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Cavity Comparison

In late 2011, I visited the Museum of Natural History at Harvard and took some iPhone photos of the Ivory-billed Woodpecker nest that’s on display there. In reviewing the pictures of cavities I took last week in Louisiana, I was struck by the similarity in appearance, especially between the Harvard cavity and the cavity in the stack, the most significant difference is in orientation; one angles left and the other right. I’ve cropped and zoomed the Louisiana cavity, while boosting the contrast and details, and I’ve flipped the Harvard cavity so the orientation is the same.  ImageImage

 

The Louisiana cavity could, of course, have been gnawed by squirrels, but the similarity is intriguing.

Edited to add: while I believe there is a type of feeding sign that is diagnostic for IBWO, cavities are another matter. In my view, ivorybill-ish cavities only become interesting when associated with other indicators, especially feeding sign.
 

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Trip Report: May 8-11, 2014

On Thursday and Friday, Patricia Johnson (my wife) and I visited the Project Coyote search area. On Saturday we were joined by Frank Wiley and Steve Pagans, and on Sunday, Frank and I visited one area and Steve another. Weather conditions were generally good, with clear skies and temperatures in the 80s, except on Friday when rain limited our field time to a couple of hours.

Thursday, Patricia and I visited the southern search area – where we’ve spent most of our time, have found concentrations of scaling, including two of the heavily heavily scaled hickories discussed in previous posts, and have had the most contacts over the past couple of years. We did not see or hear anything of interest and found no fresh feeding sign, except for an oddly excavated live maple, unusual but not what I consider highly suggestive. I suspect this to be Pileated Woodpecker work but have included a photograph and a detail nonetheless.

Unusual excavation on live maple

Unusual excavation on live maple

Detail of excavation on live maple

Detail of excavation on live maple

One nice find was a large canebrake rattlesnake, as big around as my forearm.

Canebrake

The weather on Friday was bad, with moderate to heavy rain in the early morning, sporadic rain a little later, and steadier rain toward noon. We did what we could, but conditions were such that it wasn’t much. We visited another area in the southern sector where we’ve found concentrations of feeding sign over the years and where there have been some putative encounters, both visual and auditory. Patricia and I found an impressively and recently scaled fallen sweet gum approximately 20 yards east of a gravel road. The tree was not long dead and had fallen across a bayou either before or shortly after succumbing, undoubtedly within the last four months. Close examination revealed that some of the upper branches had been scaled well before the tree fell, but most of the work was fairly fresh; some of the bark chips were quite large, considerably larger than Tanner’s ‘between the size of a silver dollar and a man’s hand’; the bark ranged from moderately tight (difficult to pull off by hand) to tight (impossible to pull off by hand).

MoreSGDowned

Photo of Frank Wiley and Mark Michaels by Patricia Johnson included to provide a sense of scale.

Photo of Frank Wiley and Mark Michaels by Patricia Johnson included to provide a sense of scale.

Detail of scaling on downed sweet gum

Detail of scaling on downed sweet gum

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Inch long larvae found under bark of downed sweet gum. Photos by Patricia Johnson

Inch long larvae found under bark of downed sweet gum. Photos by Patricia Johnson

We did not collect the beetle larvae found under the bark and do not know whether they are identifiable. Edited to add: the larvae were found under the loosest section of bark; an entomologist suggested they are likely some kind of darkling beetle (Tenebrionidae). One insect species has been identified for us, the Bess Beetle or horned passalus (Odontotaenius disjunctus). This insect appears to be abundant throughout the search area. This is the species Audubon depicted in his iconic image, which inaccurately shows this ground and stump-dwelling insect on a high branch. The Birds of North America species account for the Ivory-billed Woodpecker includes this passage:

“Although the favored food of Ivory-billeds appears to have been the large larvae of some long-horned beetles (Cerambycidae; probably because of their size and hence volume of nutrients per larva), they have also been reported attracted to trees killed during what sounds like southern pine beetle (Dendroctonus frontalis; Scolytidae) outbreaks. Reports of Ivory-billeds foraging on downed wood suggests the probability that they also readily took the large larvae of other beetles, such as the horned passalus (Popilius disjunctus; Passalidae).”

