Mechanisms and impacts of migration by moose: The role of wildfire.

Anthropogenic disturbances and environmental change have resulted in the loss of migratory behaviors, an important life history strategy of many species. Identifying the mechanisms and ecological benefits of migratory behavior is important for conservation and management decision-making. We evaluated the putative mechanisms influencing partial migration in moose (Alces americanus) populations occupying landscapes characterized by anthropogenic and natural disturbances. We quantified differences in the ecology of moose that migrated or stayed resident on their winter range. Also, we assessed three possible effects of the choice to migrate: occurrence of parturition, adult survival, and cause of adult death. Wildfire disturbance in the winter range had the strongest influence on whether an individual migrated and most migratory moose experienced less wildfire disturbance in their summer range than their winter range. However, not all migrants were successful at reducing the amount of wildfire disturbance they experienced in their summer range. Moose were more likely to give birth if they migrated a relatively long distance in the spring of the previous year. Movement strategies did not affect the probability of adult survival, but they were associated with the causes of adult mortality. Residents were more likely to die of health-related causes while migrants were more likely to die from predation. Increased wildfire severity in the summer range, associated with warmer and drier climates, could alter migratory behaviors and the benefits of migration for moose.