed to induce it to bang more frequently and forcefully, but we didn’t hear any distinctly IBWO sounding knocks in response. Steve and I heard a single possible kent from the same direction as the possible SKs and DK. It was faint. Steve heard it better than I did and thought it was good; Matt didn’t hear it all. This was probably due to how we were positioned in terms of proximity to the sound.
Under normal circumstances I’d label this episode as a fairly weak possible, marginally worthy of mention on the blog. But given the location, it seems more significant.
The 13th was also eventful. Matt and I opted to return to the area where we’d heard the knocks on the morning of the 11th and give the other location a rest. Here’s my write up of the morning’s possible auditory encounter.
We decided to do a mix of playback and DKs at 9:40 AM. I did about a minute and a half of playback, using the iBird app (3 rounds – 28 seconds of Kents, “conversational” calls, and tapping). Matt followed with perhaps a minute of knocking wood blocks together. Over the course of the following five minutes, we had several knocks. Initially, Matt heard a single that I think I missed. It was followed by a very loud knock coming from the East. It was VERY loud and clear, what Frank would have described as some banging on a tree with a baseball bat. Shortly thereafter, another sound came from my left, roughly north of us. Matt heard it as a single, but I heard it as a double, with the second to my ears perhaps the closest thing to what Tanner described as an echo of the first I’ve ever heard. After that, we heard another loud single roughly from the southwest. The last was more distant and somewhat less striking.
The first single knock and the one I heard as a double were astonishing. There’s no doubt in my mind or his that these were neither mechanical sounds nor foraging. I am kicking myself hard for not having my recorder running; I’ve gotten too jaded about auditory encounters, and it’s a little tough to manage both recording and generating sounds.
A little later, I found a dying chestnut oak with some mildly intriguing feeding sign. There were some huge, thick bark chips on the ground and this, more than the appearance of the work on the tree, struck me as potentially suggestive; this is the first interesting work I’ve found on an oak in several years.
Matt and I returned to this location on the morning of the 14th. Matt did ADK series on the half hour until shortly before noon. It was a cold and windy morning, uncomfortably so. We heard nothing of interest.
On the 15th, I headed for New Orleans and my flight the following morning. Phil and Matt returned to the woods and captured numerous calls between 7 and 11 am. When I heard the recordings I cleared the decks and made arrangements to return as soon as I possibly could.
Patricia and I were back in the woods by lunchtime on the 23rd. Louis Shackleton – a good friend, professional photographer, and birder who happened to be in Louisiana – joined us on the 24th. We didn’t see or hear anything of interest and left early ahead of predicted heavy rains.
At shortly after 11:00 am on the 25th, Patricia and I heard some possible double knocks in apparent response to some very aggressive knocking on my part; two of these knocks came from roughly north and one from the east (the same direction from which the March 15th calls were coming). I’m still reviewing the audio from this trip and may have additional material to post in the future.
I went out alone on the 26th, returning to the same vicinity, and did not see or hear anything interesting.
We were rained out on the 27th. On the 28th, I found a large cavity not far from where the calls were recorded. It does not appear to be fresh enough to be a recent nest, but we plan to target it with a trail cam in the event that it’s being used as a roost. This find illustrates how difficult it is to spot cavities in our search area – six people had spent the better part of multiple days in the immediate vicinity before I noticed it, and the snag is in plain view.
More storms came through on the night of the 28th, and the next morning Patricia and I decided to take a break from the “hot zone” and instead visited the area where Phil found the recently scaled hickories and where Matt, Phil, and I had heard knocks on the 11th and 13th. We found that one of Phil’s scaled hickories had lost its top, which gave me a chance to examine one of the scaled areas up close. As expected, the wood was somewhat punky, and and the bark was fairly easy to remove by hand.
We also discovered that the top of one of our target hickories had been blown off. The tree shows signs of beetle infestation, which gives us reason to hope that it will be visited by woodpeckers before too long.
It was interesting to get a close look at this freshly fallen top and examine how hickory bark separates from the trunk under these circumstances. While it seems to come free fairly easily in very large strips, the bark is extraordinarily tough and strong. When fresh, it’s flexible but very hard to break; doing so requires twisting, and it won’t fracture. Within about 48 hours the piece I collected had dried out and become surprisingly hard. This further reinforced my view that Pileated Woodpeckers are not anatomically equipped to scale large chunks of bark from live or freshly dead hickories.
It was a beautiful day in the woods, and some of the other highlights included recently hatched Wood Ducklings, a posing Yellow-crowned Night Heron, and the first ‘gator (a small one) I’ve ever seen in the area.
The next morning, I returned and redeployed a second camera, which had been trained on another nearby hickory, to the one with the downed top so that we can cover the entire stub.
We spent the morning of the 31st in the area where the calls were recorded before catching an afternoon flight. We did not note any interesting sounds while in the field, but after listening through Patricia’s recordings, I noted the possible double knock discussed in the previous post.
I’m planning two more trips before summer. I anticipate that we’ll have all cams deployed and have high hopes for the hickory stub.
Meanwhile, I thought I’d throw in some additional images that may help to convey what a special and magnificent place this is.
To expand on some of the data included toward the end of the March trip report (which is worth reading in in conjunction with this post), I thought it would be informative to provide a season by season and sector by sector breakdown of the scaling I and others involved with Project Coyote have found since the spring of 2012. To do so, I’ve gone through my notes and photographs and have done my best to reconstruct the data collected. While not complete (I’m quite sure a good deal more scaling was found in Sector 3 during 2013-2014, for example), I think this breakdown is a fairly accurate reflection of what we’ve found over the years.
