MULE DEER AND PRONGHORN USE OF WASTE-WATER PONDS IN A COLD DESERT

Pronghorn (Antilocapra americana) and mule deer (Odocoileus hemionus) were counted at wastewater ponds at the Idaho National Engineering and Environmental Laboratory (INEEL) in southeastern Idaho 4 to 8 times p er month from August 1989 through July 1991. Mule deer used wastewater ponds (n = 15) from June through December and were most commonly obse rved August through November Pronghorn frequented wastewater ponds fro m May through November and were most common from July through Septembe r, the driest and warmest months; ponds were also used heavily in Nove mber 1990. Diel activity was studied from July through October. Mule d eer use of ponds varied in relation to 8 diel time periods in August ( P = 0.02) and September (P = 0.01) while pronghorn use varied by time period (P < 0.01) in all 4 months. Mule deer were more active at ponds during nocturnal than diurnal counts from July through September (P < 0.01). Pronghorn diurnal activity exceeded nocturnal activity (P < 0. 01) August through October. Mule deer and pronghorn use of ponds was n ot related to distance from site facilities (groups of buildings used for research and other purposes). Pronghorn made greater use of indivi dual ponds lacking additional nearby watering sites, and both pronghor n and mule deer were attracted to ponds with grass/forb and shrub cove r around the upland periphery.