The swift fox (Vulpes velox) has traditionally been associated with short and mixed-grass prairie throughout the Great Plains. Recent declines in swift fox numbers and range in the northern Great Plains has been attributed to reduction in habitat due to conversion of range and prairie lands to row-crop agriculture. In western Kansas, however, swift fox make use of large, homogeneous areas of cropland. In 1994 I initiated a telemetry study to examine abundance, and mortality of swift foxes on cropland and rangeland in western Kansas. Additionally, I examined morphological characteristics to look for differences in body size attributable to habitat and gender.

No difference was found in abundance, survival time, or number of mortalities between foxes living on rangeland and cropland. Overall, 33% of swift fox deaths were attributed to coyote predation, 24% to vehicle collisions, and 43% to non-traumatic causes. The ratio of traumatic and non-traumatic deaths differed between foxes resident on rangeland and cropland; the likelihood of death from traumatic causes was greater on rangeland (82%) than cropland (30%), but that from non-traumatic causes was greater on cropland (70%) than rangeland (18%). Swift fox were found to be sexually dimorphic with male foxes being larger than female foxes. Male foxes had larger body mass, body length, ear length, hind-foot length, and condition index (mass/body length) scores. In addition, foxes living on rangeland were morphologically different from those living on cropland. Foxes on rangeland had higher body mass and condition index scores than cropland foxes. Lower mass and condition scores, coupled with greater mortality from non- traumatic causes, suggests a link between condition and mortality for foxes living on cropland.

Differences in traumatic and non-traumatic deaths on the two habitats may be explained by reduced fitness of cropland foxes and an increase risk of traumatic deaths for rangeland foxes due to higher coyote densities and increased risk of vehicle collisions.