The Glamorous, Fabulous Ferruginous Hawk

(I'm no longer in California. I'll try to get my last few CA-themed blog posts written in the next couple of weeks before moving on to my next adventures!)

This is an article I wrote for the Golden Gate Parks Conservancy February 2014 e-ventures newsletter. It is currently published here:  http://www.parksconservancy.org/about/newsletters/park-e-ventures/2014/02-ggro.html

“Boy, I’d love to see a ferrug right now!”

This is one of the most often spoken statements by hawkwatchers at the Golden Gate Raptor Observatory, and understandably so. Large and majestic-looking, the Ferruginous Hawk (known as the “ferrug” in hawkwatcher short-hand) is arguably one of the most beautiful raptors we see at the GGRO. Adding to its desirability, Ferruginous Hawks are spotted from Hawk Hill no more than 20 times in a given year.

The Ferruginous Hawk is so named for the rusty-brown color infused on adults’ heads, backs, and upperwings. In the world of chemistry, rust is oxidized iron, known in the olden days as ferrous oxide. Add a couple letters and “ferrous” become “ferruginous.” The hawk’s scientific name also indicates its glamorous, physical appearance: Buteo regalis, which literally translates from Latin to mean “royal soaring-hawk.”

Often confused for an eagle because of its size, the Ferruginous Hawk is the largest North American buteo, the genus of hawks that includes Red-tailed Hawks, Red-shouldered Hawks, and Broad-winged Hawks. Identified by its characteristic long, tapered wings, large head, and robust chest, the Ferruginous Hawk is only one of three North American diurnal raptors to have legs feathered all the way to the toes (in addition to Rough-legged Hawks and Golden Eagles). In adults, these leg feathers are rusty-brown, forming a characteristic “V” shape that stands out when seen in flight. The chest of the Ferruginous Hawk is usually pale white, while the underwings of adults will have various amounts of rust-colored markings (brown in juveniles). 

Perhaps the most striking feature of these hawks, however, is the tail. In flight, the underside of the adult tail looks completely white, sometimes with light barring or some rust-color shining through towards the tip. Juveniles often show two to three gray bands towards the tip on the otherwise white tail.

During my first visit to Point Reyes National Seashore, I spent almost an hour watching a juvenile Ferruginous Hawk hunting over the grasslands. Using its long wings and tail to still in the air and moving its head back and forth, the hawk actively searched for jackrabbits and ground squirrels. Occasionally, it would stoop down and fly low over the ground before returning to its height to continue looking for prey. Cooperative hunting has also been reported in Ferruginous Hawks, where a male and female work together to catch prey.

For the motivated hawkwatchers, there are a few great places in the Bay Area to see Ferruginous Hawks overwintering. In Point Reyes, Pierce Point Road and the trail to Abbott’s Lagoon are surrounded by grassland habitat, ideal for seeing Ferruginous Hawks. Other areas worth checking out include Livermore Valley in Alameda County, Chileno Valley on the Marin-Sonoma County borderlands, and the southern extension of Chalome Valley between highway 41 and Bitterwater Road. The best time of year to look for Ferruginous Hawks in these areas is between December and February.

Seeing a Ferruginous Hawk from Hawk Hill is quite a treat. Although a sighting is rare, it is clear why hawkwatchers consistently consider this elusive bird to be truly glamorous!

(Thanks to Allen Fish, Bob Power, and Tim Behr for tips on where to find wintering Ferruginous Hawks!)