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A band of endangered Sonoran Pronghorn at Organ Pipe Cactus National Monument/Kelly Furnas

A band of endangered Sonoran pronghorn/Kelly Furnas

Protecting The Sonoran Pronghorn From Extinction

By Kelly Furnas

With its diminutive frame and legendary skittishness, the Sonoran pronghorn is emblematic of the delicate efforts required to save an endangered species. Relegated to the desert of southwest Arizona and northern Mexico, the pronghorn fights for survival from predators and the ever-constant threat of drought that comes with living in the desert.

Yet its recovery also depends on the delicate alliance of agencies and organizations throughout the United States and Mexico. Traditional environmental agencies such as the U.S. Fish and Wildlife Service, Arizona Game and Fish Department and National Park Service have had to work alongside their counterparts in Mexico, as well as other U.S. entities such as Border Patrol and the military, whose base makes up nearly half of the pronghorn’s American habitat.

But despite international political tensions and disparate core missions of different organizations, John Hervert of Arizona Game and Fish said the positive momentum of the pronghorn’s resilience has been a tribute to the multiagency recovery team.

“It boils down to people,” Hervert said. “Whether or not people can get along and set their egos aside to some degree. If we didn't have those good working partnerships I wouldn't be too optimistic.”

A pronghorn leaving a guzzler/NPS

"Guzzlers," man-made water holes, help the pronghorn deal with drought/NPS

The optimism is backed up by numbers. A devastating drought in 2002 left about only 300 Sonoran pronghorn in the wild, including only 21 individuals in the United States. With help from a captive breeding program and active management, the numbers are now closer to 1,000. As one of the original 75 species protected by the Endangered Species Preservation Act, the Sonoran pronghorn can be seen both as a success story and a harbinger of how fragile progress can be.

Perhaps the biggest complicating factor for the pronghorn is the fact its habitat crosses the U.S.-Mexico border. Environmental groups such as Center for Biological Diversity, Defenders of Wildlife and the Animal Legal Defense Fund have all raised alarm about the effect of President Donald Trump’s border wall on the pronghorn and other species in the area. In a motion for an injunction filed in August, the groups specifically listed migration as key to the species’ survival.

“The erection of impenetrable bollard walls will truncate the crossborder movement of the endangered Sonoran pronghorn, ferruginous pygmy owl, and Bighorn sheep, which rely on connectivity to other adjacent populations for genetic variability and their continued survival,” the motion said.

State and federal biologists don’t necessarily dismiss those concerns, but they admit most of the damage to crossborder migration has already been done by Mexican Highway 2, which travels east-west along much of the Mexico-Arizona border. Unlike other ungulates such as deer or elk, pronghorns are notorious for being unwilling to cross highways.

Stephanie Doerries, a biologist with the U.S. Fish and Wildlife Service, recounted a single radio-collared buck in 2008 being recorded as crossing the highway several times, noting the crossings in place for pronghorn are underpasses and “pronghorn aren't really big on underpasses. 

But the effects of crossborder migration on biological diversity need further study, Doerries said. She is currently working with Mexican biologists gathering fecal samples to determine genetic structures of the different populations of pronghorn.

“There are still a lot of questions about how much crossing do you need to have for there to be some level of genetic connectivity,” Doerries said. “You might just need one individual every couple years for there to be some connectivity. That's a question we're still trying to answer with Sonoran pronghorn.”

The study is just one of a multitude of collaborations that U.S. and Mexican biologists have in order to promote the survival of the fastest land mammal in North America. They coordinate biannual aerial surveys of the pronghorn’s habitat. They also work together to determine destinations for pronghorn released from captive breeding pens in Arizona 

Multiple agencies collaborate to boost the pronghorn population/Kelly Furnas

Multiple agencies collaborate to boost the pronghorn population/Kelly Furnas

Miguel Angel Grageda Garcia, who worked for three years as coordinator for natural resources at the Pinacate Biosphere Reserve in Sonora, Mexico, is now a doctoral student at the University of Arizona studying how Sonoran pronghorn are affected by human development. As a member of the Sonoran pronghorn recovery team, he said, travel to and from Mexico became increasingly difficult from 2015 to 2018 

“They have these meetings every three to six months to talk about activities done to recover the pronghorn, and some future efforts. We have been attending these meetings and sometimes it wasn't that easy because we needed to have a special permit to travel outside of the country,” he said. “Sometimes this permit needs to be obtained in advance, like two or three months before the meeting. And sometimes it is not that easy. So we had to miss some of those meetings because it wasn't easy to travel to the U.S.”

He said the political tensions between U.S. and Mexico were probably to blame for the increased hurdles in collaboration.

“I think this last year, in 2018, was when it was harder for us to be able to travel to the U.S.,” he said. “Before, we still needed to have a permit, but it didn't take so long to get it. It was always easier to do it. In the last year it was harder. Probably the change in administration may have been an issue in this situation.”

Equally complicated for the pronghorn are the effects of the Department of Homeland Security’s efforts to stem illegal traffic along the southern border. Drug smuggling routes and pedestrian border crossings through the Cabeza Prieta National Wildlife Refuge have taken their toll on an environment that used to be pristine. But Border Patrol enforcement also causes disruption to pronghorn behavior by adding stress or frightening animals away from sources of food and water — including plots of lands managed by wildlife officials with enhanced foraging opportunities.

