Patterns of Hibernation of Captive Citellus Lateralis and Eutamias Speciosus

Abstract

Observations of 20 mantled squirrels (Citellus lateralis) and 15 chipmunks (Eutamias speciosus) in captivity, in a cold room in temperatures of 4 to 6°C, revealed general patterns of hibernation. Captive C. lateralis, placed in the cold room in early September, began hibernation in early October, and E. speciosus followed in late October. C. lateralis aroused every 5 or 6 days near the beginning and end of hibernation, but individual periods of dormancy lasted about 14 days in midwinter. E. speciosus aroused every 1 or 2 days near the beginning and end of hibernation, and in midwinter was dormant for periods averaging 5 or 6 days. Likewise, at the beginning of hibernation, both species remained active for from 1 to several days during periodic arousals, but in midwinter they were active for only 1 or several hours between periods of dormancy. In an ambient temperature of 4°C, both species had rectal temperatures between 4.8 and 5.2°C when torpid. Breathing was slow for each species: 1 C. lateralis in an ambient temperature of 4.0°C with a rectal temperature of 5.2°C took 83 distinct breaths in 1 hour in an irregular pattern; and 1 E. speciosus in an ambient temperature of 4.0°C had a rectal temperature of 4.8°C and took 138 in 1 hour, in a more or less regular manner. Less extensive observations on 4 Eutamias quadrimaculatus and 10 E. townsendi showed that they are bona fide hibernators.