Sonoran Pronghorn in El Pinacate Biosphere Reserve

The Sonoran pronghorn (Antilocapra americana sonoriensis) is the smallest of five subspecies. It is endemic to the Sonoran desert ecoregion with a historical distribution shared by the state of Sonora in Mexico and Arizona in the United States.

In Sonora, its historical distribution in Mexico ranges from the borderline and the El Pinacate and Gran Desierto de Altar Biosphere Reserve to the valleys near Kino, passing through the coast of the Gulf of California.

Altought, currently it only reaches the territory near Caborca, so it has lost two thirds of its original distribution.

Back in the 1993, El Pinacate and Gran Desierto de Altar Biosphere Reserve was decreed and since then it has been managed by the National Commission of Protected Natural Areas also known as CONANP. This is one of the largest protected areas in Mexico with ​​714, 566 hectares of which only 22% is considered as suitable habitat for the sonoran pronghorn.

Habitat Fragmentation

The entire Sonoran pronghorn population was once connected and had a continuous flow of individuals until the seventeenth century, but its habitat has been fragmented by fences to retain livestock, development of agriculture, roads, and barriers along the border between Mexico and the United States (US Fish and Wildlife Service, 2016).

This fragmentation of the habitat has caused the division and isolation of the Sonoran pronghorn population into 4 sub-populations with a limited exchange of individuals among them. These sub-populations are located 2 in Arizona and 2 in Sonora, with the Pinacate population being an essential part of the connectivity between Arizona and the rest of the state of Sonora.

Highway No. 2 that connects the cities of Sonoyta and San Luis Rio Colorado was built in 19__ by the Secretary of Communications and Transportation. Later, in 2012, this same highway was expanded to four lanes. These roads have continuous traffic, a livestock fence on both sides and an elevation of meters above ground level. Although this stretch of road has 18 wildlife crossings that were built to facilitate the movement of species such as mule deer and bighorn sheep, there is no evidence that they are used by pronghorn.

On the other hand, highway No. 8 that connects the cities of Sonoyta and Puerto Peñasco was built in 19__ with two lanes. This road was built at the same level as the ground and also has cattle fences on both sides.

Competition for food and space

This situation has been a limitation for the mobility of the pronghorn, and can represent a high risk for the population that depends on the quality of the habitat that exists each year in order to survive. So the carrying capacity that the land has depends partly on the seasonal precipitation, but also on the competition for resources and space with other herbivores that are present in the area, mainly cattle. Although pronghorn can interact with cattle, it has also been documented that pronghorn can avoid areas with high density of cattle.

As part of our research to monitor and document the Sonoran pronghorn, we have set up camera traps to obtain photographs of the Sonoran pronghorn and thus obtain valuable information continuously throughout the year, which would be difficult to obtain otherwise without interfering with the behavior of the animals that inhabit the Reserve.

                                                                                                                                                                 Camera traps