Joe Duhownik

PHOENIX (CN) — Led by the Center for Biological Diversity, a group of conservationists sued the U.S. Forest Service on Thursday to protect a region of the Tonto National Forest from “hundreds of unowned horses” they say threaten endangered species in the area.

Known as the Salt River herd, the horses live on the 20,000-acre allotment known as the Lower Salt River Recreation Area. In 2017, federal, state and local agencies, along with local tribes and other interested parties, committed to reducing the wild herd to only 100, to minimize its impact and protect other species that compete for forage and water. Instead, the Forest Service approved a management plan in February to reduce the population to 200 horses in the next 25 to 35 years.

Federal range scientists in 2019 concluded that the land can only reasonably support 28–44 horses. The most recent count from the Forest Service estimates the current number of horses to be between 400 and 500, but the plaintiffs estimate 600 in the lawsuit.

“This is another tragic example of Forest Service employees failing to do their jobs, obey the law and manage public lands based on science,” Center for Biological Diversity co-founder Robin Silver said in a statement. “The agency’s management plan ignores science, their own experts, facts on the ground and basic livestock husbandry. It’s senseless to try to manage 600 horses in an area where ranchers couldn’t even sustain 12 cows.”

Cattle ranching on the Lower Salt River Recreation Area was terminated in 1978 because officials determined that the land couldn't produce enough forage to support the added livestock.

Horse advocacy groups like the Salt River Wild Horse Management Group claim the horses are native to the land, having come over by boat with Spanish conquistadors hundreds of years ago. But most scientists and conservationists agree wild horse herds are actually made up of escaped or released horses from nearby ranches and tribal nations. Because they aren’t natural members of the ecosystem, conservationists say the horses damage the land and put other species at risk.

“Endangered riparian songbirds like yellow-billed cuckoos and Southwestern willow flycatchers are barely hanging on in this area,” said Charles Babbitt, conservation chair of the Maricopa Audubon society. “With horses eating all the riparian tree saplings, these trees can’t grow into the mature cottonwoods that desert nesting bald eagles need. Yuma clapper rails also need the area to recover, but without the riparian vegetation, the situation is becoming increasingly hopeless.”

Simone Netherlands, president of the Salt River Wild Horse Management Group, is already working with the Forest Service to slow population growth by giving birth control to female horses via darts. She called the 600-horse estimate a “wild guess” and said the real number is around half of that.

“This horse herd is already being managed responsibly,” she said.

Netherlands pointed to the 8 million people who visit the Tonto every year, who she says do way more harm to the forest than horses through activities like hunting, mountain biking and horseback riding.

Conservationists maintain the horses threaten endangered animals and drive out other native wildlife that compete for food, like bighorn sheep and mule deer.

“Mule deer have already been run out of the area by the horses’ severe overgrazing,” said John Koleszar, past president of the Arizona Sportsmen for Wildlife Conservation. “Native quail have no nesting areas with the habitat so barren. The Forest Service here does dozens of management plans per year for cows. What could possibly be stopping them from doing a science-based plan for the Lower Salt?”

Netherlands says there’s no proof.

“Bighorn sheep are being seen again along the lower Salt River with babies, bald eagle populations are thriving and mule deer are benefiting greatly from the water troughs and emergency feed programs during drought,” she said.

Conservationists say the emergency feed programs are evidence that the land can’t support the high number of horses without significant human intervention.

The plaintiffs say both the 2017 intergovernmental agreement and the 2023 Salt River horse herd management plan violate the National Environmental Policy Act and Administrative Policy Act because they failed to take into account the horses’ impact on endangered species and the riparian area they live in. They want a federal judge to vacate both agreements and block the management plans pending a full NEPA review.

The center has gone after wild horses before. It sued the Forest Service in 2020 over unauthorized livestock in the White Mountains, where the estimated 600-horse herd roams the Black River watershed in the Apache-Sitgreaves National Forest.

The Forest Service didn't respond to a request for comment on the lawsuit by press time.