Predicting feeding site selection of mule deer on foothill and mountain rangelands

Abstract

Determining areas on the landscape selected by mule deer (Odocoileus hemionus) for foraging and the characteristics of selected feeding sites is a crucial step in managing mule deer and its habitat. Mule deer populations in much of western North America have been declining since the early 1990's, making management of mule deer increasingly difficult. Limited research has examined the characteristics of mule deer habitat that influence feeding site selection in foothill and mountain rangeland habitats during the winter and spring. The purpose of the study was to develop and validate models that incorporate the effects of important habitat variables that influence feeding sites chosen by mule deer in the winter and spring, including aspect, distance to forested cover, distance to hiding cover, distance to agricultural fields, distance to improved roads, distance to ranch roads, elevation, previous cattle grazing, and slope. Data collected in northwestern Wyoming between the summer of 1999 and spring of 2001 were used for model development, and data collected between summer 2001 and spring 2003 were used for temporal validation. Additionally, data collected in west-central Montana between summer 2001 and spring 2003 were used for temporospatial validation. Logistic regression was used to develop models for the winter, spring, and winter-spring seasons. Akaike's Information Criterion was used to determine the best models for each season. Models were validated on both a temporal and temporospatial scale. Six habitat variables (distance to improved roads, distance to ranch roads, distance to security cover, aspect, slope, and previous summer's cattle grazing) were included in model development after collinearity tests. Four models had a model sensitivity > or equal to 75% in both temporal and temporospatial validation. These models can be used to identify preferred mule deer feeding sites and assess potential impacts of land management practices on mule deer foraging habitat.