Early auditory experience and the ontogeny of alarm-call discrimination in Belding's ground squirrels (Spermophilus beldingi).

Because young ground squirrels are vulnerable to predation, selection would favor the early ability to respond to alarm calls. This requires discrimination of classes of alarm calls from each other as well as from non-alarm calls. Pre-emergent auditory experience may influence the development of discrimination. As a means of determining when Belding's ground squirrels (Spermophilus beldingi) can discriminate among calls, cardiac responses to alarm calls and control stimuli were recorded from 2 rearing groups that differed in the frequency of alarm-call exposure. Results suggest that before natal emergence, young can discriminate between 2 classes of alarm calls but they may not discriminate these calls from control stimuli. No differences in responses were found between the rearing groups; thus experience with calls may not influence the onset of discrimination. Early discrimination may facilitate the rapid development of post-emergent behavioral alarm-call responses.