Growth of pika in laboratory confinement.

Captive-born pikas (Ochotoma princeps) from 13 litters were maintained for up to three months in a laboratory setting. Mean litter size was 2.69 +/- 0.75, with litters of three the most frequent, and representing 68% of all litters observed. Mean individual birthweight was 11.7 g with a range of 8.8 to 16.8 g. Weights were taken every other day from birth, which yielded a growth curve equation of y = 12.18 + 1.72x. There was a strong positive linear correlation between bodyweight and time (r = 0.98, P less than 0.001), and a significant difference was noted between sexes, with females the heaviest. Subjects reached adult weight within 3 months. These data represent the first reports of growth in this species, and indicate that pikas are among the fastest growing species within the order Lagomorpha.