For a widespread and common bird like Red-tailed Hawk, you might think we know all we possibly can about its migratory behaviors. But just a year ago, researchers confirmed that juveniles in certain southern populations fly far to the north before returning south again, and now a team of biologists from Wyoming has added more details.
From 1999 to 2002, Derek Craighead and his colleagues tracked 16 adult Red-tails from nesting areas in Wyoming to their wintering regions and back again to the Cowboy State. All of the birds wintered in Mexico. Most traveled to western Mexico, two went to eastern regions, and one flew to the southernmost state of Chiapas — a round-trip of about 5,100 miles.
On average, the birds left their breeding grounds in mid-October and arrived at their wintering territories in early November. They started their return flights in mid-March and arrived at their breeding sites in early April.
The researchers report in the Wilson Journal of Ornithology that the hawks performed leapfrog migrations: They flew well beyond the year-round territories of Red-tails in the southwestern United States, probably to avoid competing for resources with the resident birds. The behavior has previously been reported in Red-tails, American Kestrel, and other raptors.
Craighead also found that the birds migrated not in relatively straight back-and-forth lines but in loops. In spring, they flew farther west than they did in fall, most likely to take advantage of better prey habitats. The discovery is the first direct evidence of loop migration in Red-tailed Hawk.
Read the abstract
Derek Craighead, Ross H. Crandall, Roger N. Smith, and Steven L. Cain, 2016, Migration of Red-tailed Hawks (Buteo jamaicensis) from northwest Wyoming. The Wilson Journal of Ornithology: March 2016, Vol. 128, No. 1, pp. 150-158. Abstract.
A version of this article appeared in the August 2016 issue of BirdWatching magazine. Subscribe.