ADAPTATIONS OF WINTER TICKS (DERMACENTOR ALBIPICTUS) TO INVADE MOOSE AND MOOSE TO EVADE TICKS

Abstract

Most North American moose (Alces alces) outside Newfoundland and south of 60° N latitude are infested annually with winter ticks, Dermacentor albipictus. Moose commonly are host to many thousand winter ticks, and tick-associated die-offs of moose are reported often. Larval winter ticks display such behavior as aggregating in clumps on the leeward side of vegetation at heights of preferred ungulate hosts, apparently aiding in their survival and in contacting vertebrate hosts. Moose, in turn, avoid or reduce infestation by ticks by evading tick larvae on vegetations, tolerating tick-foraging by magpies, and grooming to remove ticks. Recent evidence that grooming by African antelope and North American bison and wapiti is regulated by a centrally controlled mechanism that acts to evoke a preventative grooming before ticks can attach and feed, ahs not been supported for moose. This paper reviews host-finding adaptations of winter ticks, pathenogenic characteristics of winter ticks for moose, the relationship between magpies and moose, and the biological basis of grooming in moose.