Aggressive behavior between humpback whales (Megaptera novaeangliae) wintering in Hawaiian waters.
- C. Scott Baker and Louis M. Herman
Humpback whales (Megaptera novaengliae) wintering in Hawaiian
waters engage in strenuous aggression toward conspecifics. The social
context and sex of individuals involved suggest that aggression
is the result of male-male competition for sexually mature females,
including cows with newborn calves. Characteristic behaviors associated
with aggression occur in a roughly hierarchial scaling of intensity
and include broadside displays, underwater exhalations, head lunges
(in which the throat is inflated and enlarged), physical displacement,
and charge-strikes. Humpback whales do not form stable pair bonds
during the winter breeding season: females are seen serially and
simultaneously with multiple males and males are seen serially with
multiple females. Repeated observations of individually identified
whales indicate that escorting and singing are interchangeable reproductive
roles of mature males. Incidents of aggression show a seasonal increase
and decrease that parallel changes in abundance and average pod
size. A seasonal peak in the frequency of aggression probably related
to an increase in population density and to changes in the reproductive
physiology of mature males and females. It is suggested that singing
may function, in part, to synchronize ovulation in females with
the peak abundance of mature males on the wintering grounds.
Baker, C. S. and Herman, L. M. (1984). Aggressive behavior between
humpback whales (Megaptera novaeangliae) wintering in Hawaiian
waters. Canadian Journal of Zoology, 62, 1922-1937.
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