, Volume 39, Issue 9, pp 768-778
Date: 04 Dec 2012

Killer whales (Orcinus orca) hunting for walruses (Odobenus rosmarus divergens) near Retkyn Spit, Chukotka

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Abstract

Group hunting by killer whales for walruses was observed in August 18, 2008, in the littoral area (3 km from the haulout of walruses, Retkyn Spit, Chukotka). The group of killer whales consisted of seven adults (one adult male did not participate in attacks) and two calves. Based on prey type, these killer whales were mammal-eating. The total duration of their hunt activity was not less than 95 min. The hunt consisted of three phases. The first phase was an attack on the group of walruses and choice of individual prey; the second phase was attacks on the chosen walrus; and the third (final) phase was a decrease in activity of killer whales and leaving group with walrus from sea shore. The main behavioral patterns of killer whales during the hunt were discerned. Two killer whales tried to kill walruses by chasing them and jumping out of the water on the shore. The video analysis of the “attack phase” showed that killer whales made 55 attacks on the walrus during 17.3 min. On average, each killer whale attacked the walrus seven times. The attack tactics of killer whales, the number of movements, and the location of killer whales (adults and calves) relative to each other and to the walrus were described. Well coordination of their movements and group actions was observed.

Original Russian Text © N.V. Kryukova, E.P. Kruchenkova, D.I. Ivanov, 2012, published in Zoologicheskii Zhurnal, 2012, Vol. 91, No. 6, pp. 734–745.