Growth and Development of the Round-tailed and Harris Antelope Ground Squirrels

Abstract

Captive round-tailed ground squirrel (Citellus tereticaudus negleetus) females gave birth to four litters (26 individuals), and Harris antelope squirrel C. harrisii harrisii) to two litters (13 individuals) on which growth and development data were obtained. The round-tailed ground squirrels are larger and have the faster rate of development during their early life, as demonstrated by the earlier appearance of hair on the head, eruption of lower and upper incisors, and opening of eyes. In weight and in linear measurements, the round-tailed ground squirrels have a faster growth rate than do the Harris antelope squirrels. Linear measurements do not show this difference as readily as do weights. Rapid growth and development is a characteristic of mammals that hibernate, thus the more rapid growth rate of the round-tailed ground squirrel was explained, at least in part, when it was found that it hibernated but the Harris antelope squirrel did not.