Wake Feeding on a Hickory?Posted: March 24, 2017
This is my 100th post on the blog. It has been on hold for a while due to the new developments. There’s another coming soon with more discussion of recent events and the audio Matt obtained with numerous kent-like calls. I’m now even more firmly convinced that IBWOs were the source of those calls, but that’s a topic for the future.
On the weekend of March 4-5, Phil Vanbergen visited the search area and changed out the card on our deployed trail cam. He found that Pileateds had hit the target tree, scaling a single and large strip of bark during one of several visits. The raw sequence and a slowed version by Steve Pagans are immediately below. Phil also found a nearby hickory that had been extensively scaled and some fresh bark chips at the base. Footage of that tree is also below.
When I was in the search area earlier this month, I scrutinized both these trees quite closely, and it appears that the extensive scaling was not recent. Moreover, we did not pass near enough to have seen the scaling when we were in the vicinity in December.
The first of these trees could not be approached on foot, but no large chips were visible at the base, based on careful examination through binoculars. In addition, the strip of bark removed by the Pileated appears to have been exposed on three sides by whatever did the initial scaling. Nevertheless, it took the PIWO over a minute to remove this compromised bark strip.
The chips at the base of the second were either fairly long strips or small chips, many of which had adhering and punky sapwood (first set of images). This contrasts with large chips found at the bases of recently scaled hickories (second set of images).
I now suspect the scaling on these two trees was done no later than early fall of 2016 and quite possibly in late spring, based in part on what we know about the life cycle of the beetles that appear to have been the initial prey species. As discussed in my post on hickory bark, I think this initial work is beyond the physical capacity of Pileated Woodpeckers.
As I was preparing this blog post, Phil asked to see my notes on Tanner’s field notes, and I ran across an observation about which I had forgotten: Tanner observed IBWOs on a partially dead sweet gum, scaling bark in chunks from dollar to hand sized. Shortly after they left a pileated arrived and started knocking off bark. But, also did a little digging. While other scaled hickories monitored for months have shown no signs of subsequent visits by Pileated Woodpeckers, I suspect that what transpired with these two is what Jon Young, author of the outstanding What the Robin Knows calls “wake feeding”, a reference to seabirds following boats for the food they churn up or throw overboard, although the concept applies in a variety of circumstances. This behavior might help to account for the abundance of scaling in our search area relative to other locations in the southeast.
We’re currently targeting three hickories that have multiple old wounds, in fairly close proximity to trees of that species that have been scaled in the past. A fourth tree we had planned to target has fallen. I hope to deploy a fourth trail cam on a wounded or dying hickory in April. This is a very long shot, given the number of hickories in the area and our limited equipment and resources, but it still seems worth a try