Date of Graduation

Spring 5-18-2019

Document Type


Degree Name

Master of Science in Biology


College of Arts and Sciences



First Advisor

Scott Nunes

Second Advisor

Jennifer Dever

Third Advisor

Nicole Thometz


The ubiquity of play among juvenile mammals suggests it provides adaptive benefits, potentially through influences on the development of temperament in young animals. Juvenile Belding’s ground squirrels (Urocitellus beldingi) must balance competing demands for boldness and caution imposed by the fundamental trade-off between their short active season and their vulnerability to predation. In this study, I evaluated whether play helps to facilitate the development of an appropriate balance between boldness and caution in juvenile U. beldingi.I observed the play behavior of juvenile U. beldingiand conducted flight-initiation distance tests to measure boldness-caution at the beginning and toward the end of the developmental period during which play primarily occurs. I recorded the distances at which juveniles responded to intruders and the vigilance displayed by juveniles during tests as measurements of boldness-caution. The age of mothers was a significant predictor of the outcome of initial tests. Juveniles with yearling mothers responded to intruders at greater distances than did juveniles with older mothers. Juveniles exhibited increased caution in response to intruders over the play period. Age of mothers was a significant predictor of increases in vigilance displayed by juveniles over the play period, with juveniles with younger mothers having the largest increases. These results suggest maternal influences on the development of boldness-caution, with young of less experienced mothers developing greater caution. Rates of social play were significant predictors of increases in distances to notice and flee from an intruder over the play period, with juveniles who engaged in social play at the highest rates having the greatest increases. Other studies have indicated an association in some situations between social play and increased boldness rather than greater caution. Together with these studies, my results suggest that possible influences of play behavior on boldness-caution may vary with the context in which an animal finds itself.