Lifetime patterns in adult female mass, reproduction, and offspring mass in semidomestic reindeer (<i>Rangifer tarandus tarandus</i>)

Abstract

The objective of our investigation was to examine relationships between lifetime patterns of female mass, calving incidence, and offspring mass in semidomestic reindeer (Rangifer tarandus tarandus). The analyses were made on data recorded from 1986 to 1997 on semidomestic reindeer in the herding district of Ruvhten Sijte in Sweden. A female rearing a calf was shown to weigh 3.1 ± 0.3 kg (mean ± SE) less in winter than a female not rearing a calf. The difference in calving incidence between females rearing a calf in the previous year and those not rearing a calf in the previous year was small, but there was a tendency for old females to have a decreased calving incidence if they had reared a calf in the previous year. The average calving percentage for adult females was 73%. Calf masses were affected by both the mother's mass and her age. The regression coefficient of calf autumn mass on female mass the previous winter was 0.26 ± 0.02. Mothers aged 2–4 years had calves that weighed less than calves of older mothers. The average difference in autumn mass between male and female calves was 2.9 ± 0.2 kg, but the difference was less for calves with mothers aged 2–4 years. We obtained lifetime patterns of female mass, calving incidence, and offspring mass. We also gave an organized structure of relationships between these traits.