REPRODUCTIVE STRATEGIES AND THE INFLUENCE OF DATE OF BIRTH ON GROWTH AND SEXUAL DEVELOPMENT OF AN ASEASONALLY-BREEDING UNGULATE - REEVES MUNTJAC (MUNTIACUS-REEVESI)

Unlike most species of deer, Reeves' muntjac does not have a seasonal reproductive cycle. Births are equally distributed throughout the year and, irrespective of season of birth, females start breeding when the y have reached a minimum body weight of about 10 kg. A significantly s maller proportion of females is born in the autumn/winter than the spr ing/summer, but there is no effect of maternal age or condition on foe tal sex ratios for first or subsequent pregnancies. Whilst aseasonal b reeding increases female productivity, males are only able to hold ter ritories encompassing the ranges of a number of does for a relatively short period of time. It is argued that for muntjac theres much less i nter-sexual variation in lifetime reproductive success than for season ally-breeding polygynous cervids. Hence, although muntjac are sexually dimorphic and polygynous, females do not invest preferentially in mal e off spring. Young males can be fertile from 36 weeks of age,when the ir first antlers are still in velvet. Whilst season of birth has no ef fect on the rate of sexual development in females, it does for males, with autumn-born male fawns attaining sexual maturity earliest. This a ccelerated development occurs in the period following independence fro m the mother, and there is no evidence of a maternal cost in producing male fawns. Since the canine tusks are the main weapons for intra-sex ual conflict, there could be clear gains in terms of reproductive succ ess for males that attain sexual maturity, adult weight and adult tusk size quickly, even though their first antlers are much smaller than t hose of older bucks. The hypothesis is presented that, for muntjac, th e majority of a male's lifetime reproductive success is achieved relat ively early in life when the canine tusks are in pristine condition, a nd that bucks lose their territories, and associated access to oestrou s does, once the canines are broken.