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Bark: An Exegesis

Introduction:

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

Discussion:

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

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

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Pileated Woodpecker feeding sign on a slender limb

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Conclusion:

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

Lagniappe:

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

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References Cited:

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

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

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

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

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

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

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

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

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

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

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

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

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Trip Report: January 25-30, 2018

From January 25-30, Stephen Pagans and Erik Hendrickson and I searched in the vicinity of Joseph Saucier’s October sighting. I’ll begin with a day-by-day log accompanied by some photographs, followed by a discussion of our observations and what they may imply, with photographs from our last day in the field. I’ll end with some or Erik’s photos. They help convey the experience of being in the field more effectively than most of mine. This is an image heavy post, so I hope you’ll take the time to look at and enjoy the pictures.

We had no possible sightings or auditory encounters and devoted most of our time to surveying. We did a few ADK series, sometimes followed by Erik’s tooting on a baritone sax mouthpiece, the best imitation of the Singer Tract kents I’ve heard.

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Mark Michaels in Background, Double Knocking with Cypress Dowels. Stephen Pagans at right.  Photo by Erik Hendrickson

There were no apparent responses. Scaling consistent with what’s described for ivorybill was abundant in most areas visited. Large and possibly suggestive cavities were also relatively easy to find. This contrasts with the primary search area, where cavities of any size are difficult to locate. This may be due to the ~30% lower canopy at this location.

We covered between 4 and 5 miles most days. For the most part, we tried to avoid repeating the same tracks. We saw substantial flocks of Rusty Blackbirds on a couple of occasions. We didn’t encounter many mammals – an armadillo, a rabbit, and some glimpses of hogs. We found little beaver sign but didn’t get into the area where we understand beavers are most abundant.

 

We spent the 25th and 26th in the immediate vicinity of the sighting. The habitat in this area is extensive and impressive, as it was in most places we visited. We found considerably more scaling on this trip than on the last one, as well as more cavities. As mentioned previously, the cypress in this area was not heavily logged, so many large trees remain, not all of them as obviously undesirable as the ones shown.

 

 

Suggestive Scaling and Cavities Found January 25 and 26, 2018. Scaled tree species include sweet gum, honey locust, and sugarberry.

The 27th was a rainout. We spent that morning birding from the road around a nearby lake. I went to Alexandria for a brief visit to the annual meeting of the Louisiana Ornithological Society.

On the 28th, which was cloudy and drizzly, we went to a different nearby location. Again, we found some decent or better habitat, a good deal of bark scaling, and other indications of woodpecker activity, including a cavity resembling an ivorybill roost in an unpublished image from the Singer Tract. By late morning, we reached an area of much younger forest, so we turned back.

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One of the cavities strongly resembled one of Tanner’s unpublished images of an ivorybill roost.

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Ivory-billed Woodpecker Roost in Dead Ash, Courtesy of the Division of Rare and Manuscript Collections, Cornell University Library

On the 29th, we visited a different area, also nearby. The habitat was again impressive, but we only found one recently and extensively scaled sweet gum with very large chips at the base and an unusual bit of excavation on the edge of a scaled part of the trunk. An area that we could not reach appeared to contain even more mature forest and probably merits a visit in future.

 

On the 30th, we found another entry point. About two miles into the woods, we found more sweet gum scaling than I’ve seen in a single day, approaching or surpassing the quantity found during the most productive weeks in our main search area. Again, we found a number of potentially interesting cavities, new and old, including one in a cottonwood snag that had been extensively stripped of bark, this along the edge of an old logging road. We guessed that this concentration of scaling was in a patch of around 100 acres, but we were unable to explore it fully, so we can’t be sure how extensive it might be.

With the passage of time, I’m even more struck by the extraordinary nature of what we found on the 30th.

Some Comments on the Scaling and Cavities

As noted, I was impressed by the abundance of scaling found in the vicinity of the sighting and even more so in the concentration found on the 30th. The latter was truly unprecedented in my experience. As was the case in Tanner’s day, sweet gums with dying crowns are the primary target. The work found is consistent with that shown and described by Tanner. More on sweet gums below.

