Date of Graduation


Document Type


Degree Name

Master of Science in Biology


College of Arts and Sciences



First Advisor

Scott Nunes

Second Advisor

Naupaka Zimmerman

Third Advisor

Tracy Benning


Play behavior is ubiquitous among young mammals and has a variety of important influences on early development. I evaluated possible influences of social play behavior on the development of temperament in juvenile Belding’s ground squirrels (Urocitellus beldingi), using the caution/boldness spectrum as a measure of temperament. I disrupted the play behavior of juvenile U. beldingi by walking toward juveniles at play until the play interactions stopped. I used undisrupted juveniles and juveniles whose non-play behavior was disrupted at regular intervals as controls. Caution was measured with behavioral tests during which a human intruder walked toward a squirrel and recorded the distances at which the squirrel first noticed and then fled from the intruder. Rates of social play were lower and play bouts were shorter in playdisrupted juveniles than in undisrupted and non-play disrupted juveniles. The distances at which juveniles noticed and fled from an intruder increased across the developmental period in which play primarily occurs, suggesting increases in caution across this interval. Increases in the distances to notice and flee from an intruder did not differ between undisrupted and non-play disrupted juveniles, but were greater in these groups than in play-disrupted juveniles. These results are consistent with social play behavior promoting the development of cautious responses in juvenile U. beldingi.

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