As discussed in previous posts, I think extensive scaling on hickory boles is the most compelling for Ivory-billed Woodpecker. Bark on this species is thick, dense, and usually remains very tight for a long time. Extensive scaling on sweet gum boles and oaks (upper boles and large branches) is second among work that I’ve found. Work on small boles, and higher and smaller branches is somewhat less compelling and is more significant for its abundance. Some of the high branch scaling and work on smaller boled sweet gums may well have been done by Pileated Woodpeckers (and possibly by Hairy Woodpeckers), but the abundance, the presence of large bark chips in many cases, the way it appears in clusters, and the fact that Pileateds scale infrequently suggest a different source for much of it.
I have excluded all work where squirrels are suspected but have counted one tree, a hickory found this year, on which the work could well have been that of a Hairy Woodpecker. Hairies do forage for Cerambycid beetles just under the bark, but they’re only capable of removing tight bark in small pieces; their work on hickories is perhaps more accurately described as excavation through the bark.
The trail cam images toward the end of this post are the best we have (out of many thousands of hours of coverage) showing how these species forage on suspected ivorybill feeding trees.
All trees were live or recently dead (twigs and sometimes leaves attached). All scaling was on live or recently dead wood.
Sweet Gum (Liquidambar styracifula)
Sector 1: 46
Sector 2: 8
Sector 3: 51
~15% had scaling on boles (a few of these were large trees). The majority of work was on crowns, including larger branches. Fallen trees were included when woodpecker involvement was evident and bark was tight.
Bitternut Hickory (Carya cordiformis)
Sector 1: 3
Sector 2: 4
Sector 3: 7
All trees were standing; scaling was on boles and was very extensive (the tree shown on the homepage is one example) with one exception from this year . Insect tunnels were visible in all examples. An additional hickory with a modest amount of high branch scaling was found in Sector 1 this year but was not counted for this analysis.
Oak (Quercus) spp.
Sector 1: 1
Sector 2: 4
Sector 3: 0
All oaks had scaling on large branches; one also had some on the bole. All oaks in Sector 2 were found in a single cluster.
We have some information on forest composition in Sector 3, and it appears that sweet gums make up approximately 19%, oaks upwards of 35%, and hickories somewhere under 10%. Sectors 1 and 2 may differ and be more varied in overall composition.
The overwhelming preference for sweet gums relative to their abundance stands out. The scaled oaks are a mix of species, one Nuttall’s, one willow, the others unidentified.
In Sector 3, I am treating the compact stretch from the location of Frank Wiley’s sighting last spring/downed sweet gum top where we had the camera trap to just south of our current deployment as a cluster. The estimate of 23 trees being found in this area is conservative. I have only found one instance of recent scaling north of the location of the downed limb/Frank’s 2015 sighting. The main cluster has been in the same vicinity this year and last, with additional work scattered around farther south. Two of the hickories are within 30 yards of each other, approximately half a mile from the cluster, and one was on the edge of the concentration.
It also may be significant to note that we found a cluster of old but intriguing cavities in the same vicinity as the Sector 3 concentration in 2013-2014. Most of these seem to have fallen. The difficulty we’re having finding active, suggestive cavities is vexing, and may be the most compelling reason to be skeptical about the presence of ivorybills in the area. At the same time, finding Pileated cavities is difficult, even in defended home ranges.
I’m treating Sector 1 as a single concentration; the vast majority of the work is on a natural levee where sweet gums are abundant. The entire area is considerably larger than the other clusters, but given the abundance and ease with which we’ve found sign there over the last five seasons, I think it constitutes one area of concentration.
In Sector 2, there was a small cluster in the area where I recorded putative kent calls in 2013, with work found in 2012 (spring and fall) and 2013. Because the area is small with open sight lines, I can be confident there has been no recent work there since late in 2013 (I last passed through it with Tom Foti back in March of this year.)
The sweet gum work Tom and I found on that day was perhaps half a mile north of this cluster, within 100 yards of the hickory on the homepage. The other hickories found in the 2013 and 2014 seasons were not far away, no more than 500 yards apart as the crow flies.
There’s obviously some bias here, since there’s a relationship between finding feeding sign in a given area and spending time there. Nevertheless, I have little doubt that the putative ivorybill work tends to be clustered. I also have little doubt about the strong preference for sweet gums, since I’m not looking at tree species when I look for scaling. The degree to which sweet gums are favored has only become clear over the last year or so.
Frank pointed out this data does not reflect most of the scaling that likely exists in relatively close proximity to the Sector 3 cluster but cannot be quantified because it is in an area we have intermittently visited due to inaccessibility. Only two or three examples are from this area, which has been visited a handful of times.
I don’t expect to return to our search area until sometime this fall, but I hope that my schedule will allow me to spend a lot more time in the field next season. Overall, this was a challenging week due to high temperatures and severe back pain that troubled me from the end of the first day on. Nonetheless, it was a productive trip, and weather conditions were generally tolerable – hot and humid but not unbearably so, with daytime temperatures mostly in the high 80s. Woodpeckers, except for Red-bellieds, were generally quiet and unobtrusive. The only Pileateds I saw were responding to playbacks, and while I didn’t keep count, I’d estimate I heard their vocalizations an average of 2 or 3 times a day.
In contrast to winter and early spring, the woods are filled with other sounds – songbirds, frogs, cicadas, squirrels – making it much harder to separate signal from noise. Green frog calls can sound a little like double knocks at a distance, especially if you’re walking, and the squirrel calls in this recording were intriguing enough to capture, as only the somewhat kent-like sounds were audible to me in the field, something for other searchers to bear in mind.
I had a 6 am flight out of JFK. After arriving in New Orleans, I met Frank Wiley for coffee and then drove to his house, changed clothes and got to the search area at a little after 2 pm. The area I visited is the one closest to a parish road. This is a part of the southern sector in which we’ve consistently found feeding sign since 2012 and where I found a number of recently scaled trees in March of this year. Despite full leaf out, I was able to find quite a few more recently scaled trees in the general vicinity of those discussed in the most recent trip report.
