EARLY MATERNAL INVESTMENT AND GROWTH IN REINDEER

I studied whether females in a herd of semidomesticated reindeer (Rang ifer tarandus) in Finland invest more heavily in male than in female o ffspring and whether the mother's body size and condition have differe nt effects on growth rates of male and female offspring. The results d id not provide evidence of different preweaning investment in male and female offspring. Proportional mass loss of breeding females during c alving was greater when the calf was male than when it was female, but change in mass between consecutive autumns did not depend on the sex of the calf. In general, the growth of male and female calves depended in approximately similar fashion on maternal characteristics, but amo ngst the male calves only, the growth rate from birth until the follow ing November depended on the mother's change in mass the previous wint er. Mass loss of parturient females was inversely related to mass loss during pregnancy. Females that experienced heavy mass loss from Novem ber until postcalving gained the most mass before the following Novemb er. Winter food supplementation probably led to large body masses and a low mortality rate of calves and might have masked differences in re productive costs associated with producing male and female calves.