Horned Passalid

Horned passalus or Bess Beetle

On Saturday, Steve Pagans joined us, and we went into a more northerly area. This is one of the easiest access points for getting into some very mature, predominantly sweet gum forest. Upon reaching the bottom, we worked our way south to territory we had not visited before. We came upon an area that is often wet and found a concentration of old cavities and a good deal of old scaling but no recent feeding sign. The live sweet gum in the first image was probably 4.5′ dbh. The crown has blown off within the past few years, and there is an old cavity just beneath the blowdown, approximately 50′ up (second photo). Although all the sign in this area is clearly a few years old, we are encouraged because this is the first real concentration of large cavities we’ve been able to find. There’s very little indication of human activity in this sector, no shotgun shells or litter, and only two or three flagged hunting routes, well north of the cavity cluster. Adjacent areas are even less accessible.

Huge sweet gum. Still alive although crown had fallen. Old cavity was just below the break-off point, approximately 50' up.

Patricia Johnson and huge sweet gum, alive although the crown fell some time ago. Old cavity was just below the break-off point, approximately 50′ up.

Old cavity in de-crowned sweet gum.

Old cavity in de-crowned sweet gum.

Cavity on left side of dead stub, live sweet gum

Cavity on left side of dead stub, live sweet gum

Old cavities in dead sweet gum.

Old cavities in dead sweet gum.

Example of old scaling and other woodpecker work on snags in the vicinity of a cavity cluster

Example of old scaling and other woodpecker work on snags in the vicinity of a cavity cluster

On Sunday, Steve focused on one area in the southern section, and Frank and I went into the other. We went a little farther north than we’d been before and found the habitat to be of lower quality, more recently logged and more even aged, with less standing dead wood. The amount of woodpecker foraging sign was not insubstantial, but there was nothing remotely suggestive of IBWO. Steve did not find anything other than the heavily scaled tree shown above, but his movements were somewhat limited because a new beaver dam has altered conditions and made access more difficult.

An off-topic note that should be of interest to anyone who spends time outdoors during warm weather: biting insects and ticks are abundant at this time of year. Last season, I contracted a tick-borne illness (Ehrlichiosis) and was covered in mosquito bites. This year, I wore Gamehide tick-proof clothing, which also repels biting insects. I had no tick or chigger bites and was barely bothered by mosquitoes.

I expect to return to the search area in late fall or early winter and to devote more time to searching next season.


A Bark Chip, BIll Strikes, and Specimens: Four Images from 2010

For those who missed them, I thought I’d repost these images from 2010. The bark chip is from the old Project Coyote search area.

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PWIO bill chip


An Unpublished Image from 2009 and Some Reflections on Remote Cameras

I wanted to respond a recent post from Cyberthrush and thought it would be better to do so here rather than as a comment on his blog, since I will include few photographs.

Cyberthrush wrote:

As a sidenote, there is BTW, one paradox that DOES concern me: it’s one thing for humans to have difficulty encountering IBWOs, it’s another for non-thinking, non-tiring, 24-hour-working cameras to fail to encounter the bird. Despite 1000’s of hours of automatic, remote camera-recording (literally millions of picture frames) from habitat, cavities, and foraging sites that appeared favorable, we have utterly failed, over years, to detect a SINGLE Ivory-billed Woodpecker — even though these birds must, to exist at all, regularly forage, roost, fly about, breed, etc.  This is the single most devastating result of the entire USFWS/Cornell search — having said that, I’ll quickly add that the cameras (which often malfunctioned, BTW) were used in relatively few areas — compared to all the suitable habitat available.  Still, cameras were placed where, following much study, the best chance of capturing an Ivory-bill on tape was anticipated — either Ivory-bills were not there, despite prior alleged evidence that they were, or we humans are bumblingly, mind-blowingly incompetent at ever understanding/predicting this species’ behavior (personally, I’m voting for the gross friggin’ human incompetence option, but I could be wrong, maybe they aren’t there)].

