Activity and use of active gravel pads and tundra by Caribou, Rangifer tarandus granti, within the Prudhoe Bay oil field, Alaska

We used ground observations and time-lapse videography to determine timing, activity, duration of use, and response to disturbance of Caribou (Rangife r tarandus granti) in relation to parasitic insect activity on 18 gravel pa ds and tundra within 1000 m of roads and pads in the Prudhoe Bay oil field, Alaska between 27 June and 31 July 1993. We found no differences in distri bution of bull dominated, cow/calf dominated, or mixed sex Caribou groups o n gravel pads or tundra; but there were differences in Caribou group activi ties on gravel pads and tundra. Caribou groups ran more often on tundra tha n on gravel pads. Caribou ran less often when mosquito (Aedes spp.) levels were low and more often when mosquito levels were moderate to high. Average group sizes were larger at high mosquito levels. Caribou were recorded on nine active gravel pads 2534 (42.9%) of 5906 hours that activity was monito red with time-lapse videography. Walking was the predominant activity while on gravel pads followed by standing and running. Caribou were observed sta nding under elevated production facilities and pipelines, and in shade next to buildings enclosing well heads, presumably to avoid harassment by paras itic insects. Caribou were recorded on gravel pads between 1300 and 2000 ho urs (ADST) with peak numbers occurring between 1300 to 1400 and 1800 to 190 0 hours (ADST). For most vehicle and human disturbances, Caribou on gravel pads responded by changing location on the pad.