Abstract
We evaluated the hypothesis that social play behavior influences the development of temperament in young animals, using docility as a measure of temperament. We observed the play behavior of juvenile Belding’s ground squirrels ( Urocitellus beldingi ) during the developmental period in which play primarily occurs and conducted behavioral tests measuring docility at the beginning and toward the end of the play interval. Tests involved handling squirrels and recording their responses. We observed a significant but weak association between body mass and docility at the beginning of the play period, suggesting that docility may vary with size or energetic variables. Docility decreased significantly among juveniles over the play interval, and rates of social play were reliable predictors of change in docility. Juveniles who played at higher rates tended to have greater decreases in docility over the play interval, suggesting that social play might refine temperament toward more active responses in U. beldingi . Rates of social play among juveniles were reliable predictors of their scores on docility tests as yearlings, suggesting that possible effects of juvenile play on docility may extend beyond the juvenile period. Among mothers of juveniles in the study, docility during gestation and lactation were reliable predictors of docility after emergence of young from the natal burrow. However, docility of mothers decreased significantly between gestation and emergence of young, suggesting that although squirrels have individual tendencies toward docility, the expression of these tendencies may be influenced by behavioral context. Significance statement This study helps to elucidate ways in which juvenile social play influences the development of young animals. Various studies have suggested that juvenile play influences motor, social, and cognitive development. Here, we show an association between juvenile social play and development of temperament in Belding’s ground squirrels ( Urocitellus beldingi ). Juveniles who engaged in play at higher rates across the play interval had greater behavioral shifts from passive toward active responses. Refinements in temperament toward more proactive behavior might have benefits for young animals such as better preparing them to explore, investigate, and gather information about their social and physical environments as they venture away from their natal areas.