Sonoran Pronghorn, Florin Chelaru
© Florin Chelaru

Sonoran Pronghorn

Threats to Sonoran Pronghorns

The biggest factor in the steep decline of the Sonoran pronghorn was its competition with cattle. As livestock grazed the area in increasing numbers, they left much less food for native species like the pronghorn. In the few areas where Sonoran pronghorn remain today, grazing is no longer permitted, but its numbers are extremely diminished, and several threats to the species remain.

Human Activity

The species is also sensitive to human disturbance, including military aviation activities in the Goldwater Range, and both the illegal activity in the border region and the law enforcement response. Roads, fences, railroad tracks and human development have reduced and fragmented the wide spaces they need in which to forage successfully.

Climate Change

Climate changes already underway in the southwest are threatening to push the pronghorn over the edge of extinction. Survival of fawns is determined mainly by how much rain or snow fall in the winter, and how long the drought afterwards lasts before the monsoon rains start in the summer. Winter precipitation determines the amount of food available to nursing females, and summer precipitation determines the food available to the young, newly-weaned fawns. Adult survival is also influenced by precipitation, probably because in dry conditions, animals are forced to forage in valleys where the vegetation is denser and predators are less visible.

The U.S. population very nearly died out in 2002, when a 13-month drought wiped out all but 21 animals. The U.S. Fish and Wildlife Service intervened to prevent extinction by providing water and forage and initiating a captive breeding program, as well as plans to establish a second population at nearby Kofa National Wildlife Refuge. These actions have helped the numbers creep back up, but the species’ chances of surviving climate change without continued intervention may be slim.