Публикации

22^ая международная конференция
Европейского Китологического Общества

22^th annual conference of European Cetacean Society

О конференции

• ABNORMAL MATING BEHAVIOR OF STELLER SEA LION BULLS

  Alexey V. Altukhov (1), Vladimir N. Burkanov (2,3)

  (1) Lomonosov's Moscow State University, Leninskie Gory 1/12, Moscow, 119234, Russia; (2)National Marine Mammal Laboratory, Seattle, Washington, USA; (3) Kamchatka Branch of the Pacific Institute of Geography, RAS, Petropavlovsk-Kamchatsky, Russia

  Steller sea lions display high dimorphism between sexes, as do all otariids. Steller sea lion males range from 300 to 350 cm in length, and 500 to 1000 kg in mass. Females are much smaller – maximum body length is 260 cm and the average weight is 350 kg. This difference in body size is closely related to social structure and life strategy, but it also has potential negative side effects. It is regularly observed that males kill females during mating, crushing them under their own weight. We observed 20 cases of death resulting abnormal copulation on Dolgaya Rock (Kuril Islands, Russia) during five breeding seasons (2003-2007). These events usually recur with the same bulls. The average male-killer causing death of 3 females during its stay on the rookery (min=1, max=5). Successful mating is also recorded for these males, but proportion of fatal copulations was about 29%. Copulation duration leading to death is longer (29.5 min), compare with duration of successful copulation which is similar to norm (20.8 min). Fatal copulations may be due to a combination of the greater body size of the bulls and the complicated topography of the rookery which reduces the mobility of females. All bulls-killers resided territories in difficult terrain surrounded by large boulders or lava flows and most of the dead females were trapped between the boulders during copulation. Furthermore, we observe one case when fatal copulation occurred in the same section of the rookery when a new male replaced the original male-killer. Apparently, number of fatal copulations decreases with experience of male, as the number of kills drops for a given male from year to year.
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