Status and long-term use of artificial escape dens by swift foxes in Northwest Texas

Abstract

Swift foxes (Vulpes velox) occurred in 79 counties in Texas during the early 1900s; they currently only inhabit the two most northwestern counties, Dallam and Sherman. The major cause of swift fox mortality is attributed to coyote (Canis latrans) depredation. During 2002 to 2004, 191 artificial escape dens were established on the Rita Blanca National Grassland (RBNG), the Kiowa National Grassland (KNG), and a private ranch to aid swift foxes in escaping from coyotes. Swift foxes used escape dens through 2004 and their survival appeared to increase. We initiated a study in 2012 to determine the physical condition and use of these artificial dens by swift foxes. We found 72.8% of these artificial dens had become unusable by swift foxes because of obstructions within dens and/or complete burial by soil. Ten artificial dens sustained physical damage, seven had cracks along the pipe, two had crushed entrances when apparently stepped on by cattle, and teeth marks on one den suggested damage by a predator. We found evidence of swift fox use at only one artificial den in RBNG. Swift foxes had used artificial escape dens when they were established. It appears that long-term use of escape dens by swift foxes will require periodic maintenance to clear obstructions that interfere with their use.