Unfortunately, and perhaps because my attention was on looking for feeding sign, I got somewhat turned around and wandered considerably farther south than I had intended, running the risk not only of trespassing but also of getting stranded in the woods. I noticed this at about 6 pm. Fortunately, I wasn’t too far from the road, just well south of where I wanted to be. It took me a half hour to reach the road (at which point I noticed my back was hurting badly) and another ten minutes or so to get to the car. I didn’t sleep much or well that night, despite having been awake since 3:30 am.
My back continued to bother me, so I tried to take it easy by spending the morning in the most accessible part of the search area. I found a few additional scaled trees, some with old work and excavation that seems consistent with what Tanner described, others with scaling that looked fresh.
Travis Lux, a radio freelancer working on an ivorybill story, spent the morning in the field with me. (Most days this week I could only manage being out from around 6 am – 1 pm.) We visited the northern sector. I did not find any new feeding trees.
We passed the large downed limb where we had a camera trap for some time, and there has been no fresh work on it since the flooding in March. And only a small quantity of bark has been removed since the camera was deployed.
This may be significant, since it seems likely that common animals with small home ranges would return repeatedly to the same feeding spot. In the case of this limb, it seems to have been scaled by something unknown, prior to our camera deployment and again a little over a month later. Squirrels, Red-bellied, and Pileated Woodpeckers were captured or seen on the target limbs, but they did no scaling. As I’ve mentioned previously, in most instances, we’re finding that trees are visited by whatever’s scaling them once or sporadically over a period of months.
We continued southward into the area discussed in the last trip report; we’ve found feeding sign regularly in this small area every season since 2013-2014. I did not find any new feeding trees: however, there was additional scaling on a couple of the trees found in recent trips, most notably the large dying sweet gum below (the next to last image in the post). I’m hoping that Frank will be able to train a camera on this treetop once our old Reconyxes have been repaired. The resolution on our other cameras is too poor to aim them so high; the same may be true of the Reconyx cams, but the quality is somewhat better.
We did a stake out in the area for a couple of hours but did not see or hear anything of interest. On the way out, I noticed that one of our suspected feeding trees had some very fresh scaling on it. This is a small tree with thin bark, and the chips were mostly very small. I do not suspect this to be ivorybill work and have a hunch that it was done by a Hairy, taking advantage of scaling that had been begun by another species.
I returned to the part our search area that’s most readily accessible from the road, so I was in the woods before sunrise. I found a few additional recently scaled trees, some with very large chips at the base. One of these was heavily scaled on the bole as well as on the branches, and although the bark was loose in some spots; it was tight in others. The presence of twigs and small branches suggests that it had died fairly recently, even though there were signs of Pileated Woodpecker excavation on decaying parts of the bole.
Phil and Eric Vanbergen joined me, and we returned to the area I’d visited the day before, again getting into the woods early. We found a six more scaled trees, took GPS points, and measurements. The trees were all live or fairly freshly dead. All were sweet gums, as has been the case for virtually all trees found this season (with two possible exceptions, one of which is shown in the May 22nd entry). Diameters of the trees measured were 14.7”, 19”, 21”, 25.1”, 26.2”, and 27”
Four of the six trees listed above were found in pairs, about 5’ apart in one instance and 20’ apart in the other. In the case of one pair, a long dead sweet gum and a live hickory within 30’ also showed some older scaling. Most of this work was recent but not fresh. We found large chips at the base of the pair of trees that are 5’ feet apart; these were probably a few months old.
While I did not keep count, and we only took coordinates for a few of the trees found this time around, I’d estimate I found a total of 15-18 recently scaled sweet gums in and around the southern concentration described in the last trip report.
The Vanbergens were along again. It’s refreshing to spend time in the woods with young people (Phil’s in college and Eric’s in high school) who know and love nature, something that seems to interest fewer and fewer people in their age group. They have suggested some interesting strategies for searching, and I’m looking forward to their participation next season.
We went to the northern area, arriving at the scaling concentration at around 7:30. We staked out feeding trees until around 10 with no results.
Here are some of Eric’s wonderful photos: cottonmouth, pale lobelia, bark scaling, swamp milkweed, and another cottonmouth. He identified the plants.
After that we headed further south to an area they hadn’t visited before. We found a little bit of fairly recent scaling on a dead hickory about 20 yards from where I found a heavily scaled hickory in 2013. The scaling is not extensive; it’s clearly targeted at larger Cerambycids, but given the small patches, Hairy Woodpecker is a distinct possibility. I was unable to find any fresh chips, so the work is probably several months old.
I returned to the northern area alone and spent the morning staking out the same large feeding tree. I watched Red-bellied Woodpeckers flying to and from the tree sporadically, usually spending very brief periods pecking and gleaning on both scaled and unscaled areas and drumming from time to time. At 7:30, the male landed at the top of scaled stub and called. The female arrived; they copulated, and she flew off. He departed a few seconds later. At 8:30, I recorded the squirrel calls, and at 10:35, one of the RBWOs landed near the top of the scaled stub, peered around at me, and eventually started to drum. I called it a day shortly after noon. Here’s another image of the sweet gum top I was staking out, to give a sense of how extensively scaled it is in the crown.
I hiked out, following a rather circuitous route. A few hundred yards from the concentration, I found a recently dead sweet gum with a few small scaled patches but no extensive work. I think this is another indication that this scaling is not being done by a common, evenly distributed species. Work tends to appear in bunches, with scattered sporadic examples elsewhere, but in the two areas discussed in this post, bark scaling on deciduous trees has been abundant in concentrated locations, over several years, and is much harder to find and scattered outside of these “hot zones”.
On the 24th, I drove to New Orleans, stopping in Lafayette for lunch and ivorybill talk with Wylie Barrow and Tommy Michot.
