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 Ferruginous Hawk.
Other than the eagle, with a 53-inch wingspan, the Ferruginous Hawk is the largest bird-of-prey found on the plains. It’s habitat in summer and winter includes grasslands, deserts and other open areas featuring isolated shrubs and trees, and where less than half of the ground is under cultivation. Jim Watson is a research scientist at Concrete, Washington, who’s studied this bird for years. He grew up in Colorado, and spent a lot of time as an early teen out on the Pawnee Grasslands.
“I remember coming up over a hill and right in front of me there was this big white flash, and I watch this beautiful hawk fly away. Of course, it was a Ferruginous Hawk. I think, at that point on, I became pretty much enamored with the species, not just because of their beauty and their size, but their association with prairie habitat and native ecosystems.”
Many Ferruginous Hawks migrate in Spring to the far northern latitudes to breed and brood, and return to the southwest states and Mexico to winter. For others, their idea of “north” isn’t so ambitious — they might fly north only as far as Nebraska or Kansas to hatch chicks. And some of them really don’t migrate.
“Birds from that area are really the least migratory owing largely to the relatively mild climate compared to some other places these birds nest in. So they don’t need to migrate.”
Jim Watson studies hawk migration for Washington Department of Fish and Wildlife. He says some of these birds-of-prey are happy to live more or less all year on the southern plains, because their favorite food is there.
“That is the prairie dog population. Primarily prairie dogs and pocket gophers are very important to those birds; throughout much of the winter they are available in one place or another, depending on snow conditions.”
In winter, those prairie dog communities of the southern plains attract Ferruginous Hawks from across the country, but they also prey on other things. They have huge mouths, and can swallow most prairie rodents whole.
“They’re probably the rancher’s best friend as far as what they feed on, because they feed on small mammals — ground squirrels, prairie dogs, pocket gophers, rabbits (jackrabbits and cottontails).”
But the meal of choice for this hawk, is the prairie dog. And that’s a problem, because prairie dog populations are in decline.
“The loss of prairie dogs has been important for both wintering and breeding Ferruginous Hawk down in your area. There are some concerns associated with feeding on prairie dogs, not the least of which is the more recent use of some of the poisons like Rozol that are becoming fairly prolific and have a very high potency and a potential for secondary poisoning, particularly of the wintering birds.”
That poison, Rozol, is licensed to kill prairie dogs. Raptors, coyotes, foxes and raccoons eat the poisoned dogs, and in that second-hand way ingest a lethal poison. That’s why regulations require that Rozol applicators properly dispose of prairie dog carcasses. This hawk endures another peril. Some people have the idea that Ferruginous, and Swainson’s Hawks, feed on game birds — pheasant, quail or grouse. It just isn’t so.
“Of course, the irony there and the message I try to broadcast is these birds don’t hunt upland birds. These birds are mammal feeders. That’s what they do for a living.”
Thanks to Cornell Lab of Ornithology’s Macaulay Library in Ithaca New York, for the featured bird song. Playa Country, a weekly show about the wildlife, people and landscapes of the western Great Plains. Made possible by the Playa Lakes and Rainwater Basin Joint Ventures.
Original broadcast: March 2016