The Reaction of Barren-Ground Caribou to Aircraft

The responses of barren-round caribou to fixed-wing aircraft and to helicopters were observed in the northern Yukon and Alaska. Effects of aircraft altitude, type of aircraft, season and terrain were determined together with the activity and size of group of the caribou. Panic reactions or strong escape reactions were observed in a high percentage of all groups when aircraft flew at altitudes of less than 60 metres. Flying at a minimum aircraft altitude of 150 metres during spring and fall migrations, and 300 metres at other periods, would prevent the caribou reacting in the ways most immediately injurious to them.