Mojave National Preserve - Burro

The burro ( Equus asinus ) was introduced to North America in the 16th century by Spanish explorers. These burros were descendants of the Nubian and Somali wild asses of northeastern Africa, which were domesticated for use as beasts of burden. Strong and hardy, these animals were used extensively by early minors and other explorers of the western United States. Feral burro populations became established as a result of domestic escapees and animals intentionally turned loose after they were no longer needed.

Burros have thrived in the arid southwest and today pose a threat to native ecosystems. One concern is that the burros have a negative impact on springs and riparian areas. An adult burro drinks an average of 22 liters (5 gallons) of water per day, as opposed to native bighorn sheep, which drink an average of 3.8 liters (1 gallon) of water per day. Burros are also known to pollute water sources with feces and urine, and can eliminate native vegetation through overbrowsing.

A census in 1996 estimated 1,650 burros in the main unit of the Preserve (excluding the Clark Mountain unit.) In the five years following that census, almost 3,000 burros were removed using a combination of water trapping and helicopter-assisted roundups. These burros were transferred to several facilities to be adopted or sold as pets. However, burros are prolific breeders and herd sizes can increase at rates of 19 to 29 percent per year. There are still at least an estimated 250 burros in the Preserve and water trapping will continue in 2002. In addition, the Preserve is searching for funds to facilitate additional helicopter roundups, as well as to begin fencing portions of the boarder.