I realize this has been a very image-heavy post. I sometimes think it’s hard to convey the quantity and unusual nature of the bark scaling we’re finding in this area and hope this does a somewhat more effective job at making it clear than some previous efforts.
That’s all for this season. I’ll be doing some additional posts on old material as well as one on foraging sign concentrations and tree species in the weeks ahead. I may also upload a lot more images of feeding sign to Flickr for those (if any) who haven’t seen enough of it. And of course, if there’s anything to report from Louisiana, you’ll read it here. I hope that the insights and data that have emerged this season will guide us next year.
As usual, much of this report will be focused on bark scaling. I found an unprecedented amount of fresh work this trip, a total of 29 trees, all sweet gums. I only counted live and freshly dead trees that appeared to have been scaled within the last year, and probably more recently than that, in most cases. As will be discussed, I was able to ascertain that 11 of these trees had been worked on no earlier than March 15th. I was selective about what I included in the count, relying on my years of experience looking at scaling and how its appearance changes over time and this passage from Tanner for the criteria:
Ivory bill sign shows as bare places on recently dead limbs and trees, where bark has been scaled off clean and to a considerable extent. Pileateds do some scaling too, but it is usually confined to smaller limbs and those longer dead. Freshness of the sign can be judged by any appearance of weathering, which will soon turn bare wood a grayish color. Extensive scaling of the bark from a tree which has died so recently that the bark is still tight, with a brownish or reddish color to the exposed wood showing that the work is fresh, is one good indication of the presence of ivorybills.
We had a number of visitors during my stay. Tom Foti joined me again on Tuesday and Wednesday, and Phil and Eric Vanbergen came along on Friday. I appreciate the Vanbergens’ help in collecting the data I’ll be discussing. It’s great to have such enthusiastic young people involved. Meanwhile, John Williams (Motiheal from ibwo.net) visited and spent four days in the field with Frank. Both John and Frank are planning to provide their own accounts, and those will be posted in the weeks ahead.
A general note about the week, leaf out progressed rapidly, and the change between Sunday the 20th and Saturday the 26th was dramatic. Nonetheless, I was able to find a good deal of feeding sign later in the week.
I arrived on the evening of Saturday, March 19th, and Frank and I spent the 20th in the northern sector. There had been severe flooding in the area earlier in the week; the waters had receded – we suspect by the 15th or 16th and certainly no earlier than the 15th. One of our trail cams, placed about 4’ above the ground, was completely overtopped, ruining the card and probably the camera as well. Such floods are exceedingly rare, perhaps a once in 500 year occurrence in the area. Fortunately, flooding tends to recede rapidly, but crossing both permanent and seasonal water bodies remained a much bigger challenge due to deep water and slick banks. The most stunning aspect of the flooding was the near total scouring of leaf litter in many parts of the search area, leaving bare soil and deposited silt visible. The landscape was transformed, and familiar spots looked radically different.
Frank often describes walking through the forest on dry leaf litter as “walking on cornflakes.” The absence of leaf litter limits the noise made by walking. This may be advantageous between now and late fall. Unfortunately, I anticipate being able to visit the area only once more before summer, probably in June.
The flooding had another benefit this trip. The absence of leaf litter makes it much easier to find fresh bark chips on the ground and to determine with some degree of certainty when scaling has taken place. The flood waters receded no earlier than March 15, so all fresh chips found below trees where the leaf litter had been scoured were no more than a week old.
When we reached the vicinity of the downed top, first discussed here, we heard a loud single knock. Frank’s initial reaction was that it might have been a gunshot, but we both agreed that the sound seemed to have come from a nearby source; we heard no other shots that day and saw only one vehicle, almost 2 miles away. Later in the morning we heard a couple of weak possible double knocks and later a very good sounding one.
We also found a little bit of scaling just north of the northern concentration discussed below. While some of it looked to be quite fresh, we did not find any bark chips.
The scaling in the first of the above photographs is somewhat marginal, as only a single smaller upper limb is involved. While I’m unsure, I don’t think I counted either of these trees, as I only started keeping track later in the week; both examples came from very close to the northern cluster discussed below.
I was on alone on the 20th, and I returned to the same area. I found a good deal more scaling.
In many cases, the scaling shows sign of progressing from treetops down, as Tanner described.
The detail of the small tree, scaled down to where small branches are still in leaf, is at the edge of a small pond around or in which I found five other trees with recent scaling on them, as well as two more with older work (not counted).
There was new work on one of the trees I found last month, the larger one in the background, below. I found several other scaled trees in the immediate vicinity, including the one in the foreground, on which we’ve now deployed a camera, and much of that work was fresh too. I chose a spot for a stakeout and spent about an hour watching the treetops in this area of concentrated work. This location is 140 yards south of the small pond described above and is at the southern boundary of the cluster. During the stakeout, I heard a loud single knock that seemed to have come from the vicinity of the small pond.
As I was leaving, I passed the pond again and found what appeared to be new scaling on one of the trees at its edge. There were fresh chips in floating in the water at the base.
Tom Foti arrived on the morning of the 22nd. We spent the day in the one of the southern areas where we’ve found concentrations of bark scaling in past years and where there have been both possible visual and auditory encounters. We found several scaled trees in this area but did not see or hear anything.
I met up with Tom on the morning of the 23rd; I had decided overnight to be more methodical in my approach to documenting scaling. I’ve been so focused on what might be diagnostic that I haven’t attempted to quantify what I’ve found thus far and haven’t kept detailed location information. Thus, it seems like a good idea to start keeping better track. This should prove useful if we can document that ivorybills are present and that they are responsible for the bark removal.
Tom and I heard 6-8 likely kents at ~9:00 am, this at the downed top where we had the camera, the same location where Frank had his sighting last spring. The calls came from three directions, south, east, and west.
