Aerial Acrobat: Cooper’s Hawk
Aerial Acrobat: Cooper’s Hawk
In California we have three accipiters (class of hawks, with short broad wings adapted for flying through the woods); one, the Cooper’s Hawk, is often described as ‘crow’ sized. Speaking of crows, keep your eyes peeled as crows often mob Cooper’s Hawks and this behavior can reveal the location of the hawk and provide a good opportunity for size comparison.
The Cooper’s Hawk is the most common of the two accipiters found in Alameda and it’s likely the accipiter that just flew by! It is very exciting to see these aerial acrobats in action. They will even run along a tree branch to get into better launch position for their next attack. Think of them as ambush predators.
Cooper’s Hawks do well in urban settings as long as there is sufficient wooded habitat. They are not a typical species of open country but can be found nearby if the perimeter of the open space offers some bushy cover. For instance, I often find them at Merced National Wildlife Refuge in trees or heavy vegetation but not out in the open, the way one sees Northern Harriers or Red-tailed Hawks patrolling wet¬lands and grasslands.
Crab Cove in Alameda is a great spot to see Cooper’s Hawks, as are the tree-lined areas of Corica Park golf course. Recently, at Chochenyo Park four juveniles were seen bathing in a puddle of water. Later, they were observed in the backyards of the surrounding houses using both trees and human structures as roosting and eating sites. During four weeks of observing the Chochenyo family I saw them capture and eat only birds. Several times the Cooper’s juveniles attempted to take ground squirrels but they were not successful. They eat mostly birds, but are known to prey on mammals, reptiles, and insects.
Sibley Field Guide to Birds describes the bird as 16.5 inches long with a wingspan of 31 inches, weighing in at just under a pound. They have a brownish or blue-grey back and reddish vertical bars on the breast, with a white chin and alternating bands of lighter and darker brown or grey on the tail. The female is larger than the male but the male is usually a little brighter in color. Cooper’s are found throughout North America and are considered monogamous. The female normally lays a clutch of two to five eggs in late April to May and the young fledge in four to five weeks. They remain in the area of the nest and interact as a family group for several more weeks after fledging. The family of four juveniles I observed at Chochenyo Park continued to interact with one another frequently after leaving the nest. The adults were largely absent.
The Cooper’s Hawk was named for William Cooper, a New York scientist, almost 200 years ago in 1828.
These dramatic and entertaining hawks, like all raptors, are susceptible to chemicals and pesticides. And since they literally live amongst us, it imperative that we use environmental best practices and strive to create and sustain suitable neighborhoods that are favorable to people, birds, mammals, and insects.
Rick Lewis is a Golden Gate Audubon member and contributing photographer to several Bay Area environmental organizations.