Documentation of bill clapping in Hooded Crow Corvus cornix

Cover photo: Hooded Crow Corvus cornix. Photo: Terje Lislevand. Non-vocal sounds made by rapid closing of the bill are well known among many bird species, including several corvids. However, this is the first documentation of bill clapping by a Hooded Crow Corvus cornix during aggressive encounters with a conspecific. The aggression level was low, and the bill clapping was accompanied by a weak rolling ‘r’ sound.