General Distribution
The Bureau of Land Management manages approximately 5,000 wild burros on federally owned public
lands in the western United States. A total of 196 wild horse and wild burro management areas are
located in Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, and
Wyoming. There are 22 wild horse and burro herd management areas located throughout southern
California (Bureau of Land Management 2000).
The USDA Forest Service administers 36 wild horse or burro territories located in Arizona, California,
Nevada, New Mexico, Oregon, and Utah (USDA Forest Service 2001). The USDA Forest Service
coordinates with the Bureau of Land Management in the management of adjacent territories as well as in
the removal of wild burros in excess of the territory capacity.
A burro population of approximately 50–60 animals (Eliason pers. comm.) currently inhabits the eastern
San Bernardino Mountains at the northeastern corner of the San Bernardino National Forest. This
population is organized into multiple loose herds that reside in a 35,000-acre (14,164-hectare) wild burro
management area east of Baldwin Lake. Systematics
Burro (Equus asinus) is also commonly known as ass or donkey. It is generally believed that the present-day
burro originated from African wild asses. Three geographical races of wild asses are recognized in
Africa: one in northern Africa, one in northeastern Africa, and one in Somalia (Zarn and others 1977).
However, it is unclear from which race the present-day North American form derived.
Domesticated burros were introduced into the United States by a Spanish colonizer around 1599.
Originating in New Mexico, burros spread through the western United States and eastward to Missouri.
Burros proved to be reliable pack animals that could travel long distances surviving on desert
vegetation. Until the nineteenth century, burros were considered valuable property and probably did not
exist in the wild. As the mining boom began to decline and the improvement of roads allowed for better
transportation, burros were released into the wild or abandoned. By the last quarter of the nineteenth
century, wild burros became widely distributed throughout the western United States (Zarn and others
1977). Habitat Requirements
Wild burros range through a wide variety of desert habitats but need to be within 10 miles (16
kilometers) of drinking water (Royo 1997). Burros are primarily found in arid desert-montane habitats.
They are opportunistic herbivores that roam across large areas in search of food resources (Stephenson
and Calcarone 1999). Reproduction
Female burros, or jennies, reach sexual maturity at about 3 years of age and may continue to reproduce
for 30 years. Although jennies are polyestrous and could breed in more than one season, reproduction is
generally restricted to particular breeding periods. Female wild burros give birth to one foal each year.
Gestation lasts about 12 months but can range from 11 to 13 months. In Mississippi, conception rates
were highest in the summer and fall (Zarn and others 1977). Daily/Seasonal Activity
Burros are generally diurnal but reduce their activities during hot summer months, when they forage
mostly at night and in the early morning. Seasonal movement patterns are recognized in wild burro
herds. They tend to wander farther in the winter, roaming 3–6 miles (5–10 kilometers) from water.
During the summer, most of the population remains within 2 miles (3 kilometers) of water (Zarn and
others 1977). Diet and Foraging
Studies of burros from Cottonwood Canyon of Death Valley showed that forbs comprised about
65 percent of the spring diet, and browse comprised more than 75 percent of the fall diet (Zarn and
others 1977). They are opportunistic herbivores, feeding on a variety of plants and grasses (Stephenson
and Calcarone 1999). Although these plant materials provide some moisture, wild burros must also have
nearby sources of drinking water throughout the year. They can usually be seen foraging for food
during daytime, except during the summer, when they forage only at night and in the early morning
(Royo 1997). Territoriality/Home Range
The size of a burro's home range is variable and dependent on the proximity of four essential habitat
requirements: grazing area, shelter, water, and shade. When all these requirements are close together,
the size of the home range is smaller than when they are widely dispersed. Female home ranges vary
from 320 to 4,600 acres (130 to 1,643 hectares). Male home ranges are generally larger, varying from
576 to 10,000 acres (233 to 4,047 hectares) (Zarn and others 1977).
Some males hold mating territories but usually do not prevent other males from entering their territory
as long as they do not interfere with mating activities. Males will defend females in estrous when they
are near the boundary of the territory (Zarn and others 1977). Predator-Prey Relations
No information is available on predation of wild burros. Mountain lion is the only predator that occurs
within the range of the burro that is capable of killing an adult. Coyotes could potentially kill newborn
or young burros that have been left unprotected (Zarn and others 1977). Literature Cited
Bureau of Land Management. 2000. National wild horse and burro program. [Online]. Available: http://
www.blm.gov/offline/.
Bureau of Land Management. 2002. Public Land Statistics 2002. [Homepage of Bureau of Land
Management], [Online]. Available: http://www.blm.gov/natacq/pls02/.
Hill, J. (Ed.). 1997. Burros wear out their welcome in California. CNN interactive, Earth story
page. [Homepage of CNN], [Online]. Available: http://edition.cnn.com/EARTH/9703/16/burros/.
Royo, A.R. 1997. Wild burro: Equus asinas. [Homepage of Desert USA], [Online]. Available: http://
www.desertusa.com/magjan98/jan_pap/du_wildburro.html.
Stephenson, J.R.; Calcarone, G.M. 1999. Southern California mountains and foothills assessment:
Habitat and species conservation issues. General Technical Report GTR-PSW-172. Albany, CA: Pacific
Southwest Research Station, Forest Service, U.S. Department of Agriculture.
USDA Forest Service. 1998. Big Bear burro update. Press release, San Bernardino National Forest, San
Bernardino, CA.
USDA Forest Service. 2001. Wild horse and burro territories. [Homepage of USDA Forest Service],
[Online]. Available: http://www.fs.fed.us/rangelands/ecology/wildhorseburro_territories.html.
Zarn, M., Heller, T.; Collins, K. 1977. Wild, free-roaming burros, status of present knowledge. Bureau
of Land Management and USDA Forest Service - Technical Note.
Information gathered from California DFG - California Interagency Wildlife Task Group
