Distribution, Abundance, and Seasonality
The pronghorn is a fairly common resident of northeastern California, and locally common in Mono Co. Since 1982, the California Department of Fish and Game has translocated pronghorns captured in northeastern California to Kern, San Luis Obispo, and San Benito cos., where small populations have become established. The pronghorn is found only in sagebrush, low sage, bitterbrush, grassland, pinyon-juniper, riparian, and alkali desert scrub habitats. Numbers in northeastern California have increased considerably in recent years; there were nearly 6000 in 1978 (Pyshora 1978, Salwasser and Shimamoto 1979).
Specific Habitat Requirements
Feeding: Forbs are the most important forage during summer. Browse is an important forage in all seasons, and is critical in winter (Ferrel and Leach 1950, Pyshora 1977). Several species of sagebrush are the most important browse, followed by bitterbrush and other shrubs (Pyshora 1977). Grass is used to a lesser extent than forbs and browse, but may be important spring forage (O'Gara 1978, Kitchen and O'Gara 1982). Use of alfalfa and other cultivated plants in California has been low, but may be increasing (Salwasser and Shimamoto 1979).
Cover: Pronghorns rely on speed, and ability to detect moving predators at long distances, to escape in open habitats. Also use shrubs and rolling topography for cover.
Reproduction: Low rolling terrain and open vegetation used for reproduction.
Water: Free water apparently necessary. The amount of water consumed varies inversely with the quantity and succulence of green vegetation consumed. Autenrieth (1978) reported daily consumption rates of 0.34 I (0.36 qt)/day in May, and 4.5 I (4.8 qt)/day in August.
Pattern: Pronghorns prefer low, rolling topography in open grassland and sagebrush communities. Optimal habitat is roughly 40-60% grass, 10-30% forbs, and 5-20% shrub cover (Sundstrom et al. 1973, Autenrieth 1978, Yoakum 1978). Low vegetation of up to 38 cm (15 in) is preferred.
Species Life History
Activity Patterns: Active yearlong. Mostly crepuscular, but may be active day or night. Peak feeding time is shortly after sunrise and shortly before sunset (Kitchen 1974, Kitchen and O'Gara 1982).
Seasonal Movements / Migration: Pronghorns may migrate between summer and winter ranges. May move up to 150 km (93 mi) between ranges in California.
Home Range: Winter herds contain all ages and sexes, and may number 2000. Groups of 600 have been sighted in California (Pyshora 1977). In spring, winter herds break up into smaller groups. Young males forn bachelor herds of 2-40, and females may be found in groups of 5-20. Home ranges are extremely variable, depending on habitat, year, and location. Yoakum (1978) reported daily movements of 0.1-0.8 km (0.06-0.5 mi) in spring and summer, and 3.2-9.7 km (1.9-5.8 mi) in fall and winter. During periods of extreme winter weather may restrict activity to very small areas.
Territory: On the summer range, dominant males hold widely spaced territories of about 0.2-5.2 km? (0.06-2.0 mi?) (Kitchen 1974, O'Gara 1978). Territories usually contain some water. Females are attracted to territories for mating.
Reproduction: Polygynous, mating from mid-September to early October. Bucks maintain harems of up to 15 does (Yoakum 1978). Gestation about 252 days. Twins generally born in spring, single births are less common. Young precocial, and weaned during rut. At this time, small herds of fawns may be observed. Females generally mate first time as yearlings. Males, though sexually mature, usually do not mate as yearlings because of inability to hold a territory.
Niche: Compete with domestic sheep, feral burros and wild horses. Excessive use by these species will reduce carrying capacity of range for pronghorns. Potential predators include bobcats and coyotes. Fences, and other barriers associated with human activities, not designed to allow them to pass, are detrimental to pronghorns.
Sources & References
California Department of Fish and Game, 1999.
Autenrieth, R. 1978. Guidelines for the management of pronghorn antelope. Biennial Pronghorn Antelope Workshop Proc. 8:472-526. Ferrel, C. M., and H. R. Leach. 1950. Food habits of the pronghorn antelope of California. Calif. Fish and Game. 36:21-26. Kitchen, D. W. 1974. Social behavior and ecology of the pronghorn. Wildl. Monogr. 38:1-96. Kitchen, D. W., and B. W. O'Gara. 1982. Pronghorn (Antilocapra americana). Pages 960- 971 in J. A. Chapman and G. A. Feldhamer, eds. Wild mammals of North America. Johns Hopkins Univ. Press, Baltimore, MD. 1147pp. O'Gara, B. W. 1978. Antilocapra americana. Mammal. Species. No. 90. 7pp. Pyshora, L. 1977. The pronghorn antelope in northeastern California. Calif. Dep. Fish and Game, Wildl. Manage. Branch, Sacramento. Adm. Rep. No. 77-2. 46pp. Pyshora, L. 1978. California state report. Proc. Biennial Pronghorn Antelope Workshop. 8:8-14. Salwasser, H., and K. Shimamoto. 1979. Some aspects of pronghorn ecology and management in northeastern California. Cal-Neva Wildl. 1979:1-10. Sundstrom, C., W. G. Hepworth, and K. L. Diem. 1973. Abundance, distribution and food habits of the pronghorn. Wyo. Game and Fish Comm. Bull. No. 12. 61pp. Yoakum, J. D. 1978. Managing rangelands for the American pronghorn antelope. Biennial Pronghorn Antelope Workshop 8:321-336.
California Animal Facts | California's Wildlife