Patterns of spring emergence of the red-sided garter snake (Thamnophis sirtalis parietalis) in the Interlake region of Manitoba

Abstract

The period of spring activity of Thamnophis sirtalis parietalis at hibernaculum sites in the Interlake region of Manitoba lasts about [Formula: see text] months. This period is characterized by intense mating activity and a marked excess of males over females. Investigations begun in the spring of 1970 suggest that these two features are closely linked. Males begin emerging in large numbers at the end of April and reach a peak population size by mid-May. Females emerge in smaller numbers throughout the entire spring period and are immediately approached and mated by the males. After mating, the females disperse to the summer habitat. Males remain in the vicinity of the hibernaculum for a longer period, possibly mating several times, and begin to disperse in large numbers in the second half of May, It is suggested that communal denning and differential spring emergence are important aspects of the life-history strategy of these populations.