Behavioral responses of lynx to declining snowshoe hare abundance

Abstract

The behavioral responses of lynx (Lynx canadensis) to declines in snowshoe hare (Lepus americanus) abundance were examined in the southwestern Yukon. Between April 1982 and June 1984 11 lynx were radio-tagged and monitored within and near the Kluane Game Sanctuary. Lynx mean home range size increased from 13.2 to 39.2 km² concurrent with a decline in snowshoe hare abundance from 14.7 to 0.2 hares/ha. Below about 0.5 hares/ha several lynx abandoned their home ranges and became nomadic, although they remained within the general study area. Track transects through areas known to have different snowshoe hare densities indicated that, lynx concentrated their foraging efforts in areas of relatively high snowshoe hare abundance. Lynx abandoned these areas after hare abundance declined. Lynx foraging effort in terms of distance travelled per day showed a curvilinear relationship to snowshoe hare abundance. Straight-line daily travel distance remained constant at 2.2 to 2.7 km/day above 1.0 hare/ha. Below 1.0 hares/ha, straight-line daily travel distances increased rapidly, reaching 5.5 km/day at 0.2 hares/ha. Three of 7 radio-tagged lynx dispersed 250 km or more from the study area during the period of rapid decline in hare abundance in 1982. No similar long distance dispersal was recorded after hare densities stabilized at less than 1.0 hares/ha. Trapping mortality was responsible for the loss of 7 of 9 radio-tagged lynx that travelled outside the game sanctuary. One lynx died, and is believed to have starved, during the winter or spring of 1984. The high rate of trapping mortality outside the game sanctuary suggests that refugia in wilderness areas are important in maintaining lynx populations during periods of low recruitment.