Field observations on Galápagos fur seals and sea lions indicate mutual recognition between mother and pup. High calling activity and intensive interactions of mother and pup immediately after birth appear to establish recognition within the first few hours (mother) or days (pup) of birth. Females of both species nurse exclusively their own young and reject strange ones, sometimes very aggressively. The prompt reactions of pups to their mothers' Pup Attraction Calls (PACs) suggest that the mother too is individually recognized. The analysis of the PACs of mothers and the bleats of pups shows that interindividual variability of calls provides a sufficient basis for individual recognition in both species. Playback experiments with PACs of fur seals and sea lions show that pups (10 days to 2 years old) can discriminate between their mothers' and strange females' PACs. Mother recognition reduces the frequency of dangerous encounters of pups with strange females or allows pups to approach strangers especially careful, thus reducing the risk of injury. Only by means of individual recognition can females in crowded otariid rookeries limit maternal investment to their own offspring. The mechanism of individual recognition in dispersed, ice-breeding phocids and colonially breeding otarid seals may be different.
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