Aerial Winter Census of Caribou

Bergerud, Arthur

During 1957-61, 400 hours of flying time were spent in censusing caribou (Rangifer tarandus) in Newfoundland and Labrador. The standard strip census method was used with two rear-seat observers, each scanning a ¼-mile strip. In northern Labrador, the strip was increased to ½ mile. Caribou were reported by rear-seat observers through an intercommunication system to the front-seat navigator, who plotted the animals on large-scale maps or aerial photographs. An estimation was made of the caribou missed by the rear-seat observer by comparing the results of three observers scanning the same strip. Herd structure and distribution were affected by snow cover. Shallow snow depths resulted in low, uniform densities and large herd areas. Densities and heterogeneity were increased when soft snow levels were higher. One herd of 2,000 animals received 88 percent aerial coverage over a 2-day period. Statistics for caribou per square mile were determined at various sampling intensities, using three systematically spaced transect patterns and a random flight design, and compared with figures secured with 88 percent aerial coverage in the systematic design and 79 percent aerial coverage in the random design.

Aerial Winter Census of Caribou

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