| Due to severe reductions in their distribution and numbers, the swift fox (Vulpes velox) was classified as warranted, but precluded as a threatened species by the U.S. Fish and Wildlife Service from 1995 to 2001. Several factors were likely responsible for the decline of the swift fox in the western Great Plains, including habitat loss and competition with coyotes (Canis latrans). From 1998 to 2001, we radio-collared and monitored 88 swift foxes and 29 coyotes at 2 study sites in northwestern Texas to investigate the ecology and relationships of both species. Initial results suggested that higher coyote numbers on site 1 resulted in lower survival, lower density, and lower recruitment of swift foxes compared to site 2. To test this hypothesis, we experimentally removed coyotes on site 1 during the final year of the study. Subsequently, swift foxes had increased survival, increased density, increased recruitment, and exhibited a source population due to lower predation by coyotes. We also found that high mortality from coyote predation affected the spatial distribution, mating system, and group structure of swift foxes. These results indicate that high coyote numbers can suppress swift fox populations due to heavy predation.; To determine if habitat loss also negatively affected swift foxes, we examined habitat selection of swift foxes at 2 spatial scales on site 2, which was comprised of short-grass prairies grazed by cattle (46% of area), non-native (CRP) grasslands that were ungrazed (23%), and agricultural fields (31%). Habitat use was similar at both spatial scales, as swift foxes exhibited a strong preference for short-grass prairies and nearly complete avoidance of CRP grasslands and agricultural fields. These results indicate that swift foxes are habitat specialists, thus protection of native short-grass prairies might be necessary for their long-term existence.; We documented that the social organization of swift foxes was based entirely on female territories, as adult males emigrated after adult female deaths, but not vice versa. A female-based social organization, previously unknown among canids, likely evolved in swift foxes from the reduced importance of food provisioning by males. |
