Socio-ecological drivers of resource selection and habitat use by moose in Interior Alaska

Abstract

Sustainably managing wildlife with diverse utilization values is one of the greatest challenges facing contemporary wildlife management. These challenges can be amplified under changing environmental and socio-economic conditions. In Alaska, boreal forest systems are experiencing rapid change as a result of climate warming. Alaska’s boreal region has warmed twice as rapidly as the global average, affecting a host of processes including an increase in wildfire frequency, extent, and severity. Wildfire is the most common ecological disturbance in the Alaskan boreal forest and an important driver of landscape heterogeneity, burning on average 1 to 2 million acres per year. Fire severity is a particularly important factor dictating the regeneration of deciduous species, and one that can influence the overall quality of habitat for herbivores, such as moose (Alces alces). However, the relationships between the availability and duration of biomass production and moose habitat selection are largely unknown. Additionally, the effects of fire on wildlife resources in Alaska can have important consequences for boreal social-ecological systems as well. Fire-related changes to the community composition of forest stands would likely affect the densities of species that human communities rely on for hunting and trapping. In Interior Alaska, where natural wildfire is the primary means of increased browse production for moose, managers may want to consider incorporating burns into management plans while paying particular attention to hunter accessibility. However, an increase in hunter activity into moose habitat could result in changes to moose distribution and activity patterns near trails and roads. To examine these questions I utilized telemetry data from 26 moose along with methods in spatial ecology, plant-animal interactions, resource selection and human dimensions of wildlife research to predict the influence of an ecological disturbance (fire) and an anthropogenic disturbance (hunter activity) on moose habitat use. I used dynamic Brownian bridge movement models (dBBMM) in conjunction with browse assessment surveys to examine how fire severity, via its control over vegetation composition, forage production and nutritional quality, affect habitat use patterns of moose across their seasonal home ranges and core use areas. To assess the effects of hunter activity on moose habitat use, I created fine-scale stepselection models to test whether habitat selection and movement patterns were affected by spatio-temporal variation in risk from hunting activity. Additionally, from August-October, I used a camera trap array to collect field data on human activity (off-road vehicles, automobiles, 4x4 trucks, dirt bikes, and hunters afoot) together with the RandomForests algorithm to create high-resolution hunter distribution models. Finally, to integrate my research within a socialecological framework, I examined the interactions between wildfire, forage production and hunter access on management scenarios overtime. In winter, moose preferred low-severity sites more than high and moderate-severity sites, but in summer, moose selected for high-severity sites. Forage biomass production ranged from 62 to 243 kg/ha/yr across all sites during winter within the Hajdukovich Creek Burn, but production and availability varied depending on fire severity and browse species. These results indicate that differing distributions of wildfire severity across a landscape can create a dynamic, mosaic of habitat patches that may optimize and extend the value of burns over time for moose. I found that while moose selected habitat closer to trails and roads, they also avoided areas with more hunting activity. Finally, my management scenarios provide a framework for managers to adapt goals and actions to changing conditions that can affect moose-hunter systems. I recommend that wildlife conservation and management decisions consider these methods as we seek to sustainably manage wildlife for future generations during a time of rapid socio-ecological change in Alaska.