The San Joaquin antelope squirrel (Ammospermophilus nelsoni, "SJAS") is a burrowing rodent endemic to the San Joaquin desert, listed as threatened under the California Endangered Species Act. Antelope squirrels are known to retreat to their burrows during the hottest parts of the day in summer as a thermoregulatory mechanism, but little is known regarding the specifics of this approach in this species. From July to September, 2021, we conducted a pilot project using thermally sensitive VHF radio collars to answer three questions: (1) What causes SJAS to emerge in the morning (temperature, sunlight, or both); (2) how much total time do SJAS spend above ground daily, and is this time related to temperature; and (3) what temperatures cause SJAS to descend back into their burrows during the day? We developed a novel approach to classify squirrels as above- or below-ground based on collar temperature and used this classification to answer this question for two squirrels. For the time period of the study (i.e., mid- to late-summer), antelope squirrels emerged from their burrows on average within 15 minutes of sunrise, regardless of temperature. We found that for every 1 F increase in maximum daily temperature, squirrels spent approximately 8-10 fewer minutes aboveground. Finally, squirrels retreated to their burrows when daily temperatures reached approximately 89-91F. Our results were consistent with previous qualitative observations of antelope squirrel behavior, as well as with a previous estimate of their critical upper maximum temperature. Future studies would benefit from light loggers rather than temperature sensitive collars to better time emergence and retreat, as well as a larger number of squirrels across a broader time period.