We headed south and met up with Frank and John in the core of the northern concentration, south of the pond. We did an extended playback series; John will have more to say about the specifics in his post. We all heard a nearby double knock during the playback; Tom, John, and I were sitting close together near the speaker and thought it was a single, but Frank, who was positioned closer to the source of the natural sound, called it as a double.
We found some very fresh bark chips (moist with sap) at the base of a 12” DBH dying sweet gum that has areas of scaling high on the bole. The tree (which is shown above) is only a few meters from the one found last month. We’ve deployed a camera aimed at this bole. Given the quantity of activity in the area and the evidence of return visits to feeding trees, we hope to get some hits before long.
We removed a piece of bark from a looser spot on a nearby downed tree (which had been fed on by woodpeckers both before and after it fell). Beneath the bark were Cerambycid larvae, pupae that I also suspect are also Cerambycids, and what I think may be a very young Elaterid larva. We placed some of these larvae and pupae on the piece of bark to illustrate. We suspect that Allen did the same for what became Plate 10 in Tanner.
On the way out and not far from the cluster, I spotted what appears to be the start of a large, irregularly shaped cavity. We’ll monitor this and see whether there’s any further excavation.
It rained heavily on the morning of the 24th. I spent part of the afternoon trying to take measurements but didn’t have much success, since I was using an ordinary tape measure.
On the 25th, Phil and Eric Vanbergen joined me and we took measurements in the two areas where there are concentrations of scaling, finding several more trees in the process. When I got back to Frank’s, the forester’s DBH measuring tape I ordered had arrived, making it possible for me to take measurements on my own.
I spent the 26th measuring suspected feeding trees in the southern area and found several more with recent work on them.
Except for feeding sign, I did not see or hear anything suggestive of ivorybills during my last three days in the area.
Now I’ll turn to some of the data I collected this week.
I counted 29 suspected recent feeding trees in the two areas, 13 in the northern sector and 16 in the southern. I did not count work that appeared to be more than a year old or work that was limited to very small branches.
The areas are 2.05 miles apart. The northern area was logged (probably partially) in 1905, although there may have been some later selective cutting. The southern area was logged in 1935. Forest composition is somewhat different between the two areas, with sweet gums seeming to be less predominant in the southern one. In the southern area, the scaled trees are in a narrow, almost linear strip with an area of .13 square miles/83.2 acres/33.67 hectares. The northern cluster is more compact and polygonal, with a total area of .03 square miles/19.2 acres/7.7 hectares. Within both areas, scaled trees were often found in groups of 2-6 – 11 out of 13 trees in the northern area and 11 out 16 in the southern. (This includes the cluster in and around the pond, which is perhaps 30 meters in diameter, but otherwise applies to trees that I estimated to be 20 meters apart or less.)
Scaled trees ranged from 6.5” dbh to over 5’ (estimated) for a gum with a split trunk, one stem live and the other dead. All but 3 inaccessible trees were measured.
76% of the trees were alive, sometimes just barely, with scaling on dead or nearly dead limbs or boles. There was scaling on live parts of one or possibly two of the trees.
Though we have found scaling on boles of larger trees in the past, all trees scaled on boles were 12” DBH or less. While these measurements may not be meaningful absent a random sampling of trees in each sector for comparison, I thought the numbers might be of some interest even now, especially in light of the recent discussion of Tanner:
This is obviously a very small sample, but I think it’s interesting nonetheless. The three smallest trees in the northern sector were all in or near a pond that appears to have had its outflow blocked in recent years. They probably died due to the change in hydrology. But for that difference, there seems to be an even greater favoring of 25-36” DBH trees than found by Tanner, and this is so even in the less mature southern sector (again without data on overall composition). This year, feeding sign has been found exclusively on sweet gums. We’ve found a few scaled oaks over the years and more bitternut hickories; I suspect the latter are being fed upon at a high rate relative to abundance. We’ve discussed doing some random sampling for tree size and species, but given our limited resources, this may not be worthwhile or feasible at present.
Of course, none of this proves that ivorybills are in our area, but I think it’s another indication that they are. The best-case scenario is that the dramatic increase in scaling this year and in this season is related to there being young in a nest or nests.
I flew into Houston on February 4 and arrived at the search area on the morning of the 5th. Frank’s work schedule had precluded him from returning to the search area during my absence, and he was unable to get time off to join me this trip.
Tommy Michot visited on the February 5th; we went to the northern sector, and passed the downed sweet gum top (actually a limb) found in April of last year. Project Coyote had a camera trained on it for some time but took it down due to equipment failure. The main stem, which reaches from the ground to about 20 feet up, had been scaled extensively, down to the base, over the course of the last month. Some of the work had been done no more than a few days prior to my arrival based on the condition of bark chips found at the base.
We have a camera back on this top but have low expectations, since so much bark has been removed that it makes a much easier target for other species of woodpecker. While I don’t believe in the “curse of the ivorybill”, individuals and small groups of self-funded searchers face enormous obstacles and are dependent on equipment that’s often unreliable.
Tommy and I measured a number of the largest trees in the area, and the biggest oaks and sweet gums are around 4’ DBH, with many more in the 3’ range. Here are some of the highlights: two Nuttall oaks: 137 cm/53.94”, 119 cm/46.85″; swamp chestnut oak 110 cm/43.31” four sweet gums: 124 cm/48.82”, 123 cm/48.43”, 110 cm/43.31″, 109 cm/42.91”.
While ours was not a random sample, this table from a 1986 paper by Tanner (on data collected in the Singer Tract in 1938), is interesting for the sake of comparison.
In his 1944 report on the Singer Tract, Richard Pough described sweet gums in the 5’-6’ DBH range as being characteristic of old growth conditions, and such trees were not uncommon in the 19th century. Impressionistically, at least, most of the ~4’ DBH sweet gums in our area are moribund and are likely to have lost their tops. I know of only one gum that appears to be in the 5′ DBH category. As of 2009, the national champion sweet gum had a DBH of 5’4.6″. The tree below could be close to that.
