Antler Mass of Barren-Ground Caribou Relative to Body Condition and Pregnancy Rate

Abstract

Antlers of caribou (Rangifer tarandus) likely contribute to breeding success of males, defence of feeding sites by females, and recognition of the hierarchical status of conspecifics. However, few data are available on how antler mass is related to age, body mass, fat reserves, other physical indices, and reproduction. Mass of antlers was recorded for 958 caribou obtained in early and late winter, 1982 through 1987, from the Beverly herd of barren-ground caribou (R. t. groenlandicus) in north-central Canada. In females, antler mass increased with age to 14 years, whereas mean body mass was stable from 7 through 13 years. Female antler mass correlated with body mass, body size, fat indices, and pregnancy rate both among and within age classes. In males, antler mass correlated highly with lean body mass to age 4 years. Antler mass varied among years in concert with fatness in females and with changes in body mass in both sexes. We conclude that antler mass is an index of body mass, body size, condition, and pregnancy rate, but high variation makes it inferior to other indices.