With regard to the failure of remote cameras to detect an Ivory-billed Woodpecker, over the years Project Coyote has gotten several Reconyx images that are suggestive but are not of sufficient quality to be conclusive. We published two images from the old search area on the old website and are reposting the more intriguing of the two below (we disagree about the other.) We’ve never shared a third image publicly, although we agree that it is suggestive. We are doing so now to illustrate just how limited the cameras are. Both pictures were taken at fairly close range, no more than 100 feet from the subject, and we have teased as much detail out of them as we can. In both cases, better camera technology would probably have made it possible to identify the subjects with certainty. These cameras were designed for taking pictures of terrestrial mammals at close range, and their limitations become very evident when birds are the target.

 

Reconyx image taken August 11th 2009. Possible Ivory-billed Woodpecker is just below the major fork in the center tree. A squirrel can also bee seen near the suspected roost hole, higher on the trunk.

Reconyx image taken August 11th 2009. Original image has been doubled to improve resolution but is otherwise unaltered. Possible Ivory-billed Woodpecker is just below the major fork in the center tree. A squirrel is also discernible near the suspected roost hole, higher on the trunk.

 

Detail of August 2009 image. It has been suggested that the red in the crest is an artifact, but artifact or not, the quantity of black in the crest appears inconsistent with Pileated Woodpecker. What may be part of the white saddle is visible on the lower left.

Detail of August 2009 image, enhanced in Photoshop to the best of my ability. It has been suggested that the red in the crest is an artifact, but artifact or not, the quantity of black in the crest appears inconsistent with Pileated Woodpecker. What may be part of the white saddle is visible on the lower left of the bird, a creamy white which contrasts with the bluish white of the backlighting just below it.

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Reconyx image taken November 30, 2011 and details showing suspected Ivory-billed Woodpecker, possibly a female. Red crests are visible on Pileated Woodpeckers in Reconyx images captured under similar conditions and at similar distances. The bird is only present in a single frame. I had a sighting at this spot one week before.

 

As Cyberthrush observed, the cameras are prone to malfunction, and even when they do operate properly, they can only shoot an image every 20-30 seconds. This means they miss a good deal of avian activity. We have examined many thousand Reconyx images over the years, and the number of sequences showing any woodpecker for more than a single frame is very small. The sequence showing a PIWO and a HAWO (scroll down), captured last spring is unique. Getting good Reconyx images of common species is considerably more difficult than it seems.

 

There are several additional issues. First, when it comes to the kind of bark scaling we think is associated with Ivory-billed Woodpeckers, there are no return visits for several months after the feeding sign has been found. In our search area, a tree scaled in March had additional work done on it in May. In the new area, we have had no clear evidence of return visits to the trees scaled last year, and in one instance – involving higher branch, more Tanner-like scaling – the work appeared to have been done approximately a year apart. Not leaving cameras in place for long enough may have led to missed opportunities.

 

I disagree with Cyberthrush’s “gross friggin’ human incompetence option”, but the human element is quite likely a factor. I understand that on at least some of the official searches, no effort was made to camouflage the cameras, something we think is very important. In addition, as I pointed out in a recent comment on CT’s blog, J.J. Kuhn (not James T. Tanner) was the last person who knew how to find ivorybills reliably. It’s pretty clear that feeding sign was a key component. The issue here isn’t competence; it’s the lack of sufficient, reliable information.

 

Some people are convinced there’s no way to distinguish IBWO from PIWO work (and I agree that’s true most of the time.) But I believe more attention could have been paid to the existing images from the Singer Tract and to the work of other Campephilus woodpeckers. I’m also not aware of much importance being attached to bark chips, despite the fact that they’re mentioned in the literature. It took me several years of obsessing over this subject to arrive at a working hypothesis. But even if I’m correct, that doesn’t address the need to have a camera in the right place at the right time.

 

I’ll be making a brief visit to our search area next week and will likely post an update after I return.