Salt River Horses Destroying Endangered Bird Habitat, Wildlife Experts Say

The 100 or so free-roaming horses that the Tonto National Forest Service marked for roundup earlier this month aren’t the only animals in danger of getting ousted from their homes along the banks of Arizona’s Salt River.

But it’s not the Forest Service that’s threatening these animals. It’s the horses.

Wildlife experts say the horses, which are not native to North America, have been chomping on cottonwood seedlings, preventing the trees from growing to maturity. Birds, such as the western yellow-billed cuckoo and the southern bald eagle, rely on the cottonwoods for nesting and breeding.

The U.S. Fish and Wildlife Service listed the yellow-billed cuckoo, a white-bellied bird known for it’s distinctive “kwolp” call, under the Endangered Species Act in November.

There are only about 350 to 500 pairs of cuckoos nationwide, according to the American Bird Conservancy. In Arizona, considered one of the last strongholds for the birds, the population has dropped between 70 percent and 80 percent since the 1980s.

The cuckoos’ decline coincides with the demise of about 90 percent of their riverside habitat, says Russell Haughey, a retired wildlife manager for the Arizona Game and Fish Department who now teaches biology at Scottsdale Community College. The cottonwoods are struggling for a number of reasons, including development and irregular flooding patterns, which, Haughey argues, makes reining in the horses all the more critical.

While no one has investigated the impact of the horses on the Salt River cottonwoods directly, a number of studies have documented the negative effects of livestock grazing in nearby areas. Along Sycamore Creek, for example, the USFS Rocky Mountain Experimental Station found that 100 years of continual cattle grazing virtually halted the growth of new sycamores.

Because of their ecological impact, cattle generally are banned from riverside grazing, Haughey says. If their numbers get out of control, they are removed and sold.

“I believe the horses have continued what the cattle before them started,” Haughey says. The horses, however, “are not managed at all” and, as a result, are a threat to the yellow-billed cuckoo and many other wildlife species that make their homes on the riverbanks.

The southern bald eagle, which builds nests in mature cottonwood trees along the Salt River, still is struggling to recover after several tenuous decades on the endangered species list, says Tice Supplee, interim executive director for Audubon Arizona. There are about 60 pairs in the state, up from just a handful in the 1970s. 

“I love horses, but I’m also really concerned about the eagles,” she says. “If there are no new trees growing, we won’t get new eagle nests.”

Like the Forest Service, Supplee believes the horses are descended from ranch horses that strayed from two nearby Native American reservations. She believes the horses should be moved to pastures, rotating each season to prevent over grazing.

“As an owner of horses, I’m at a loss to understand this idea of letting these poor animals roam around. That’s like throwing your dog out on the street,” she says. “They would be better off cared for.”

Simone Netherlands, head of the Salt River Wild Horse Management Group, the nonprofit that has led the resistance against the Forest Service, argues, however, that the horses are a boon to the river ecosystem. She maintains that the horses have been running free along the Salt River since Spanish missionaries first brought horses to the area in the 17th century.

“The Salt River wild horses love to eat the eel grass that grows in the river,” she says. “Without the horses, the river would become clogged with the eel grass, such as it is in many areas already. The eel grass overgrows and stops the flow of the river. It also catches all the garbage in the river.”

The Salt River Wild Horse Management Group and the Colorado-based advocacy group Friends of Animals have filed suit against the Forest Service for failing to conduct an environmental-impact study before publishing an impound notice at the beginning of August, which they claim is a violation of the National Environmental Policy Act of 1969.

In response to the lawsuits and furious public protest, the Forest Service announced plans last week to postpone “any action regarding the horses” for at least 120 days while officials work with the Salt River Wild Horse Management Group and other interested parties to “find a collaborative solution.”

Netherlands says the Salt River Wild Horse Management Group hopes to work out a compromise that protects the Salt River environment and “all wildlife.”

Haughey and Supplee hope that includes the yellow-billed cuckoo and the bald eagle.