RESPONSIVENESS OF ELF OWLS TO CONSPECIFIC AND GREAT HORNED OWL CALLS

Abstract

A common assumption made when conducting broadcast surveys for owls is that vocalizations of larger owls reduce the responsiveness of smaller owls. We tested this assumption by comparing the responsiveness of Elf Owls (Micrathene whitneyi) exposed to the taped calls of conspecifics and to imitations of Great Horned Owls (Bubo virginianus). Elf Owls were more responsive to conspecific calls during courtship and incubation, but less responsive during the nestling stage, than they were to Great Horned Owl calls. This was because responsiveness to conspecific calls decreased through the nesting season, but responsiveness to Great Horned Owl calls was consistent throughout the nesting season. Singing Elf Owls switched from song to scold vocalizations more frequently after hearing a Great Horned Owl call (83.3%) than when hearing a conspecific call (33.3%). The responsiveness of Elf Owls to Great Horned Owl calls may benefit studies conducted throughout the breeding season.