Report of endangered species studies on Naval Petroleum Reserve No. 2, Kern County, California

Technical Report · Tue Sep 01 04:00:00 EDT 1987

OSTI ID:5548779

O'Farrell, T P; Warrick, G D; Mathews, N E; Kato, T T

Between 1983 and 1986 the size of the population of San Joaquin kit foxes (Vulpes macrotis mutica) on Naval Petroleum Reserve No. 2 (NPR-2), Kern County, California, was estimated semiannually using capture-recapture techniques. Although summer population estimates varied between 222 in 1983 and 121 in 1986, and winter estimates varies between 258 in 1984 and 91 in 1983, the population appeared to remain relatively stable at an apparent norm of 165. Kit foxes were abundant even in the intensely developed areas, and numbers and densities (1.12 to 2.49/sq mile) were consistently higher on NPR-2 than on neighboring NPR-1. The percentage of adult vixens that successfully raised pups was 55%, average litter size was 4.0 +- 0.0, and the sex ratio (M:F) of 25 pups was 1:1.5. Most (45.2%) foxes were killed by coyotes (Canis latrans), vehicles killed 6.4%, and 6.5% died of other causes. A cause could not be determined for 41.9% of the deaths. There was a general increase in coyote visitation rates at scent stations, but kit fox visitation rates generally decreased. Kit fox indices were consistently higher on NPR-2 than on NPR-1. Approximately 15% of the kit foxes on NPR-2 dispersed an average of 2.2 +- 0.2 miles. Average dispersal distance did not differ between the sexes. The longest dispersal was 6.9 miles. Proportionately more male than female pups dispersed. Remains of lagomorphs (jackrabbits and cottontails) and kangaroo rats had the highest frequency of occurrence in scats. Frequency of occurrence of lagomorph remains was greater in developed than in undeveloped habitats. Proportions of lagomorph remains increased and kangaroo rat remains decreased between 1983 and 1984. 62 refs., 9 figs., 24 tabs.

• Research Organization: EG and G Energy Measurements, Inc., Goleta, CA (USA). Santa Barbara Operations
• DOE Contract Number: AC08-83NV10282
• OSTI ID: 5548779
• Report Number(s): EGG-10282-2189; ON: DE88004705
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020900 -- Petroleum-- Environmental Aspects
510500* -- Environment
Terrestrial-- Site Resource & Use Studies-- (-1989)
54 ENVIRONMENTAL SCIENCES
AGE DEPENDENCE
ANIMALS
CALIFORNIA
DISTRIBUTION
ECOSYSTEMS
ENDANGERED SPECIES
FEDERAL REGION IX
FOXES
GEOLOGIC DEPOSITS
HABITAT
LAND USE
MAMMALS
MANAGEMENT
MINERAL RESOURCES
MORTALITY
NAVAL PETROLEUM RESERVE
NESTS
NORTH AMERICA
PETROLEUM DEPOSITS
PREDATOR-PREY INTERACTIONS
RESERVES
RESOURCES
SPATIAL DISTRIBUTION
TERRESTRIAL ECOSYSTEMS
USA
VERTEBRATES
WILD ANIMALS