UC Davis

This study of California ground squirrels (Otospermophilus beecheyi) investigated the long-term effects of isolation rearing on alarm-call recognition. Six wild-caught squirrels, trapped as yearlings, and six laboratory-reared squirrels were maintained in solitary cages for approximately 3 years prior to the study. Visual searching and olfactory searching were measured as squirrels emerged from their burrow-like nest box into a laboratory room after hearing repetitive playbacks of alarm calls or control sounds consisting of pulses of white-noise or ambient laboratory sounds. Before exiting completely after hearing alarm calls, both groups exhibited similar levels of visual searching that was reliably higher than after hearing the other sounds. After exiting completely, the laboratory-reared squirrels exhibited a reliably greater amount of olfactory investigation than the wild-caught squirrels. Five laboratory-reared squirrels turned around after exiting and inspected their dark nest-box opening, three of which tail flagged repeatedly and one threw substrate into the opening. Since pups recognize snakes and engage in this behavior, this latent expression of antisnake behavior illustrates its robust organizational properties in the appropriate burrow-like context irrespective of the presumed retardation of neural development known to occur in other species of rodent subjected to similar isolation rearing.