Exploring Spatial Analysis Techniques for Quantifying Landscape Structure and Pygmy Rabbit Habitat Selection at Multiple Scales

Society for Range Management ConferenceSociety for Range Management Conference, Spokane, WA, 28 January to 03 February 2012

Virginia Harris

“High resolution remotely sensed images (~ 1 m pixels) are becoming increasingly accessible at little to no cost. These images present new opportunities to explore landcover mapping and wildlife habitat modeling at finer scales. These fine scale images may be particularly useful for mapping rangeland vegetation composed of smaller life forms (e.g. shrubs and grasses rather than trees) and habitat for wildlife species in these rangelands. The pygmy rabbit (Brachylagus idahoensis) is a species of special concern in the Great Basin shrub steppe and adjacent mountain ranges in the western US. Its primary habitat is in the sagebrush steppe dominated by plant communities that include big sagebrush (Artemisia tridentata) and rabbit brush (Chrysothamnus spp.), however its selection for levels of shrub cover and spatial arrangement of shrubs is not well known. This study evaluated selection for landscape structure by pygmy rabbits at two study sites in the Lemhi Valley of east central Idaho across a series of extents and landscape metrics. Specifically the landscape composition and spatial patterns of shrub cover within 6, 60, and 120-m buffers around known pygmy rabbit locations were quantified on a map with 3-m pixel resolution and four shrub canopy cover classes (0-5%, 5-15%, 15-25%,and >25%). A sum rank nonparametric test wasused to evaluate habitat selection in proportion to different shrub cover classes, patch shape, evenness, and patch interspersion. Selection by pygmy rabbits differed between study sites and among buffer sizes. Results indicated that pygmy rabbits were selecting habitat based on landscape structure. Specifically, the rabbits showed selection for areas of 15-25% shrub cover within the smallest buffer size, and interspersion of cover levels across the landscape as indicated by the largest buffer size.  Furthermore, it was demonstrated that fine scale remote sensing and landscape pattern analysis are useful  tools in assessments of habitat selection by pygmy rabbits at multiple scales.”