Resource selection is used here in reference to a suite of methods to determine resource or habitat use by an animal that can be measured in a heirarchical fashion (i.e., First order through Fourth Order; Johnson 1980). The appropriate method to use is determined by the data that was collected during the study that is often controlled by logistics, funding, and population size of the species studied. As methods to identify animal use of the landscape (i.e., GPS technology) and measures of resource or habitats (i.e., GIS layers) have improved, the methods to analyze data has evolved as well (Cooper and Millspaugh 2001, Manly et al. 2002). Several commonly used measures of habitat use or resource selection include:
- Compositional Analysis (Aebischer et al. 1993)
- Mahalanobis Distance (Clark et al. 1993)
- Selection Ratios (Manly et al. 2002)
- Resource Selection Functions (Cooper and Millspaugh 2001)
Before we begin with resource selection, we first need to prepare the data that we are interested in incorporating into our modeling efforts. Whether these are linear measures (e.g., distance to roads) or landscape/topographic characteristics (e.g., elevation, slope), summarizing variables as used or available can be completed all in R. Some of these methods were presented in Chapter 1 so we will build on that before estimating RSF/RSPF in later sections of this chapter.