Additional work was found on honey locust, sugarberry, American elm, and cottonwood. Bark on all of these species (possibly excluding cottonwood which has high adhesion values and bark strength) becomes easy to remove fairly rapidly after death, and none of the scaling approached what I’d consider possibly diagnostic for ivorybill (again perhaps excluding the cottonwood). Still, the quantity of it may be significant.

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Scaled cottonwood snag with large cavity. While this snag is longer dead than some, the scaling is not recent. Cottonwood bark shares properties with hickory and probably adheres more tightly for longer than the bark of many other species, including sweet gum.

We found no scaling on oaks. (The same has been true in the main search area, except in 2012-2013.) Steve suggested this may be due to the fact that the forest is relatively young, so the oaks are still healthy.

The sweet gum scaling was mostly found in clusters, with the notable exception of the single tree found on the 29th. This may be due to the pattern of sweet gum die-off, but we did visit areas with unscaled, dead and dying gums.

The sweet gum scaling ranged from old to very fresh, probably a year or two to a day or two. All trees were recently dead, with twigs and sometimes gum balls and leaves attached. Much of it was extensive, involving larger limbs and sometimes main trunks. Bark chips ranged from very small and consistent with what I’d expect for PIWO, to larger strips that I’ve also tended to ascribe to PIWO, to much larger chunks that I think are considerably less likely to be Pileated.

 

Regarding the sweet gum scaling in general, I have only found a similar quantity and quality of scaling on this species in our main search area and at this location. Scaling in the old Project Coyote search area was on a wider variety of species, with only a little on sweet gums. I never saw anything like this in over two weeks in Congaree or in briefer visits to other areas. The Carlisles, who are searching in the Pascagoula area, have found at most a similar looking example or two over several seasons, and Paul McCaslin, one of the earliest Project Coyote team members recently sent me a note reading: “I am still amazed, every time, at the scaling pics you send from the tops of those sweetgum trees. I am an ISA Certified Arborist and spend a lot of time looking up at trees and I NEVER see anything even close up on my neck of the woods.”

To cut to the chase – if Ivory-billed Woodpeckers are not present and this work is being done by Pileateds, then I don’t think either quantity or apparent quality of bark scaling on sweet gums can be treated as a reliable indicator of ivorybill presence.

 

With regard to other tree species, I still think that the work on hickories found in the main search area is likely diagnostic. Work on live or very recently dead honey locusts (like the one in some of the old trail cam photos), cottonwoods, sugarberries (one example found in in the old search area) and oaks (one or two examples found in the old search area and several found in the new one in 2012-2013) may be as well.  Though I’ve grown increasingly cautious about sweet gums, the concepts discussed in the post entitled Bark: An Exegesis still hold.

Some Closing Thoughts

Though I have now spent multiple days in this area without any possible ivorybill contacts, I remain very impressed by the habitat and continue to think the initial report is highly credible. The scaling is abundant and suggestive, as are the cavities. However, the extensiveness is daunting, and I don’t see a way for a small, self-funded group to search it effectively. In the current search area, we have the benefits of compactness and known, readily accessible locations where there have been frequent possible contacts over a period of years. I think there’s a good possibility that ivorybills are present in the vicinity of Joseph’s sighting, and there’s sufficient habitat to make detection very difficult. I’m at a loss as to how to find them (without an infusion of J.J. Kuhn’s skills as a ‘woodsman’), if indeed any are there.

Here are some of Erik’s photos for your enjoyment.

 

 


Trip Report: December 27, 2017 – January 1, 2018 and Some New Year’s Appreciations

I returned to the main Project Coyote search area where I spent December 27-January 1. I was joined by two new team members – Erik Hendrickson, an excellent birder and retired National Park Service engineer who had an ivorybill sighting in Arkansas back in 2005, and Jay Tischendorf, a veterinarian with a long and adventure-filled background as a field biologist. Erik lives in Colorado, so he may not be able to visit often, but Jay is much closer. I hope that both of them will be able to return and bring their considerable skills to the effort.

