Updated with More Pileated Woodpecker Clips: Trail Cam Results and More on a Camera Trap TreePosted: October 29, 2018
The original post from last week is below the updated material. It provides some important background, and I encourage you to read all the way and watch the clips.
A couple of prefatory notes for new readers: first, this discussion pertains to hickories only because the bark of trees in the genus Carya has characteristics that make it much harder to remove than any other type of tree in the southeastern U.S. Second, the video clips are time-lapse composites of images shot at 20 second intervals.
I’ve gone through most of the June-August captures from the deployment discussed in the original post and have found a number of additional examples showing one or two Pileated Woodpeckers foraging on the scaled areas. I’m including those captures and a couple of individual frames that should help illustrate what’s being described.
Pileated visits to the target tree spiked starting on June 17, with two visits on that day, one on June 18, and one on the 20th, 23rd, 24th, 25th, one on July 2, and two on July 3. There were no hits between July 4 and July 10 and no hits between August 2 and August 12. Imagery for July 11-August 1 has yet to be reviewed.
Of the sequences below, the ones from June 17, 18, and 25 are probably the most informative. They suggest that when Pileateds remove hickory bark, even on a tree that is considerably more decayed than some on which we’ve found scaling, they do so by focusing on the scaled edges, and when they do remove bark, they’re more likely to dig through it (as I’ve hypothesized) than to pry it off in flakes.
We have now obtained 22 sequences of Pileated Woodpeckers investigating or foraging on and around extensively scaled hickory boles, the first one dating back to 2013. Some captures involve lone birds and others involve pairs. Duration of the visits ranges from under 1 minute to upwards of 20 minutes. In these captures, Pileated Woodpeckers remove bark in modest quantities and with difficulty, when they remove it at all. They never scale extensively or remove bark in pieces approaching the size of those found under the homepage tree, and there is nothing in the footage obtained that suggests they are capable of doing so. I think this tends to exclude Pileated Woodpecker as the source of the initial work on hickories.
These stills should shed additional light on Pileated Woodpeckers and bark removal.
The additional sequences are below, followed by the text of the original post.
I just returned from Louisiana where I visited both the search area and the location of Joseph Saucier’s sighting last year. There were no possible encounters on this trip and just a little of potential significance ivorybill-wise. I plan to post a trip report within in the next week or so and hope to get to the long-promised evidence post in November. There may be additional posts about trail cam results if anything significant shows up. There are numerous cards to review, and I have a lot going on in a variety of arenas, but I’ll do my best to keep you all updated on a regular basis.
I’ve gone through the card for one of our deployments between August 21-October 20. The June to August card has yet to be reviewed, but these results are informative in their own right, especially in conjunction with the results from April and May, discussed here. I think they tend to support the hypothesis that Pileated Woodpeckers are not responsible for the bulk of the bark removal on live or recently dead hickories and at least indirectly to support the hypothesis that Ivory-billed Woodpeckers are the only creature capable of doing this type of work. (Go here for a discussion of squirrels as a potential source.)
At Tommy Michot’s suggestion, we’re also going to start quantifying our results, including all hits that we note, regardless of what kind of animal is involved. Those results appear at the end of the post.
Like two other current target trees, which are sweet gums not hickories, I selected this one because it had already been scaled (extensively in this case); the remaining (majority of) targets have been chosen in hopes that they will be scaled in the future. For most of the hickories we’ve found, including ones that I’ve watched for extended periods of time, the bulk of the scaling appears to have been done in a single visit.
We’ve found only one example of a tree with truly fresh scaling, the home page tree. That work, found in May 2013, was probably no more than a week old, since the trunk was wet with sap and the tree died soon after. Numerous large chips were found at the base. All other examples appear to have been less recent, and in most instances, flooding appeared to have washed bark chips away.
After reviewing the captures, I was inspired to revisit the history of this particular snag, which Phil Vanbergen found in early March, 2017. It had been extensively scaled at that time, I suspect during the spring or summer of 2016 but possibly the year before. Phil found a few small chips at the base, but given the extent of the scaling, it is safe to assume that the overwhelming majority of the chips associated with the initial work had been washed away in one of the flooding events that had taken place during the intervening months. Phil shot this video of the tree, which shows the work extending from mid-bole up to the point where the crown had broken off; I later found what I believe to have been the crown, and it too had been scaled.
What sets this tree apart, is that there appears to have been a second extensive scaling event between March 2017 and March 2018 when I re-found it. While there had been a couple of floods in the course of the year, one large and a couple of medium-sized chips remained near the base of the snag, but it was apparent that most had been washed away.
We deployed a trail cam on the tree in April, and one of the early frames from that deployment more clearly shows the extent of the second round of scaling, which reaches to near the base of the snag.
A comparison of that frame, one from the beginning of the mostly unreviewed June-August card, and a capture from October 21 of this year shows how little bark has been removed by Pileated and other woodpeckers over the course of just under six months, with modest quantities removed from the bole, as indicated by the arrows.
Pileated Woodpeckers appeared in two captures between late August and late October, a far lower rate than in April and May. The first capture, from September 24, involved one bird, which spent several minutes on the target tree and did little additional damage. The other, from October 5 involved two birds and was fleeting but cool to see. The time lapse clip and the three captures are below
Pileated Woodpeckers are abundant in the area, but we have yet to obtain any evidence that they can remove large chunks of bark from the boles of live or recently dead hickories and scale them rapidly and extensively; indeed, all the evidence obtained thus far is that they remove bark in small pieces, slowly and inefficiently.
Past observations suggest that the peak period for scaling of these hickories is between May and October. This appears to be the time frame when Hesperandra polita, the heartwood dwelling Cermabycid identified as infesting one of our scaled hickories, are likeliest to be found under the bark, as larvae and adults, or close to the bark layer in pupation chambers. The adults shown below were collected from under bark on June 28, 2013.
In the case of this snag, at least, Pileated Woodpeckers removed little bark during the probable peak scaling period. The other side of the tree remains unscaled. In addition, we’ve found this work infrequently over the years, and the scaling on the lower part of this tree is the only new example of this kind of foraging sign found in the past year. All of this points to something other than Pileated Woodpecker, and I would suggest something rare, as the source of the scaling.
Regarding the hits over the course of the deployment, I’m counting a “hit” as the appearance of an animal in a frame or series of frames, including interrupted series in which the animal reappears after a break of a minute or two. Impressionistically, this deployment is considerably more active than some. Even so, there were no hits on 17 of 62 days.
The most frequent hits were lizards (mostly on the target tree): 46 hits.
Passerines, including Hooded Warblers, Carolina Wrens, and Cardinals, were next with 24 hits, followed closely by squirrels with 22.
Woodpeckers followed – 2 Pileated hits, one involving two birds, one Downy and one probable Yellow-bellied Sapsucker toward the end of the deployment.
There were two hits each for beaver, deer, and moth or butterfly (one likely a luna moth).
Finally, there was one apparent Barred Owl and only one hog, which was surprising given their abundance in the area.
Stay tuned for the trip report . . .