. The Canadian field-naturalist. 1998 Noel, Pollard, Ballard, and Cronin:Use of Gravel Pads and Tundra by Caribou 403 Table 2. Chi-square test for heterogeneity of Caribou group types observed on tundra within 1000 m of roads and on gravel pads during road surveys in the Prudhoe Bay oil field, Alaska, summer 1993. Number of Groups and Type Case Bull Cow/calf Mixed Gravel Tundra Observed Expected Cell Chi-square Observed Expected Cell Chi-square "hi-square = 108 367 84 0 271 0 14 11 33 36 Overall ( P= recorder with a Panasonic™ WV-CL 32
. The Canadian field-naturalist. 1998 Noel, Pollard, Ballard, and Cronin:Use of Gravel Pads and Tundra by Caribou 403 Table 2. Chi-square test for heterogeneity of Caribou group types observed on tundra within 1000 m of roads and on gravel pads during road surveys in the Prudhoe Bay oil field, Alaska, summer 1993. Number of Groups and Type Case Bull Cow/calf Mixed Gravel Tundra Observed Expected Cell Chi-square Observed Expected Cell Chi-square "hi-square = 108 367 84 0 271 0 14 11 33 36 Overall ( P= recorder with a Panasonic™ WV-CL 322 color CCTV digital camera equipped with a Computar^"^ APC auto-iris mm semi-wide-angle lens (f ). Each video system was powered by four Powersonic™ 12-volt, 80-amp batteries connected in a parallel sequence. Batteries were charged by four Solarex™ SX-56 photovoltaic panels connect- ed in a parallel sequence. The solar panel array was oriented at a 15° angle from the gravel pad surface and faced due south. The recorder, camera, and bat- teries were contained in individual weatherproof aluminum housings, specially constructed and insu- lated to protect the equipment from extremes in environmental conditions (Figure 2). Video cameras had a 72° field of view, and Caribou could be distinguished to a distance of about 60 m. Each camera sampled Caribou abun- dance and activity within a 2268 m^ area. However, buildings, pipelines, and other structures reduced this visible area at some pads. The camera systems were in continual operation (24 h/day) from 3 July to 31 July and were pro- grammed to record images at 2-sec intervals. Memorex^'^ Pro Cam 120-min VHS tapes were ana- lyzed by replaying them on the GYYR™ time-lapse recorder connected to a 21-inch color television. The following data were recorded: date, time, dura- tion, group size, group type, and activity (walking, running, standing, resting, insect harassment, and disturbances). An observation began whe
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