The Rusty Squirrel-Hawk AKA Ferruginous Hawk
The Ferruginous Hawk (Buteo regalis) is truly a regal bird. Sporting a 56 inch wingspan, it is the largest of the Buteos. They inhabit the grasslands, shrub steppes, and deserts of western and central North America. Click on photos for full sized images.
Ferruginous Hawks were known as Rusty Squirrel-Hawks back in the 1800’s and they exist in both a light and dark morph. I took a ride up to the Fall River Valley back in October and spotted both morphs in the large grasslands where we also usually see Rough-legged Hawks and Prairie Falcons. This is the light morph.
They are often seen on the ground since their prey consists mainly of rabbit, prairie dog and, you guessed it, ground squirrel.
And this is what the dark morph looks like.
Note the long yellow gape, a characteristic field mark of this species.
For the past five years I have been fortunate to have a Ferruginous Hawk wintering near a farm in a grassland area below the foothills where I live.
Ferruginous Hawks were petitioned for listing under the federal Endangered Species Act in 1991 but rejected; currently they are listed as a Category 2 Species by the U.S. Fish and Wildlife Service and as a Sensitive Species by the Bureau of Land Management1. They are listed as vulnerable in Canada.
A study conducted by Richard Olendorff, working for the U.S. Bureau of Land Management, suggested that management measures aimed at maintaining current population numbers should include enhancing nest substrates, maintaining prey populations, and mitigating development impacts from mining, pipeline construction, and urbanization2.
Obviously more research needs to be done on this magnificent raptor. The latest study I found was a migration study which included Canada, the United States and Mexico done by the Rocky Mountain Bird Observatory.
I hope to see my winter visitor for many years to come as these birds can live 20 years in the wild! In the meantime, I found a cool video of the Ferruginous Hawk in slow motion. It is an education bird from the Arizona-Sonora Desert Museum’s Raptor Free Flight program. Enjoy!
References: 1Birds of North America Online, 2Olendorff, R. R. 1993. Status, biology, and management of Ferruginous Hawks: a review. Raptor Res. and Tech. Asst. Cen., Spec. Rep. U.S. Dep. Interior, Bur. Land Manage. Boise, ID.