In late 2011, I visited the Museum of Natural History at Harvard and took some iPhone photos of the Ivory-billed Woodpecker nest that’s on display there. In reviewing the pictures of cavities I took last week in Louisiana, I was struck by the similarity in appearance, especially between the Harvard cavity and the cavity in the stack, the most significant difference is in orientation; one angles left and the other right. I’ve cropped and zoomed the Louisiana cavity, while boosting the contrast and details, and I’ve flipped the Harvard cavity so the orientation is the same.  

 

The Louisiana cavity could, of course, have been gnawed by squirrels, but the similarity is intriguing.

Edited to add: while I believe there is a type of feeding sign that is diagnostic for IBWO, cavities are another matter. In my view, ivorybill-ish cavities only become interesting when associated with other indicators, especially feeding sign.