The calls in question were recorded on remote devices placed by scientists from the Cornell Lab of Ornithology in cypress swamp habitat in both
The claim comes in a paper by Clark Jones and colleagues who, writing in The Wilson Journal of Ornithology (119(2): 259-262), say that the confusion with woodpecker raps may arise because of “close similarities in amplitude ratios, peak-to-peak times between raps, and auditory quality between ARU recordings and wing collisions from a Gadwall”.
One thing has changed since the ‘rediscovery’ was made. The following year, analysis of Ivory-billed Woodpecker DNA from museum specimens led to the suggestion that birds from mainland North America and
* Read Cornell Lab of Ornithology’s discussion of similar sounds here.