THERMOREGULATION BY MULE DEER (ODOCOILEUS-HEMIONUS) IN ARID RANGELANDS OF SOUTH-CENTRAL WASHINGTON

Temperature-sensitive, radiotelemetry transmitters were used to measur e body temperatures of six free-ranging, adult, female mule deer (Odoc oileus hemionus) in the semi-arid shrub-steppe of southcentral Washing ton from 1988 to 1990. Body temperatures ranged from 37.5 to 39.7-degr ees-C and were similar to rectal temperatures reported for Odocoileus. Temperatures followed distinct circannual and circadian patterns unre lated to changes in air temperature or solar radiation. Behavioral the rmoregulation may have been important in helping deer avoid thermal st ress at environmental temperatures that often exceeded 25-degrees-C. O n hot, clear days, deer sought beds that provided refuge from solar ra diation yet permitted radiative heat loss.