Fiddler crabs...abound on the island and are a popular food source.... Large male fiddler crabs may grab the ibises' bill. When this occurs the bird gives several billshakes until the crab relinquishes his hold.
Reproductive Behavior and Ecology of the White Ibis, [dissertation] by Thomas James Rudegeair (1975). Click here to read the book online, or download it free, from the Internet Archive.
Posted today on Alphadello.