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A Sonoran Pronghorn is released back out into the wild during the annual capture and release at the Kofa Wildlife Refuge near Yuma, Arizona, Dec. 19, 2023. In 1967 the Pronghorn was listed in as an endangered species under the Endangered Species Preservation Act, in 2002 the population plummeted to only 21 Pronghorn in the U.S. and for over two decades there has been a federal collaborative effort to maintain the health, safety and security of the growing species. (U.S. Marine Corps photo by Cpl. Jade K. Venegas)

Photo by Cpl. Jade Venegas

Bucks and Does: Saving the Sonoran Pronghorn for over two decades

8 Jan 2024 | Cpl. Jade Venegas Marine Corps Air Station Yuma

YUMA, ARIZONA – In a collaborative effort to maintain the health, safety and security of the Sonoran Pronghorn, a number of federal animal organizations conducted their annual capture and release of the Sonoran Pronghorn at the Kofa Wildlife Refuge near Yuma, Arizona, Dec. 19, 2023.
The Sonoran Pronghorn was first listed as an endangered species in 1967 under the Endangered Species Preservation Act and grandfathered into the endangered species list in 1973.
In 2002, an extreme long-term drought and human impact to the landscape plummeted the population to an extreme low of 21 Pronghorn in the United States. This spurred wildlife biologists to action in attempts to save the Sonoran Pronghorn, which have extended all the way into the current day.
The Sonoran Pronghorn can be found in the east and west side of the Barry M. Goldwater Mountain Ranges which are managed by the U.S. Marine Corps and Air force. They can also be found at Organ Pipe National Monument. Every year they are captured, provided medical attention and supervised at the Kofa and Cabeza Prieta Wildlife Refuges before they are let out into the wild again.
Randy English, the Range Management Conversation Program Manager at Marine Corps Air Station (MCAS) Yuma, Arizona, explains that for over two decades, various federal agencies have assisted in the success of the slowly recovering species. He said, “You need collaboration between the agencies because the Pronghorn actually cover the property of all these agencies, and it takes a collective effort to actually manage them and make the population increase.”

During the capture and release, the Pronghorns are captured and put into a boma, which is a small enclosure that helps gather them in even small groups. Researchers and biologists then carefully enter the boma with a net to capture the Pronghorn safely without harming it or those handling them.

“It’s organized chaos. There is a whole group of people going into the boma and each one of those people has a very specific job,” says Jeremy Pennell, a wildlife biologist at MCAS Yuma.

Everyone works as a team entering the boma allowing the Pronghorn to be captured in the net. There are four different roles in the capture process. The first belongs to those holding the nets that catch the Pronghorn. Another role is that of the “Wallflowers,” who are instructed to run along the inside of the boma to keep the Pronghorns from jumping off the walls and prevent them from injuring themselves. Once they are captured in the net, the “Muggers” come in to blind fold the Pronghorn and unsecure it from the net. Lastly, the veterinarians can come in to provide medical aid, gather blood samples, and monitor the animals during the event.

“The entire capture event is monitored by a team of talented wildlife veterinarians and technicians,” said Jeremy.

The veterinarians and technicians are from the Arizona Game and Fish Department, they monitor the temperature of the Pronghorns to ensure they don’t go into hyperthermia due to the stress of the capture. All the animals receive a variety of injections such as dewormers, vitamins, vaccines for rabies and blue tongue virus and retrieving blood samples. and give blood samples.

Randy explains, “They draw blood samples so that they can check the health of the animals, check for parasites and do some DNA analysis.”

Some of the newly released Pronghorn are fitted with a very high frequency or GPS collar that allow researchers to track them and view how they fit into their new habitat. “The data provides insight on how the newly released Pronghorn are integrating into their new habitat and their new home. It allows us to see if maybe they are wandering into areas where we haven’t seen Pronghorn before and if they're utilizing that habitat,” said Jeremy.

Once all the Pronghorn are attended to by the veterinarians they are either released back into the wild or transported to another location where the Pronghorn can spread the population to ensure the safety and security of the species.

In this case they were transported to a sublocation at the Yuma Proving Ground (YPG). From there biologists can monitor them and assess for injuries that may have occurred during transport before they are released into the wild.

“It helps spread the population out so that if there’s any local area activities or incidents where the animals may be affected, having them spread out over a wider geographical range actually helps to ensure the population as a whole can be maintained,” said Randy. “Essentially you don’t want to put all your eggs in one basket. So, we have multiple baskets across the countryside to ensure that the population as a whole is healthy.”

Recovering from a total population of just 21 Pronghorn in 2002 to now where there are well over 400 in the United States is a huge accomplishment.

Randy has worked in the conversation field for over two decades, he was initially at YPG from 2002 to 2010 and has been with MCAS Yuma since then. He said, “just to be here from the time that the population was at a really low level to see it recover over the years. Thanks to all the work of all the agencies has just been great, nobody would have expected that we would have done as well as we have.”

“The numbers kind of speak for themselves. It’s obviously having a great impact we’re learning a lot more about the Pronghorn as we reintroduce them in these new areas. Pronghorn exist on the landscape in more areas in their historic habitat than they have in many decades,” said Jeremy. “The future is looking brighter. There is still a lot of work to be done and we look forward to eventually getting this species down listed and then delisted.”

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