The function of male aggressive displays towards females in mountain gorillas |
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Authors: | Pascale Sicotte |
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Institution: | (1) Department of Anthropology, University of Calgary, 2500, University Dr., N.W., T2N 1N4 Calgary AB, Canada |
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Abstract: | In groups ofGorilla g. beringei, male aggression towards females regularly takes the form of male display. This paper examines male display towards females
in two Karisoke study groups (Group 5 and Group BM) in 1989, a period when none of the females were new immigrants. Results
are based on 259 hr of focal observations and 121 hr ofad libitum observations on male behaviors towards females. The goal is to see if the data are compatible with four non-mutually exclusive
hypotheses to explain male displays towards females: (1) demonstration of male fighting abilities to influence female long
term residence decision; (2) decrease potential competitive inequities between females; (3) provision to females of an occasion
to confirm their subordinance to a male; and (4) short term influence on mating. First, male-female proximity was tested against
proportion of male displays, to rule out the possibility that males display towards females simply because they happen to
be close by. There was no association between proximity and male display. Dominant males were responsible for a higher proportion
of displays than subordinate males. This is consistent with the idea that males display to demonstrate their fighting abilities,
or their qualities as protector, since dominant males are the ones offering long term protection against infanticide and predators.
Females that were in a position to transfer did not receive a higher proportion of male display, however. Long term resident
dominant females received a higher proportion of displays from the dominant males, which is consistent with the idea that
males attempt to decrease potential competitive inequities between females. There was an association between female appeasement
reactions and male displays, which suggests that males display to create occasions for the females to confirm their subordinance
to them. Estrous females did not receive a higher proportion of male displays, and there was no association between male display
and copulation, suggesting that male displays are not a form of courtship aggression aimed at influencing mating in the short
term. |
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Keywords: | Gorilla g beringei Male display Male-female relationships |
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