This is Playa Country — a weekly look at the wildlife, wetlands and prairies of the western Great Plains, and the people who manage them — brought to you by Playa Lakes Joint Venture, an organization dedicated to conserving birds and bird habitat.
This year, 2016, marks the centennial of the first Migratory Bird Treaty, which the United States signed with Great Britain on behalf of Canada. That treaty and the three that followed — with Japan, Russia and Mexico — form the cornerstones of our efforts to conserve migratory birds, like the Lark Bunting.
He’s a common sparrow of the Great Plains, one of many grassland birds — birds that rely on grasslands for all or most of their life-cycles.
“In order to define a grassland bird, we probably need to define a grassland. An open, expanse of land dominated by native grasses and forbes, with various interfaces with shrublands and riparian corridors.”
Arvind Panjabi — he’s International Program Director for Bird Conservancy of the Rockies. Grassland birds share similarities. Some winter in south New Mexico and south Texas, but most fly into the northern third of Mexico. They winter in the Chihuahuan Desert that straddles the U.S.-Mexico border in the northern part of the Mexican Plateau. These birds commute north to breed — some as far as the prairies of central Canada, but many brood their young in the shortgrass prairies of the High Plains. This Lark Bunting, this is a bird of mystery. Once very common on the plains, this bird has suffered population decline for decades.
“It is in dramatic decline.” Susan Skagen is a researcher for the U.S. Geological Survey. “The Breeding Bird Survey, a citizen science survey… they’re showing that they’re declining by from three to four percent a year.”
The bird’s population has been dropping every year of the past 50, and scientists are unable to explain it, but this decline seems to be related to the bird’s predators.
“Probably 92 percent of the nest failures are due to predation. So I’m thinking that the predator communities have been altered in some way, or perhaps the other prey these predators might go after have been altered in some way.”
Lark Bunting males have developed a unique way of attracting a mate. They zoom up in the sky and sing. Scientists call it “song flight.”
“They start right after sunrise, and they will do as many as 20 to 30 song flights in an hour. They’re quite loud. They’re quite vocal. Their songs are a variety of whistles and trills, sort of sweet in tone, but also harsh in tone. Once you hear them, you can’t miss them. You’ll hear them all over the place. And they actually continue all day doing these song flights.”
As common as this bird once was, it’s population has declined nearly 90 percent since the mid-’60s. Arvind Panjabi speculates this bird’s problem might have to do with its wintering habitat in Mexico.
“Where they spend the rest of the year outside of Colorado. Lark Bunting, like Cassin’s Sparrow and most of the other grassland birds from Colorado and the western Great Plains, all funnel down into the Chihuahuan desert to spend the winter months, which can be up to eight months of the year. They start showing up in Mexico as early as the end of July. As soon as they are done nesting up here, they head south, back to their homeland, and things are changing down there pretty fast.”
That desert, he says, is being turned into cropland. Panjabi says one way landowners and grassland managers can help the bird is simply to keep ranch land in ranching, because having an economic use of the land that’s compatible with these birds is essential. Just by maintaining your ranchland, he says, you’re helping one species or another.
Playa Country, a weekly show about the wildlife, people and landscapes of the western Great Plains is made possible by the Playa Lakes and Rainwater Basin Joint Ventures. Our thanks to Cornell Lab of Ornithology’s Macaulay Library, in Ithaca New York, for the Lark Bunting bird song.
Original broadcast: March 2016