Abstract: social organization of mammal-eating killer whales (fwd)

From: pita admininstrator (pita@www1.wheelock.edu)
Date: Sun Nov 19 2000 - 18:33:26 EST

Subject: Abstract: social organization of mammal-eating killer whales

Baird, R.W., and H. Whitehead. 2000. Social organization of mammal-
eating killer whales: group stability and dispersal patterns. Can. J. Zool. 78:

Abstract: The social organization of mammal-eating "transient" killer whales
(Orcinus orca) was studied off southern Vancouver Island from 1985 through
1996. Strong and long-term associations exist between individual
transients, so sets of individuals with consistently high association levels,
termed pods, can be delineated. Pods consist of individuals of mixed ages
and sexes, and typically contain an adult female and one or two offspring
(averaging 2.4 individuals). The mother-offspring bond remains strong into
adulthood for some male (and less often for female) offspring. Other males
disperse from their maternal pod and appear to become "roving" males,
spending some of their time alone, and occasionally associating with
groups that contain potentially reproductive females. These males appear to
have no strong or long-term relationships with any individuals, and adult
male - adult male associations occur significantly less often than expected
by chance. Females that disperse from their natal pod appear to be
gregarious (having high average association rates) but socially mobile
(having low maximum association rates). Differences in social organization
from the sympatric fish-eating "resident" killer whales (where no dispersal of
either sex occurs) likely relate to differences in foraging ecology. Transient
killer whales maximize per capita energy intake by foraging in groups of
three individuals, whereas no such relationship has been documented for
resident killer whales.

Robin W. Baird, Ph.D.
Post-doctoral Fellow, Dalhousie University, Canada
E-mail: rwbaird@is.dal.ca

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