Swift fox use of black-tailed prairie dog towns in Northwest Texas

Biologists have suggested that prairie dog (Cynomys ludovicianus) towns provide important habitat for several prairie species including swift foxes (Vulpes velox). To examine this issue for swift foxes, we radiocollared and monitored 72 swift foxes in areas occupied by prairie dogs on the Rita Blanca National Grasslands and on fragmented private ranches in northwest Texas from January 2002 to April 2004. We overlaid swift fox locations on vegetation maps and found that swift foxes used prairie dogs towns proportionately less than expected (P < 0.001) in 5 of 6 comparisons based upon availability at both study sites. In one comparison swift foxes used prairie dog towns as expected. We also mapped swift fox den locations and found that den sites were located in prairie dog towns (2 of 106 den sites on national grasslands and 2 of 87 on private ranch for all years pooled) as expected based upon availability (P = 0.54 and P = 0.34). Previous research in these areas of Texas indicated that prairie dogs were a minor component of swift fox diet (<2%). Prairie dog towns do not appear to provide important habitat for swift foxes in northwest Texas or other similar sites because prairie dogs are not a significant source of food for swift foxes, because swift foxes generally avoid prairie dog towns during their normal activities, and because swift foxes only den in prairie dog towns in relation to their availability.