Modeling winter severity and harvest of moose: impacts of nutrition and predation

Abstract

Climate change is expected to have both positive and negative impacts on northern ungulate populations. Moose (Alces alces) will likely benefit from an increase in the growing season length and frequency of wildfire. However, increases in extreme weather events may result in moose population declines, particularly for nutritionally stressed moose populations. Management strategies to reduce the nutritional stress of populations may become increasingly important. We used stage-structured population models to examine the impact of deep-snow events on moose population trajectories and evaluated female harvest strategies designed to mitigate nutritional stress by decreasing intraspecific competition. Population trajectories were primarily influenced by young adult and prime adult survival. Populations held at low density by predation are likely buffered against the effects of severe weather events, whereas nutritionally stressed populations are vulnerable to population declines from the same environmental conditions. Harvest of cow-calf pairs may be an effective way to maximize harvestable yield and maintain population resilience when nutritional condition is poor. Moose population abundance over the long-term may become more variable due to the effects of climate change. Future modeling needs to incorporate alternative harvest and climate scenarios to help us better understand how we can promote moose population resilience.