Abstract:
I studied sexual segregation in mule deer (Odocoileus
hemionus) and white-tailed deer (Q. virginianus) in
different environments and at different population
densities to test the hypothesis that sexual segregation
occurs in ungulates as the result of different
reproductive strategies; females select habitat and behave
in manners primarily designed to promote offspring
survival, while adult males act primarily to maximize
energy stores prior to the rut. Data collected for both
species were consistent with this hypothesis. Mule deer
segregated both socially and spatially. Compared to
males, female mule deer used areas that were closer to
water, supported superior browse species, and provided
greater security for offspring from coyotes. Locally
available resources enabled females to minimize movements,
the apparent consequence of which was the depletion of
forb biomass, the major diet class for both sexes. Males
ranged further than females, a strategy that provided a
diet high in forbs and high in quality. The occurrence of
mixed-sex groups in highly productive areas suggested that
males responded to forage availability and not females perse, and that the effects of localized grazing pressure by
females may competitively exclude males from areas.
Sexual segregation was not maintained by intersexual
aggression in either mule or white-tailed deer. White tailed deer segregated socially, but demonstrated broad
spatial overlap. During the peak of segregation
(June-October), male behaviors were consistent with a pre-rut
energy saving and forage seeking strategy; males used
larger areas and made longer short term movements than
females, but were less active overall and were relatively
more active at night. Females were less mobile and
foraged in smaller areas than males, particularly during
fawn rearing periods (June-October). I also tested the
hypothesis that male white-tailed deer segregate and range
widely to scout potential mates and rivals. Based upon
comparisons of areas used by radio-collared males and
females during the peak periods of segregation (June-September) with areas used during the rut, this hypothesis
was rejected.
