CAUSES AND RATES OF MORTALITY OF SWIFT FOXES IN WESTERN KANSAS

Knowledge of mortality factors is important for developing strategies to conserve the swift fox (Vulpes velox), a species being considered f or listing under the Endangered Species Act, but available information about swift fox mortality is inadequate. We used radiotelemetry techn iques to examine the magnitude and causes of mortality of swift fox po pulations in 2 study areas in western Kansas. One study area was predo minantly cropland, the other rangeland. Mortality rates, calculated us ing Kaplan-Meier estimation techniques in a staggered entry design, we re 0.55 +/- 0.08 ((x) over bar +/- SE) for adult and 0.67 +/- 0.08 for juvenile swift foxes. We did not detect differences between study are as in mortality rates for adults or juveniles. Predation by coyotes (C anis latrans) was the major cause of mortality for adult and juvenile swift foxes in both study areas, and vehicle collision was an importan t mortality factor for juveniles in the cropland study area. No mortal ity was attributed to starvation or disease.