According to Tanner, Ivory-billed Woodpeckers, “When feeding by knocking off bark . . . hit sidewise blows from both directions, and often pry and knock off the pieces of bark with a flick of the bill”. He wrote that the bark chips produced in this manner range from the “size of a silver dollar to the size of a man’s hand” when the bark is tight; looser bark “is detached in even larger pieces.” According to a photo caption in Arthur Allen’s 1937 National Geographic account of the Allen and Kellogg expedition, “To locate a nest, Dr. Allen searched for the large chunks of bark which the bird strips from trees.”
There are a couple of clear images of bark chips left behind by Ivory-billed Woodpeckers, and both of them are considerably larger than what Tanner described. These appear to be from trees where the bark had loosened or fractured.
We have found many similar chips beneath scaled trees, in both of our search areas. As discussed in this post, chips left by Pileated Woodpeckers (which are anatomically less well-suited to removing bark) tend to be smaller, thinner, and less dense, and Pileateds often scale in layers rather than removing bark all the way down to the sapwood with a single strike. Many of the chips we’ve found appear to have bill marks that are consistent with a powerful blow from a chisel shaped bill. As Frank puts it, think of the difference between a chisel (ivorybill) and an icepick (pileated).
The bark chips shown here are from dying trees, recently dead, tight-barked snags, or dead parts of live trees – sweet gums, hickories, oaks, honey locusts, and hackberries. Most were in a very early decay stage, probably earlier than Tanner’s plate 10. Many of these images appear in various posts on this blog, but I thought there might be some value in aggregating them, without further commentary.