Causes and Rates of Mortality of Swift Foxes in Western Kansas

Abstract

Knowledge of mortality factors is important for developing strategies to conserve the swift fox (Vulpes velox), a species being considered for listing under the Endangered Species Act, but available infor- mation about swift fox mortality is inadequate. We used radiotelemetry techniques to examine the magnitude and causes of mortality of swift fox populations in 2 study areas in western Kansas. One study area was predominantly cropland, the other rangeland. Mortality rates, calculated using Kaplan-Meier niques in a staggered entry design, were 0.55 ? 0.08 ( estimation tech- by coyotes (Canis latrans) was the major cause of mortality for adult and juvenile swift foxes in both study areas, and vehicle collision was an important mortality factor for juveniles in the cropland study area. No mortality was attributed to starvation or disease.