Reproductive Pauses by Female Caribou

Parturition status of 53 radiocollared, female caribou (Rangifer tarandus granti) of the central Arctic herd was determined through repeated observations by fixed-wing aircraft during 2–5 periods of parturition. The overall frequency of reproductive pauses for females that were initially parturient, or previously confirmed to be parturient, was 24% (ca. once every 4 years). Most pauses preceded (78%) and followed (87%) parturition events. Periodic infertility, as a response to nutritional stress, may enhance long-term reproductive performance in caribou and other ungulates.