Influence of maternal characteristics and environmental variation on reproduction in Antarctic fur seals

Abstract

Abstract Antarctic fur seals breed synchronously in a highly seasonal environment. There is considerable inter-annual variation in food supply, which affects breeding performance. However, food supply may also influence future performance through effects on female ovulation, implantation and/or pregnancy. We used foraging trip duration, pup growth rate and weaning mass as indicators of the food available to females during the pup-rearing period (December-April) and examined relationships between these and pup production and timing of breeding in the following year. Productivity (pup production) was positively correlated with growth rate and weaning mass of both male and female pups in the previous season (P < 0.05) and negatively correlated with the variation around the mean birth mass of males (P < 0.05), suggesting that poor feeding conditions one season led to lower production the next. The timing of birth was positively correlated with foraging trip duration (P < 0.05) and negatively correlated with the birth and weaning masses of male and female pups, the duration of the perinatal period, growth of male pups, and the variation in the late-season growth (last two months) of male and female pups (P < 0.05 in all cases). This indicates that females give birth later in the season following a year when food resources were scarce.