Pup abduction and infanticide in southern sea lions.

CAMPAGNA, C.; LE BOEUF, B. J.; CAPPOZZO, H.L

BEHAVIOUR

Brill Academic Publishers

Lugar: Leiden; Año: 1988 vol. 107 p. 44 - 60

0005-7959

Southern sea lions, Otaria byronia, seize suckling pups and take them away from the breeding animals. Females did not leave the central breeding area in pursuit of their pups. During four breeding seasons we recorded 285 pup seizures. A mean of 21% of 400 pups born each seasons were seized by subadult males. 57% of the pups seized were abducted and held captive. Subadult males treat pups in the same way that adult males treat adult females, sequestering them and preventing their escape. Males were possessive, held pups for up to two hours, and defend them from other males. Pups attempting to escape were bitten, shaken from side to side, and tossed into the air. In 9% of the abductions, males mounted pups, but intromission did not occur. Abducted pups were sometimes injured and killed. Some pups had bite wounds on the neck, back and flippers, and lacerations on the head and neck; 5.6% of the pups seized, and 1.3% of the pups born each season died to physical abuse. Dead pups had tooth punctured wounds and extensive haematomas. In addition, 19 pups abducted during four seasons were taken to sea; nine of them were not seen again and may have drowned. Since breeding is seasonal, females that lose a pup lose an entire breeding year. Males do not obtain immediate reproductive benefits from pup abductions. Pups may be used as female substitutes by males that are sexually but not physically competitive with adults for mature mates. Through practice with pups, ousted males may gain experience in controlling adult females. Infanticide appears to be a by-product of males treating pups as females. Pups are vulnerable because of the superior force and larger size of abductors.