Sources and rates of mortality of the San Joaquin kit fox, Naval Petroleum Reserve No. 1, Kern County, California, 1980-1986. [Vulpes macrotis mutica]
Sources and rates of mortality of the San Joaquin kit fox (Vulpes macrotis mutica) were studied from 1980 to 1986. Of 270 foxes radiocollared, 225 were recovered dead. Of the 225 recovered dead 53.8% (121) were killed by predators, 10.7% (24) were killed by vehicles, 4.4% (10) died from causes other than predation, and 31.1% (70) died from unknown causes. Contingency-table analysis was used to assess the relationship between cause of death and sex, age class (juvenile and adult), habitat type (undeveloped and developed), and year of death (1980-1986). More adults in undeveloped habitat were killed by vehicles than were juveniles; more female juveniles in developed habitat were killed by vehicles than female adults; more juveniles were killed by vehicles in developed habitat than in undeveloped habitat; and more adults in developed habitat were killed by predators in later years of the study than in early years. Over 90% of the foxes collared as juveniles were recovered in their first or second year. Fourteen mortality rates based on age class and year of death were estimated using maximum-likelihood estimation. Mortality rates were higher for juvenile foxes (x-bar = 0.74) than for adult foxes (x-bar = 0.52). For foxes collared as juveniles, there was no significant difference in survival between the two habitat types or between the sexes. Mortality of adults increased between 1980 and 1986. Because coyote predation was a major cause of kit fox mortality the coyote control program implemented in 1985 should be continued and its effectiveness should be evaluated by continued monitoring of kit fox, coyote, and prey populations.
- Research Organization:
- EG and G Energy Measurements, Inc., Goleta, CA (USA). Santa Barbara Operations
- DOE Contract Number:
- AC08-83NV10282
- OSTI ID:
- 6478597
- Report Number(s):
- EGG-10282-2154; ON: DE87012332
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Terrestrial-- Site Resource & Use Studies-- (-1989)
54 ENVIRONMENTAL SCIENCES
AGE DEPENDENCE
ANIMALS
CALIFORNIA
DATA
ENDANGERED SPECIES
EXPERIMENTAL DATA
FEDERAL REGION IX
FOXES
GEOLOGIC DEPOSITS
INFORMATION
MAMMALS
MINERAL RESOURCES
MORTALITY
NAVAL PETROLEUM RESERVE
NORTH AMERICA
NUMERICAL DATA
PETROLEUM DEPOSITS
PREDATOR-PREY INTERACTIONS
RESERVES
RESOURCES
USA
VERTEBRATES