Distribution and behavior of barren-ground caribou in relation to weather and parasitic insects

Abstract

Relationships between weather and the activity of mosquitoes (Culicidae) and oestrid flies (Oestridae), and responses by caribou (Rangifer tarandus) to insect harassment, were examined near Milne Point, Alaska. Weather conditions were usually unfavorable for insects within 20 km of the Beaufort Sea, and were least favorable within 1-3 km of the eoast. Weather affected the occurrence more than the level of insect activity. Mosquitoes were rarely active within 1 km of the coast; maritime weather conditions had little effect on oestrids. Weather conditions and insect activity were more variable through time than through space： this necessitated models predicting: (1) the presence of insects, and (2) levels of insect activity when insects were present. Insect harassment caused caribou to travel rapidly to coastal areas at the expense of feeding and lying, and form large, mixed groups. Insect activity was most highly correlated with caribou rate of travel and behavior.