Summer elk habitat selection in southwest Montana

Data used in Ranglack et al. (in review), Modeling broad-scale patterns of
elk summer resource selection in Montana using regional and
population-specific models. Understanding animal distribution is important
for the management of populations and their habitats. Across the western
United States, elk (Cervus canadensis) provide important ecological,
cultural, and economic benefits and the sound management of their habitats
is of vital importance. In western Montana, National Forest lands are
managed in part to provide and protect elk habitat needs, and summer elk
habitat is managed with consideration to motorized routes. We evaluated
the relative importance of nutritional resources, access routes, and other
landscape attributes on elk summer resource selection at multiple spatial
scales, and compared resource selection among 9 different southwestern
Montana elk populations to determine the applicability of generalized
regional models for informing habitat management recommendations. First,
we developed 9 population-specific and 2 regional summer resource
selection models. Second, we evaluated the performance of each model
within and among elk populations using cross-validation scores to identify
the best model. We found that in all populations nutritional resources,
best represented using NDVI metrics, were the most important factors
associated with elk summer resource selection. Access routes affected
resource selection in all populations, however, the influence of access
routes was relatively modest as compared to nutritional resources. Of the
access route covariates we considered, the density of all routes (i.e.,
routes open and closed to motorized use) explained the most variation in
summer elk resource selection. Validation of population-specific resource
selection models among populations revealed that in many cases model
predictions extrapolated to areas outside of the development area had
modest to poor predictive performance, especially as the distance from the
modeled population increased. Thus, caution should be used when
extrapolating resource selection models based on a single study population
to other populations. Regional models of resource selection predicted
resource selection across populations better than population-specific
models, particularly when constructed by pooling data from multiple
populations, and we recommend these types of models be used to inform
regional habitat management policies. Our results suggest that managers
should expand the current management paradigm for elk summer habitat that
is focused on limiting access route density to also consider nutritional
resources as an important component of elk summer habitat.