The prairies have faded from green to gold, as dry, clear days settle in. Birdsong has stilled, and the bustle of bugs, rodents and reptiles has ended. Winter in West Texas can seem like a time of quietude, when life is on hiatus.
Yet it’s precisely now that one ecosystem here is beginning to thrum with vibrant life. Chihuahuan Desert grasslands are the main winter home for birds known as grassland specialists – chestnut-collared and thick-billed longspurs, lark buntings and horned larks, Sprague’s pipits and diverse sparrows. These birds are deeply imperiled, and supporting them is a top priority for West Texas conservationists.
Dr. Maureen Frank is a bird conservation scientist at Alpine’s Borderlands Research Institute.
“Ninety percent of migratory grassland-obligate birds in the North American Great Plains spend the winters here in the Chihuahuan Desert,” she said. “So that's a huge number. And the winter is really important.”
Grassland birds, Frank said, are a long-term focus for the BRI.
And for good reason. These birds have declined by half since 1970 – that’s a loss of 720 million birds. And some species – including grasshopper and Baird’s sparrows – have declined by almost 70 percent.
It’s mostly due to vanishing habitat. North America has lost more than 80 percent of its grasslands since European settlement – through farming and urbanization, invasive species and grazing impacts.
Much of the effort to restore the birds has centered on their breeding grounds in the Dakotas and Montana, Alberta and Saskatchewan. But Frank said what happens in West Texas and northern Mexico is just as important.
“There’s kind of been this focus on what's happening on the breeding grounds,” Frank said, “because, well, if we need more birds, then we should probably focus on the time of year when more birds are made. But if they don't survive the winter, you're still not getting those back into the population.”
The BRI began monitoring grassland birds at the Dixon Water Foundation’s Mimms Ranch, near Marfa, in 2017. They’ve used tracking devices, and they conduct annual foot surveys.
Now, they’ve installed recording devices at livestock tanks. No human could listen to all the hours of resulting audio, Frank said. But with AI software, the recorded bird calls can be identified, and the technology is deepening our understanding of wintering bird populations.
Those populations were down dramatically last year, amidst historic drought. Upcoming surveys will reveal whether their numbers have rebounded.
But BRI scientists are also taking steps to support the birds. On the Marfa and Marathon grasslands, herbicide has been applied to knock back brushy plants – mesquite, in particular – and heavy equipment has been used to remove the dead brush.
Brush removal allows grasses to return – which means food and shelter for the birds. But reducing brush also reduces predation. Mesquites are perfect perches for American kestrels – or “sparrow hawks” – and loggerhead shrikes, which prey on grassland birds.
Frank said the grassland specialists are already returning to places where brush has been removed.
“Those are starting to move even without much rain – they're starting to move back to that grassland community,” she said. “So that's really encouraging, in that, hopefully, as we get more rain, we trend back towards a grasslands community.”
These grassland birds are little – weighing an ounce or less, with 6- to 12-inch wingspans – and are often the color of the prairie itself. Many journey more than a thousand miles to winter here. As efforts to restore West Texas grasslands continue, the fate of these vivid creatures – emblems of the desert plains – hangs in the balance.
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