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

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

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

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

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

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

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

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

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

 

 

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