Premature loss of winter hair in free-ranging moose (Alces alces) infested with winter ticks (Dermacentor albipictus) is correlated with grooming rate

Abstract

Premature loss of winter hair coat can be a serious problem for moose (Alces alces), possibly leading to escalated heat loss and depleted reserves. Studies of captive moose have indicated that premature winter hair loss is associated with infestation by winter ticks (Dermacentor albipictus), and the extent of hair loss is associated with grooming efforts directed at removing the ticks. In this study we observed the grooming behaviour and hair-loss patterns of wild moose throughout the winter to test the prediction that the extent of hair loss would be positively correlated with the rate of grooming actions (oral grooming, scratching, and rubbing). Moose were observed throughout the winter of 1995-1996 at Elk Island National Park, Alberta. Both the proportion of hair loss and the rate of grooming increased from October through April, with hair-loss and grooming rates highest during the period of adult tick engorgement in March and April. Correlation analysis showed that moose which groomed more experienced greater hair loss. Increased grooming effort was negatively associated with feeding activity, possibly because moose sacrificed feeding time in order to remove engorging ticks; however, metabolic or anorectic effects cannot be ruled out. Despite the potential cost of hair loss from increased grooming, total fitness costs may be greater for moose that fail to groom adequately and subsequently suffer blood loss from feeding nymphal and adult winter ticks.