In 2009, biologists recorded a group of does and fawns that abandoned one of these forage enhancement plots because of the high amount of Border Patrol traffic; while the does were later observed at the nearby Organ Pipe Cactus National Monument park, the fawns had died. 

Doerries said Border Patrol accounts for about 60 percent of all motor traffic on the refuge. And because pronghorn have been known to exhibit visible responses to vehicle noise more than 2 miles away, it’s a constant struggle for biologists trying to mitigate the effects 

And yet, some of the support for that mitigation is coming from Homeland Security itself. For example, when building an integrated fixed tower near Ajo, Arizona — mounted with high-tech cameras, radio, radar and other sensors to detect illegal border activity — the department earmarked $4.13 million specifically for Sonoran pronghorn conservation. That money helped fund aerial monitoring by Arizona Game and Fish, water tanks and equipment used by the National Park Service, staff and equipment at U.S. Fish and Wildlife, as well as surveys and research into the effects of human activities on pronghorn. Doerries said funding for her Ph.D. project as well as a previous position she held at Arizona Game and Fish Department were both the result of mitigation funding 

“It's really useful to keep in mind that mission,” Doerries said. “You know, there are times where certain areas of the refuge are dangerous and I'm going out in the field by myself to conduct field work. It's been nice to know that Border Patrol is nearby in a really desolate landscape where you don't have cell service. It can be useful to know there are people there.

“So many nuances to the desert here.”

Crews also try to help out the pronghorn with food/Kelly Furnas

Like Hervert, Doerries said the partnerships between the myriad agencies has been critical for the rising population of pronghorn. They said the Marine Corps and the Air Force, too, have provided funding toward recovery efforts and will regularly close down tactical ranges and targets at Luke Air Force Base if pronghorn are nearby 

“Certainly everybody doesn't think the same — but everybody's really great at recognizing let's work for the good of the pronghorn. Let’s give a little bit here,” Doerries said. “I wouldn't say everything goes smoothly all the time, but I think people generally try to take the approach that we don't have bad motives.”

That goodwill certainly extends to the recovery team members from Mexico, as well, although Hervert said his level of optimism isn’t as high for the pronghorn population south of the border.

“It gets messy down there because even land ownership is not very clear. Somebody may own the mineral rights. Somebody else might have ranching rights. And somebody else might have the rights to hunting. All on the same property,” Hervert said. “It's complex, and it's hard for the Mexican biologists to have the authority to do what needs to be done to protect habitats or to prevent fragmentation.”

The sustainability of habitat is one of the factors that come into play as the recovery team decides on an annual basis which of the four pronghorn populations should receive members from the captive breeding program. 

Arguably the most meaningful recovery effort, the captive breeding pens on the Kofa and Cabeza Prieta wildlife refuges house more than a hundred pronghorn combined. Each year, pronghorn are captured from the pens and relocated to existing populations on the refuges or in the Organ Pipe Cactus National Monument, part of the National Park System. To date, 260 pronghorn have been released from the captive breeding pens, though none of them has been transported out of the country, despite some of the original captive breeding stock coming from the Quitovac population in northern Mexico.

That might change this winter. A half-dozen pronghorn are slated to be transported to Mexico, potentially helping to connect — at least genetically — different populations of pronghorn. But the relocation, as well as the long-term management and monitoring, will require that biologists from different agencies and countries continue working together.

“Species don't know about boundaries. They just know about their habitat. They don't know what's going on with political divisions,” Garcia said. “I think it's very important for all of us biologists to work together and to have plans in the future, even if we are in different countries, different states, different protected areas. The populations sometimes are the same ones. And it should be managed in the same way.”

Kelly Furnas is a freelance writer, photographer and web developer. He teaches multimedia journalism at Elon (N.C.) University.

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Comments

This is a great little article; but, I believe a few key considerations mentioned in the article need to be hammered home.  First, pronghorm, all pronghorn, tend to be long distance migrators.  They are evolutionarily equipped with the ability to move, move fast, and move across long distances and these abilities have, of course, been integrated into their behavioral responses to threats and changing conditions, not just to predators and variations in seasonal forage availability, but also drought, climate change, and habitat disruption.  In nature, you use what you have to survive and thrive and, if there's one thing pronghorn have, it's legs and the ability to move them.  In flexible, essentially ad hoc, small groups, they access and use very large contiguous ranges, both seasonally and in response to generational changes in forage availability and safety.  They need room to roam, especially in these arid southern parts of their habitat.  Fragmenting their habitat at a time when they are already being challenged by unusual environmental stress can put these southern population segments at extreme risk.

Second, what is in the news, being inflicted on the landscape and the ranges of these southern pronghorn?  The answer is the overdressed, overslicked, but undereducated, GOP's childishly sociopathic wall.  It won't stop the bricklayers, tile workers, or strawberry pickers who need the work and know how to use a discount store reciprocating saw; but, pronghorn are famously averse to even barbed wire fences and it will stop them.  If there is one species that the wall will impact most severely, it is pronghorn.  This point needs to be hammered home at every turn.

Third, fragmenting habitat and populations increases the susceptibility of those populations to stochastic events that can eliminate needed elements of the overall gene pool.  Knowing how many Distinct Population Segments you have and how many of these represent potentially unique gene pool elements is, therefore, absolutely critical, if you intend to protect your best chances at maintaining the genetic resilience needed to confront the rapid environemntal shifts that we now face.  This point also needs to be hammered home.


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