Vocal Communication in Otariids and Odobenids

Abstract

Otariids and Odobenids produce copious vocal signals in air and/or under water. The two main behavioral contexts in which they produce vocalizations are during mother-young interactions and male breeding vocal behavior. The social bond between mother and her young is very strong in both otariids and walrus, and their vocal exchanges start at birth. Individual vocal stereotypy has been found in both mothers and pups, and individual vocal recognition seems to be mutual in most otariids species, with the onset of individual identification being established soon after parturition in females, and within 2 weeks of birth in pups. The individual vocal signatures deciphered for mothers and pups involve temporal and spectral features, allowing for a large array of possible vocal ‘codes’ that can be used to help avoid confusion among individuals. Otariids and walrus males show greater vocal diversity than females, and produce calls both in air and under water, with significant individual vocal stereotypy allowing individual recognition among rivals and mate choice for females. Recognition capabilities appear to depend on their breeding strategies, with males in territorial species that vocally discriminate between neighbors and strangers, whereas mate-guarding males seem to use phenotype-related acoustic cues to assess their rivals.