Effects of summer Foraging Strategy on Reproduction and Survival of Moose in Northeast Washington

PhD Dissertation, James Goerz

In North America, moose (Alces alces) populations are experiencing widespread declines due in large part to the cascading effects of warming climate. These large, cold-weather adapted herbivores may have difficulty meeting the energetic demands of survival and reproduction amidst increasingly high seasonal temperatures. Late spring through early fall is a critical energy acquisition period for adult female moose when they must give birth, lactate, protect offspring, restore fat reserves, and breed again before the approaching winter. This physiological stress is compounded by the expanding presence of large carnivores across much of the Northwestern U.S. Paradoxically, moose in Northeast Washington are reportedly stable to increasing, raising interest in the possible behavioral mechanism responsible for their success.

We are currently monitoring 46 GPS/VHF radio-collared adult female moose within two study areas of Northeast Washington to estimate pregnancy, calf production, and adult/calf survival. To explain variation in these vital rates, we are studying the spatial and temporal foraging patterns employed by moose to meet the competing needs of energy acquisition and predator avoidance during critical but thermally-stressful summer months. Data obtained over the next three years may reveal behavioral plasticity in moose that increases their probability of persistence despite rapidly increasing temperatures and expanding large carnivore populations.