Habitat, soils, and den use of San Joaquin kit fox (Vulpes velox macrotis) at Camp Roberts Army National Guard Training Site, California

by: Elizabeth A. Reese, William G. Standley, and William H. Berry
ABSTRACT: Den use patterns, den characteristics, and effects of military training on dens were studied for San Joaquin kit foxes (Vulpes velox macrotis) at Camp Roberts Army National Guard Training Site, California. Ninety-four radiocollared kit foxes used 1059 dens and 334 buildings as shelter from December 1988, through September 1991. There were 1001 (95%) earthen dens, 57 (5%) culverts, and one den in a hollow log. Den entrance dimensions were measured for single entrance dens; the average height was 20 cm, and the average width was 21 cm. Most dens had two to five den entrances, and only 36% of dens found showed sign of fox activity. Dens were found at elevations between 161 and 351 m. The average slope of dens found on hillsides was 19 degrees, and most dens faced the western quadrant. Dens were found over much of the post except the steep southwest portion. More kit fox dens were located in grassland and low to medium density oak woodlands than expected, and fewer dens were located in developed areas and medium to high density oak woodlands than expected. Denning range size was calculated for 16 foxes that were radiocollared at least one year and that were found using only earthen and culvert dens. The average denning range size was 171.0 +/- 24.0 ha. There was no significant difference in male and female average denning range sizes. When buildings used as shelter were included in denning range sizes, there was no significant difference in average denning range size between developed and undeveloped areas. Foxes used 26 of 36 available soil series, and dens were not distributed proportionally among the 36 soil series. Kit fox dens were typically found in well drained soils. Few den entrances were destroyed by miltary training exercises.
1992. U. S. Dept. of Energy Topical Report, EG&G/EM Santa Barbara Operations Report No. EGG 10617-2156. 36 pp. Reprints are available from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Road, Springfield, VA 22161.
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