Many, perhaps most, gums have at least some beaver damage. This may be contributing to the earlier mortality, both by stressing the trees directly and by creating the opportunity for beetles to infest them. I have long suspected that the decline of the beaver could have contributed to the IBWO’s disappearance, since beavers directly damage trees by gnawing and also stress or kill them by altering hydrology.
Beavers were extirpated from much of Louisiana by the early 19th century. As of 1931, populations were restricted to the Amite and Comite rivers in the southeastern corner of the state; they were reintroduced in other areas in 1938 and had established themselves in 21 parishes as of 1951. (Wylie Barrow, pers. comm.) Range expansion continued into the 1990s and after. They’re now considered a pest animal and appear to be found in all parishes. A recent paper suggests that the introduction of beavers into Magellanic Woodpecker habitat may have benefitted that species.
I was on my own on February 6th, and I went and staked out the downed top for the better part of the morning. Nothing landed on it except for a Red-bellied Woodpecker that pecked and gleaned but did not scale bark or do any excavating. At approximately 9:30, I did a very aggressive series of ADKs. I heard a couple of loud single knocks that seemed to come from no more than a couple of hundred yards away and also a possible double knock. These came during a period when I was standing, moving around, and doing the ADKs, so I did not hear them very well. In addition, there were a few distant gunshots within about 15 minutes after the series, so I’m not very confident about what I heard. (These were the only shots heard all day.) I found some scaling the next day a couple of hundred yards away (discussed below). This gives me some reason to think the SKs were a reaction, not shots. Still I’d place these in the weak possible category.
One highlight of the day was watching a pair of Red-shouldered Hawks in the act of mating.
I returned to the same area on the 7th, with two cameras to deploy. One is aimed at a large sweet gum stub, about 20’ tall and well over 3’ DBH that I found last trip. The top had broken off shortly before my arrival. While it’s not discussed in Tanner, T. Gilbert Pearson, who was the first modern ornithologist to observe the Singer Tract IBWOs, described this type of “stump” as one of the species’ preferred feeding sites. This is a tree on which I found high branch scaling last year, before the top broke off. I expect this to be a long-term deployment.
I also redeployed a camera on the downed top, although we’re not very hopeful about that location, since the scaling is so extensive and the bark has been loosened in many of the remaining unscaled areas.
I walked south for a couple of hundred yards and found very fresh, large bark chips at the foot of a live sweet gum (there were two large gums ~3’ dbh about 10’ apart). There was extensive scaling on live or recently dead high branches of one or both of these trees. Because there had been a major rainstorm and accompanying minor flooding a week before and the chips were mud free, I can be sure the scaling took place after the rain, and since Tommy and I had spent considerable time in the area examining some other nearby scaling two days before, I strongly suspect this work was done on the 6th. I can’t help but wonder whether the possible single knocks came from whatever was doing the scaling; that would be consistent with my immediate impression when I heard them, both in terms of distance and direction. Nonetheless, my confidence level about the SKs is low given the gunfire.
I don’t think the scaling and bark chips are consistent with squirrel; the chips are large and thick and do not show signs of having been chewed off; the ones collected weighed over five pounds.
There was a little excavation and exit tunnel expansion (visible in the first image above) associated with the scaling; and it has the generally clean edges and lack of layered, flaked off appearance around the edges or on the chips. The leaves and gumballs are attached on most of the limbs, indicating that they’re alive or very, very recently dead, so the bark is almost certainly tight. This is about as good as it gets when up-close examination is not an option
I met Tom Foti, who came in from Arkansas, on the morning of the 8th. Winds were high, with gusts approaching 50 mph. We decided it would be unsafe to venture into the woods, so we drove around the edges of the search area looking at the surrounding upland forest, much of which is impressive and mature. Tom is very enthusiastic about the area, ivorybills or not, and we’re hopeful that steps will be taken to protect and manage it appropriately. The car ride was a running lesson on southern forest ecosystems, and as I told Tom, I’ll count myself lucky if I retain 10% of what I learned.
The next morning, the winds had dropped enough to make it safe to head for the swamps, and Tom and I visited the southern sector, an area where we haven’t spent much time lately. As mentioned in some previous posts, there has been a significant uptick in four-wheeler activity in the area, and it’s heartbreaking to see the destruction these callous individuals are causing. Fortunately, the damage is almost entirely limited to the periphery, and the deeper parts of the bottom are unscathed. The habitat types here are somewhat different, and the logging date is more recent, but it remains very impressive. We walked a long way and went to places I had never been, including a lower-lying flat with tree species I haven’t noticed elsewhere – shagbark hickory, bitter pecan, and overcup oak.
We saw no recent feeding sign in any of these areas, except for some older work on a small sweet gum that I described as being about a grade B-.
We then looped back along a different track, passing the spot where I recorded calls in March of 2013 and where we’d had a concentration of feeding sign in 2012 and 2013. We found nothing until we reached a location farther north that is within 100-200 yards of the tree shown on the homepage. Tom spotted a group of trees with bark scaling, some on boles and some on branches. Once again, this was not “grade A” work, but the concentration makes it more interesting than if it were one isolated example. We did not find any chips at the base of the snag that had been scaled on the bole, and the high branch work is not as extensive some.
It’s worth pointing out that on many days, I’ll walk for hours and see nothing and then find either a dramatic example of scaling or a small cluster of it. Tom and I had probably walked 3.5 miles or more before finding this little cluster.
I was on my own again on the 9th, and I opted to go on a death march to retrieve a trail cam from a tree deep in the swamp and proceed north from there. The tree is a large blown down sweetgum discussed and shown here. There was some fresh scaling on it that I suspect was done by a Pileated Woodpecker. There are nearly six weeks of images to go through, so it will take some time before we find out if there were any captures.