Stephen Pagans, who has been with Project Coyote since 2012, was in the area for the duration. Steve is a retired forester, avid birder with a great ear, and an outstanding photographer. This portrait of a feral hog (more on hogs later), which I think is award-worthy, is just one example of his work.

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Feral Hog Photographed by Stephen Pagans

Tom Foti made it down from Arkansas for a day. Spending time in the woods with Tom, whose knowledge of bottomland forests is second to none, is always an education. On this trip, Tom pointed out that I’d been mistaken about the hickories in the search area. I believed that they were all bitternut hickories (Carya cordiformis), except for a very few shagbarks (Carya ovata), but it turns out that many, perhaps the majority, are in fact pignut hickories (Carya glabra). One of these, shown below, has a DBH of 42″ and may be a state champion. Tom also identified a nutmeg hickory (Carya myristicaeformis), an uncommon species that may not have been previously recorded in the parish.

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Jay Tischendorf beside a potential champion pignut hickory

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Nutmeg Hickory Photo by Erik Hendrickson.

Having such great companions for the week caused me to look back at the past year, with its terrible low points – the losses of Frank and Bill Pulliam – and high points, particularly the March recordings, which I think are among the strongest evidence of ivorybill persistence obtained to date, and to appreciate my friends, collaborators, and outside advisors. Although I’ve been the public face of Project Coyote for years (Frank wanted it that way), this has always been a team effort, although the composition of the group has shifted over time. While it would be cumbersome to name everyone involved and some frequent advisers prefer to remain anonymous, there are several, in addition to those mentioned above, whom I’d like to acknowledge publicly.

On more than one occasion over the years, Bob Ford has lifted my spirits when they most needed lifting. When I talked to Bob shortly before Frank’s death, I was despondent. I knew Frank’s prognosis was not good and was having doubts about carrying on. Bob helped me see a way forward, reminding me that the search area is important, ivorybills or no ivorybills, and that I’d done meaningful work related to its ecology in general.

Matt Courtman, who had some involvement early on and had known Frank for several years, reached out shortly after Frank died, giving me much needed moral and intellectual support and breathing new life into Project Coyote. In one of those odd coincidences, Matt’s New York relatives knew and did business with my father decades ago.

Philip Vanbergen, the youngest among us, had the presence of mind to turn on his recording device on March 11 and capture a couple of calls, setting the stage for his and Matt’s return on the 15th when the much longer recordings were made. Phil has also been responsible for our trail cams since 2016. His energy, enthusiasm, and interest in the natural history of the area are invaluable.

Peggy Shrum’s ideas, background studying raptors in the Peruvian rainforest (a considerably more challenging environment), and familiarity with tropical Campephilus double knocks are great assets. Peggy has made the long trip from South Carolina to participate several times, and it’s always a pleasure to have her along.

Tommy Michot and Wylie Barrow from Lafayette have also been great sources of support. Though Tommy is a retired biologist with a Ph.D, I admire his youthful enthusiasm, open-mindedness, enjoyment of the woods, and his sense of humor. To top it off, he’s also an accomplished traditional Cajun musician from an illustrious musical family.  Wylie and Tommy have known each other for years, and while Wylie has seldom been able to make it into the field, his careful, scientific approach and probing questions help keep me on track. While I skipped it on this most recent trip, the lunches I have with Wylie and Tommy (and sometimes Phil) in Lafayette on the way home invariably help me absorb and evaluate whatever I’ve observed or experienced while searching.

Professor Fredrik Bryntesson has been a great online friend and supporter. He has shared details from his research into some arcane aspects of ivorybill history, some of which have found their way onto the blog. I hope we get to meet in person and that he will be able to visit our search area sometime soon.

