USING SURVIVAL OF RODENTS TO ASSESS QUALITY OF PRAIRIE HABITATS

Abstract

Estimates of abundance commonly are used for assessing quality of wildlife habitat. However, disparities between abundance and fitness parameters make the utility of abundance for predicting quality of habitat questionable. We used survival of rodents and rates of capture to assess quality of habitat in greasewood scrub and sandhill prairie habitats at the United States Army Pueblo Chemical Depot, Pueblo, Colorado. Only the Ord's kangaroo rat (Dipodomys ordii) and the North American deermouse (Peromyscus maniculatus) were captured and recaptured enough to warrant statistical analysis. Apparent survival was modeled using temporal and seasonal patterns, vegetation cover, type of habitat, abundance of sympatric rodents, and abundance of grasshoppers. The most parsimonious models for survival of Ord's kangaroo rat incorporated abundance of bare ground at trapping sites, while the most parsimonious models for survival of North American deermice included amount of shrub cover at trapping sites. Although rates of capture for Ord's kangaroo rats and deermice were different between habitats, rates of survival did not differ between habitats. Suggestions that particular xeric-shrub habitats provide better quality of habitat for deermice and kangaroo rats should be framed using the relationship between rates of survival and abundance, instead of relying on abundance or rates of capture.