As on the previous day, I walked for a couple of hours without seeing or hearing anything suggestive until I got to a part of the area we haven’t visited since last year, perhaps a quarter mile south of the southernmost point Tommy and I had reached earlier in the week. I found old sign, some of which was fresh last winter and some of which was older. I then found some fresh work on two trees in close proximity to one another. Some of the scaling was on a downed tree but was clearly done by a woodpecker, with chips and other characteristics that I consider to be suggestive. Since the chips were caked with mud, the scaling was a little over a week old. The other work was on one high branch, but conditions made it impossible to look for chips.
On the return hike, I found what I’m quite sure is Pileated Woodpecker work on a recently dead or dying hickory. Since we’ve found a number of hickories that we suspect have been scaled by Ivory-billed Woodpeckers, this was an unusual opportunity to do a direct comparison. In my view the work on hickories is the most compelling for ivorybill due to the density and tightness of the bark and the hardness of the wood. There are pronounced differences in the presumed Pileated and suspected ivorybill work on this species.
The work on the homepage is suspected ivorybill. It is extensive, with huge contiguous areas, perhaps 20% of the entire surface, completely stripped, with evidence of bill strikes targeted at exit tunnels. The Pileated work is spotty by comparison. The bark chunks scaled from the tree on the homepage were large, dense, and thick, and there were no pieces of sapwood among them. By contrast, the suspected Pileated work involves very small pieces of bark that appear to have been removed by digging rather than scaling; there were also a few pieces of punky wood among the chips.
The next morning, I drove to the Wetlands and Aquatic Research Center (formerly the National Wetlands Research Center) in Lafayette and met with Wylie Barrow, Heather Baldwin, Tommy Michot, and Philip and Eric Vanbergen. (Two young enthusiasts who will be helping us out.) Frank joined us briefly, and then Wylie, Tommy, the Vanbergens, and I went out to lunch. It was an exciting and thought-provoking day, and the Research Center is an incredible facility. Wylie and Heather shared their comprehensive and in-depth analysis of conditions in the Singer Tract in Tanner’s day. They’ve amassed an array of materials encompassing land records, Civil War era maps, and stereographic aerial photographs. Their research far surpasses my own speculative effort. It covers the finest details – roads, improved and unimproved, snag densities, tree mortality, conditions around roost and nest sites, as well as conditions in other locations where ivorybills were seen. Tom Foti has done complementary research on hydrology, soils, and vegetation.
Their presentation convinced me that I’ve been too hard on Tanner in some respects. There was a little more old growth in the Singer Tract than I had inferred from the Pough report and some of the historical documents. Nonetheless, the characterization of the Tract as a whole as “virgin” forest is somewhat misleading, since over a quarter of it was second growth, and some of it fairly young. Heather and Wylie have graciously given me permission to summarize some of their findings.
When Tanner began his study, 72% of the Singer Tract was old growth. (Tanner estimated it at over 80%.) Logging in 1938 reduced that percentage to 67%. The ridges, which Tanner deemed to be the best ivorybill habitat, were actually the least likely areas to be old growth. (Tom Foti’s analysis also points to a preference for higher, drier locations.) The regrowth percentages for each landform in Tanner’s day are as follows:
Low ridge (23%)
Total on ridges (32%)
Low flat (4%)
Cypress brake (4.5%)
For the most part, the second growth forests were not particularly old, as has been suggested in previous posts. According to Heather, most of these areas only started to regrow in the 1880s and 1890s, “due to consecutive depressions and low cotton prices”. Thus, parts of the Singer Tract were relatively young second growth, and this included one of the ivorybill home ranges and one that Tanner deemed to be “best” – Mack’s Bayou.
The nature of the habitat in the Mack’s Bayou area is immediately apparent from the 1938 aerial photos, which suggest forest conditions that are present in many parts of Louisiana today. Nevertheless, Ivory-billed Woodpeckers nested there in 1934 and 1935, at minimum, and did so successfully at least once. This fact alone refutes the idea that Ivory-billed Woodpeckers are old growth dependent. Heather informs me that there was an abundance of dead and dying trees on the eastern side of the Mack’s Bayou range, due to a fire caused by logging activities. In any event, the home range Tanner delineated in this primarily second growth area is no larger than the home range he delineated around John’s Bayou, which had more mature forest. In fact, the area he designated as “best” for ivorybills around Mack’s Bayou was slightly smaller than its older equivalent near John’s Bayou.
Tanner knew that a significant portion of the Mack’s Bayou home range was not old growth, since his 1941 map shows “old fields” in the heart of it. He seems to have been unaware of the resurgence of cotton growing during the 1870s and 1880s, so he may have overestimated the age of the forest on that basis. I can’t help but wonder if he glossed over the conditions in the Mack’s Bayou range in part for the sake of protecting the Singer Tract and (as Heather suggested) in part based on what he deemed to be best for the birds from a conservation standpoint, an approach that later ossified into a categorical set of beliefs about old-growth dependence.
As I and others have been arguing for years, extensive forest cover, sufficient dead and dying wood, and enough large trees for roosting and nesting are probably the main requirements, even if old growth or near-old growth conditions are optimal.
I plan to return to the search area in late March and have another post or two in mind in the interim.
Careful examination of bark chips found in conjunction with extensive scaling is one of the key elements in our diagnostic gestalt, but “chips”, a term I’ve been using for years, is both inaccurate and too vague for what we believe is being left behind by Ivory-billed Woodpeckers and for differentiating it from the leavings of other animals. Tanner used “pieces” of bark, ranging “from the size of a “silver dollar to the size of “a man’s hand.” A caption from the National Geographic article on the 1935 Allen and Kellogg expedition that refers to “large chunks of bark”. The existing images of these pieces of bark suggest that chunks is the better term.
