AGE AT FIRST REPRODUCTION IN MALE FALLOW DEER - AGE-SPECIFIC VERSUS DOMINANCE-SPECIFIC BEHAVIORS

The argument that an optimal age at first reproduction evolves where t he benefits of reproduction outweigh the costs implies that where cond itions change, age at first reproduction should also change. We studie d six captive populations of allow deer (Dama dama) that differed in t he age structure of males, male density, and sex ratio. We examined re sponses of males to changes in competition by simulating the presence of additional males by providing visual, olfactory, and auditory stimu li. Our results suggest that dominance rank was the most important fac tor in determining the level of reproductive behaviors exhibited. The participation in reproduction increased with dominance status, and thi s association held for males that are usually socially immature (3-5 y ears old). Hence, age apart from dominance was relatively unimportant in affecting the reproductive behavior. Male density was positively co rrelated with the time spent walking and standing. The female-to-male ratio was positively related to male-female interactions, but negative ly related to male-male interactions. In response to the simulations, males older than 3 years increased the rate of reproductive behaviors, but younger males did not change or decreased the rate. We conclude t hat only males up to 3 years of age refrained from reproduction under competition by mature males. However, past 3 years of age, investment in reproduction is a function of dominance rather than a function of a ge. This implies that 4- and 5-year-old males do not seem to defer rep roduction until socially mature but that their participation is a corr elate of the achievable dominance rank.