Laboratory observations of aggregative behavior of garter snakes, Thamnophis sirtalis

A laboratory model of garter snake aggregation behavior is described. Snakes tested in groups of eight established preferred shelter locations and reliably returned to these locations as a group or as individuals when the test aquaria were left undisturbed between trials. When the aquaria were cleaned and the contents were replaced on each trial, preferred shelter locations were not established over trials; however, the snakes were found under shelters in large aggregates more frequently than would be expected by chance. It appears that the snakes deposit cues in the apparatus that are subsequently used to return to preferred locations. Manipulations of various objects in the test arena strongly indicated that the relevant cues are deposited on the paper underlying the preferred shelter.