NATURE NOTES:
Rio Grande Joint Venture Fights to Save the Chihuahuan Desert’s Grassland Birds

By Andrew Stuart

They’re prairie seas, framed by desert-mountains – from the Marathon Basin to northern Mexico, the Chihuahuan Desert contains stretches of stunning grasslands. The grasslands support ranching, and iconic wildlife – from soaring raptors to sprinting pronghorn. 

They’re also home to a group of lesser-known creatures: birds known as “grassland specialists.” These small, secretive birds make continent-spanning journeys, and they’re facing a crisis.

In our region, the Rio Grande Joint Venture is leading the effort to preserve them.

Migratory Bird Joint Ventures started with a specific crisis: a rapid decline in ducks and other waterfowl. With support from hunting groups, U.S. Fish and Wildlife spearheaded regional partnerships to preserve wetland habitat. Government agencies, conservation groups and private landowners came together, and it worked: the partnerships helped halt the decline.

Aimee Roberson is coordinator for the Rio Grande Joint Venture.

“Because of that success, the Fish and Wildlife Service and their partners started to think, ‘Maybe this could work for other kinds of birds and habitats too,’” Roberson said. “In the last 10 to 15 years, that’s really been developing. Migratory birds are one of the species that really need these regional partnerships, because you have to think at a bigger scale to think about conserving them, and they’re not doing well.”

The Rio Grande Joint Venture works to preserve bird habitat in the Chihuahuan Desert and adjacent Tamaulipan Brushland, in both Texas and Mexico. In recent years, grassland birds have become a top priority. 

West Texas outdoors enthusiasts know that winter is raptor time. Eagles, harriers and hawks travel from as far away as Canada to winter here. But there’s an entire suite of birds that make that epic journey – and are likely to escape notice.

Weighing less than an ounce, rarely more than 6 inches in length, the “grassland specialists” include the Baird’s sparrow and McCown’s longspur, and two threatened species, the Sprague’s pipit and chestnut-collared longspur. They feed on grass seeds and insects. Their numbers are plummeting. 

“Grassland birds across the continent have been declining since 1970 at about 33 percent overall,” Roberson said. “But the grassland birds that winter in the Chihuahuan Desert have declined 70 percent, so at twice the rate as the whole suite of grassland birds. It’s an urgent crisis in conservation right now.”

They’re prey for raptors. They need grasses of sufficient height for cover. And they avoid shrubby areas, where predators like the loggerhead shrike, or “butcher bird,” can perch and scan the prairie for a meal. 

Some desert grasslands have been overgrazed, and mesquite and other shrubs have spread. And in Mexico, vast swaths are being converted into row agriculture. Habitat for grassland birds is vanishing.

The core of Roberson’s job is collaboration. Based in Alpine, she works with partners from Canada to Mexico, and with West Texas landowners, towards a shared vision of preserving the grasslands and their wildlife.

Texas Parks and Wildlife and federal agencies provide technical assistance and funding to landowners for rangeland improvements. Roberson helps connect landowners with these resources. The joint venture works with farmers in Mexico, to minimize the destruction of grasslands. 

At places like Mimms Ranch near Marfa, and at ranches in Chihuahua, landowners are experimenting with techniques of “holistic” or “regenerative” grazing. Livestock are managed in ways that simulate the action of wild herbivores, like bison.

Roberson said robust grasslands ultimately benefit not only birds, but livestock and wildlife – like pronghorn – that provide hunting revenue for landowners.

“Having healthy grasslands that can support livestock and wildlife is important to us, and all the private landowners we work with,” Roberson said. “The conservation community is trying to work more and more closely with the agricultural community, to really look at where those opportunities are and how they could be implemented. And I would say that’s true in both Mexico and the U.S.”

Lush after summer rains, golden in winter, the grasslands stand out in a desert land. The decline in grassland birds underscores their vulnerability.

“People have been aware of the issue for a while,” Roberson said, “but right now people are realizing it’s a crisis situation, similar to what we saw with waterfowl 30-plus years ago. There’s a recognition that if we don’t do something soon we could lose a lot of species and a lot of habitats.”