Finally, Patricia Johnson, my wife – Patricia comes along from time to time, holds down the house when she stays at home. Her moral and morale support sustain me.

Though 2017 was difficult, I’m grateful to be surrounded by such great collaborators. I’m hoping for more highs and fewer lows in the year ahead . . . Without further ado, here’s the trip report. As with the previous one, I’ve opted not to do a day-by-day log. There’s not all that much to report.

The weather this trip ranged from cloudy, dreary, and damp to bitterly cold; there was little sunshine, except on January 1st, and avian activity was generally low throughout. Woodpeckers, except for Red-headeds, were mostly quieter and less active than usual. Nevertheless, on at least one day, we saw or heard all seven species (ivorybill excluded) that are found in the area at this time of year.

Birds may not have been very active, but the hogs certainly were. We saw upwards of 15-20 on a couple of days, and signs of their rooting were everywhere. Their numbers seem to have increased considerably since 2012, despite the presence of at least a few dedicated hunters in the area. We ran across these newborn hogs and assumed their mother had been shot. Their cute appearance belies their destructive potential should they survive. IMGP5639

We did not have any possible ivorybill encounters and found little recent bark scaling, except on two or three sweet gums,  some extensive work on a pine, and a small patch on a cypress. Some commentary below the images.

Phil solved the problem with the trail cams, and we now have three deployed on hickories – two that have lost their tops and one that is in obvious decline. We’ll deploy the fourth in the spring when it will be easier to locate unhealthy trees. Given what we’ve observed and the life cycle of the beetles involved, I think scaling on hickories is most likely to take place between mid to late spring and fall.

IMGP5580IMGP5583Fresh scaling on the bole and branches of a recently uprooted sweet gum. Some of the bark chips were large and consistent with what I would expect for Ivory-billed Woodpecker.

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Extensive, recent scaling on medium and large sweet gum limbs.

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Recent scaling on large sweet gum limb. Photo by Stephen Pagans

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Extensive scaling on a freshly dead pine top (needles still attached).

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Scaling, targeted woodpecker dig, and insect galleries on a beaver-killed cypress.

With regard to the sweet gum scaling, it is far and away the most abundant form of this work we’ve found, and this has been true year after year. It is considerably more common in the Project Coyote search area than in other places I’ve visited or than in the Pascagoula, based on the Carlisles’ efforts there. It also matches the work described by Tanner as being typical of ivorybill, but as discussed in my post entitled Bark: An Exegesis, sweet gum bark is relatively easy to scale, making it more difficult to exclude Pileated Woodpecker. As an aside, I’m puzzled by the fact that we found a good deal of scaling on oaks in 2012-2013 and have seen virtually none since then.

While I’ve written previously that I think pine has no potential for being a diagnostic because it is easily scaled, the example above impressed me for its extensiveness and the fact that the presence of needles suggests the tree died very recently. Lighting conditions in the field were so poor that it was impossible to see that scattered patches of bark remained. This only became apparent when I brightened the photographs. Even so, the extensiveness so soon after death remains impressive.

I’ve included the beaver-killed cypress scaling here not because I think it’s likely ivorybill work; it could be, but the bark was loose, and the scaled area, while contiguous, covered only a modest percentage of the bole. What may be significant is the presence of insect work of a kind that is suggestive of suitable ivorybill prey. Tanner thought that cypress-tupelo swamps were poor habitats for the ivorybill, presumably because both are long-lived and relatively insect-resistant species and perhaps because he rarely ran across large scale deadenings of those species. The example shown here leads me to wonder about this assumption, particularly in places where beavers are present or other disturbances occur; fire, to which water tupelos are apparently vulnerable, for example. While Allen and Kellogg reported that Florida ivorybills nested in cypress and fed nearby on fire damaged pines, I think it’s possible that food sources would be sufficient in cypress-tupelo swamps under certain conditions. This relates, at least indirectly, to issues that have been addressed in the “Bits and Pieces” series. Stay tuned for the final installment.


:)