NEAFWA 2018

AUTHORS: Daniel Ellingwood; Peter Pekins - Department of Natural Resources and the Environment: Wildlife Program, University of New Hampshire

ABSTRACT. In 2014-2017 we monitored 188 radio-marked adult cow and calf moose (Alces alces) to measure survival, and rate and cause of mortality in response to a declining population. Snow urine samples were used to measure urea nitrogen (UN) and creatinine (C) content to develop ratios that track the nutritional restriction of individual animals through winter, inclusive of the adult winter tick (Dermacentor albipictus) engorgement period. Samples (n = 173) were collected from 62 moose (45 calves, 17 cows) on a twice-monthly schedule from late January through snowmelt or calf mortality (March – early April). Low UN:C ratios ( 3.5) in late March, indicating rapid catabolism of muscle mass in response to heightened protein and energetic requirements. The majority of surviving calves (74%) and adult cows (100%) did not experience a spike in the UN:C ratio, indicating indirectly that habitat quality is probably not implicated in calf mortality. Further, the timing of the spike aligns with the peak feeding period of adult winter ticks. The primary cause of calf mortality in all years was associated with the heavy infestation of winter ticks that resulted in severe weight loss and signs of acute anemia consistent with massive blood loss. Additionally, the tick load in January (at capture) was the best predictor of calf survival, with body weight providing a counterbalancing effect for the heaviest calves.