Differential responsiveness of young ring-billed gulls and herring gulls to adult vocalizations of their own and other species

Abstract

Approach and vocal responses to adult mew calls of both species were measured in the laboratory for 40 parentally naive ring-billed and 15 herring gull chicks. A separate sample of 20 ring-billed gulls were tested with mew calls of their own species and those of the black-billed gull. Posthatch responsiveness of 14 herring gulls stimulated with herring gull mew calls during the pipped egg stage was also examinedApproach and vocal responses were positively correlated. For ring-billed gulls, both occurred most often to the call of their own species. Herring gulls also responded more to the ring-billed than to the herring gull calls. Embryonic stimulation of herring gulls enhanced posthatch responses to calls of both species, but did not reverse the preference for ring-billed gull mew calls.The greater responsiveness of young ring-billed gulls to calls of their own species is similar to results for several precocial species, but the preferential responsiveness of herring gulls for the call of another species provides an apprent exception. Some functional and developmental implications of these species differences are discussed.