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Wake Feeding on a Hickory?

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

 

 

 

 

 

 

 

Pileated Hickory Bark Snip

 

 

 

 

 

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Numerous Kent-like Calls Recorded on March 11 and 15, 2017

Kudos to Phil Vanbergen for being the first to point out these calls and for having the presence of mind to capture them initially and to capture so many on Wednesday. He’s back in the field today and perhaps tomorrow. Steve Pagans will be in the area this weekend as well.

Update: March 18, Phil reports there were no suspicious sounds in the area this morning.

This post will be heavy on media and short on commentary. My usual trip report and additional discussion of this and other new developments will follow within a week or so.

On the afternoon of Saturday, March 11, Matt Courtman (an outstanding, lifetime birder) Phil, and I were in the search area, and Phil called our attention to some kent-like calls. He was able to capture two of them on his handheld recorder. I’m posting both an excerpt that highlights the calls and the entire clip to provide more context and show our reactions, including my talking over the second one.

It is much easier to hear the calls through headphones or ear buds, but some of them are even audible through an iPhone.

On the morning of March 12, Steve Pagans, Matt, and I heard possible calls and knocks at the same location.

Phil recorded the following clips on the morning of March 15, again at the same location. Matt was present and may have additional recorded sounds. If so, they’ll be included in a follow-up post. The first group of clips contains extracted highlights, including one possible single knock in reaction to an ADK. Next are the unedited originals, containing additional calls. The calls began at around 7:20 am and continued until late morning.

Some additional comments:

A few of the calls Phil recorded are higher pitched and seem to resemble the ones I captured in March 2013. These are harder to hear. Edited to add: On review, these higher pitched sounds appear to be tree squeaks; I’m confident that the March 2013 calls were not.

For those who want to run sonograms, I’d suggest the best comparison would be to Cornell’s recorded playback of the Singer Tract calls at 145 yards.

Edited to add: Here are two sonograms I’ve been able to pull using free sonogram software. I’m no expert on bioacoustics or sonogram analysis, but these appear to be strikingly similar to the Singer Tract recordings in terms of fundamental frequencies and harmonic structure, with the second harmonic stronger than the first. The calls are at just before 5 seconds in the first image (from the Saturday), and before 2, 3, and 4 seconds in the second.

Audio TrimmedScreen Shot 2017-03-16 at 4.57.17 AM

For those who want to compare the clips with the Singer Tract recordings and are unfamiliar with them, you can hear them all here.

And here are the full clips for the hardcore among you.