It’s important to reiterate that this discussion applies only to live and freshly dead hardwoods. Pines slough bark quickly after death. The process is slower in hardwoods, but as decay progresses, the bark loosens considerably, with the rate of loosening depending on species and environmental conditions. Once the bark has loosened sufficiently, PIWOs can and do scale bark extensively, sometimes leaving behind large chips. In the images that follow (from Allen and Kellogg and Tanner), the bark chips ascribed to ivorybills appear to come from considerably longer dead trees than some of the examples we’ve found, but the images are informative.
The small tree shown above, identified as a “dead gum” by the 1935 expedition, appears to be a hackberry or sugarberry not a gum, and a fairly long dead one; the pieces of bark at the base resemble ones we found beneath hackberries or sugarberries in our old search area, some of which were considerably larger (the one below is the largest).
This colorized slide reveals more about the bark at the base of these pines than the black and white print in Tanner (Plate 9).
There’s also this example, (Plate 10 in Tanner), which appears to be in a considerably more advanced state of decay, and presumably looser, than much of the work we find most interesting. I suspect most of the grubs were placed on the chip for illustrative purposes; the caption “Beetle larvae from beneath bark of Nuttall’s oak” is ambiguous as to where the larvae, which appear to be small Cerambycidae, were actually found.
What I think is most salient in Tanner’s description of bark chips is shape not size. In this regard, it seems important to come up with a more specific set of terms to replace the commonly used “chips”. I’d suggest using chunks and slabs for suspected ivorybill work (although smaller pieces of bark may also be present). Pileated bark removal can involve chips, strips, or flakes, the last when they’re doing the layered scaling discussed here and here. I suspect that squirrels remove hardwood bark primarily or exclusively in strips, and of course, their bark removal on cypresses leaves shredded bark hanging from the trees.
Let’s take a closer look at the differences among pieces of bark we have reason to believe were left by squirrels, those we have reason to believe were left behind by Pileated Woodpeckers, and those we suspect were left behind by Ivory-billed Woodpeckers.
I collected a number of bark chips from the tree we know to have been scaled by a squirrel, and while these were removed before our camera trap revealed the source, there’s strong reason to think they too were left behind by squirrels.
Note the uniformly elongated shape and the ragged appearance at the tops and bottoms of these strips of bark. This is not typical of bark that we infer or know to have been removed by woodpeckers, and it’s consistent with chewing, not scaling. The presumed squirrel strips I collected had the following dimensions:
The downed sweet gum from which they had been removed was a fairly young tree, and the bark is much thinner than on more mature ones. These strips were approximately 1/8″ thick. While this is a very small sample, we suspect (along with Houston from IBWO.net) that approximately 3″ is the upper limit for width when a squirrel is doing the bark removal.
Our research and observations suggest that Pileated Woodpeckers have two strategies for removing tight bark; one involves pecking around the edges until they can gradually pry off small pieces, and the other involves scaling away strips, sometimes in layers. Their physical structure precludes them from doing the extensive, clean scaling of tight bark that Tanner associated with ivorybills.
We suspect that this collection of chips, from a honey locust near a known Pileated nest, reflects the range of what the species is capable of doing on a tight-barked hardwood (and honey locust bark is relatively thin). The upper limit appears to be hand size, with many-quarter sized or smaller.
The following are measurements of some fairly typical suspected Pileated strips from a sweet gum:
The strips shown below, suspected Pileated Woodpecker leavings from a high branch, are on the large end of the spectrum for this category of work. The Peterson Guide is 9.5″ x 6.5″. I can’t rule squirrel out completely for these.
Flakes resemble strips, but they are removed in layers, so that reaching the sapwood is a gradual process. Pileated scaling frequently has this appearance, something that seems frequently to be the case with congeners, including the larger-billed Black Woodpecker (Dryocopus martius).
The chunks and slabs we suspect to be ivorybill work are significantly larger and thicker than strips, flakes and chips, although strips and chips may be present in the mix at the base of suspected feeding trees. Chunks are usually more irregular and varied in size and shape, and both chunks and slabs sometimes have what appear to be strike marks from a broad bill.
I kept one of the chunks scaled from the hickory tree on the homepage, a fairly typical example. It is 8.5″x3.5″ and .375″ thick. (It has undoubtedly lost some of its thickness after drying for over two years.)
The sweet gum chunk with the apparent bill mark Frank is holding is 7.5″x3″ and .25″ thick. On mature, thicker barked trees most or all suspected ivorybill chunks, chips, and slabs will have been removed cleanly, all the way down to the sapwood.
This particular bark “chunk” is intriguing on several levels. We have found that markings many describe as “bill marks” are really truncated galleries between the bark and sapwood. Marks made by woodpecker bills are distinctive, but somewhat subtle, and easily overlooked. This chunk actually has two interesting markings – markings that were left by the animal that removed the bark. The first is near the end of my left thumb – my right index finger is pointing toward it. It is about a quarter inch wide, a bit over a half inch long, and three sixteenths of an inch or so thick. The other is a “V” shaped “notch” at the end of the chunk, near the center of the photo. These places look as if they’ve been struck with a chisel – hard enough to rip the bark away from the sapwood/cambium. This suggests that, even though this bark was very tight, very few strikes were required to loosen and remove it. Granted that these marks are bill strikes, this suggests that the bird removing bark is indeed a powerful animal for its size. Back to Mark.
The two preceding examples are on the smaller side for suspected ivorybill work; in the first, the density, tightness, and grain of hickory bark seem to be a limiting factor on size. Some of the larger examples are shown in the Bark Chip Gallery (as are several of the images shown above). A couple of additional examples of larger slabs are below. In the first, the oak was approximately 8 months dead (leaves attached), and the bark was still tight. (The fractured slab was damaged in transit.)