Breeding Bird Atlas 2 Results

See all of the BBA2 data to date on the USGS BBA Explorer.

Preliminary Results:
Cooper's Hawk: A Major Population Change

Latin Name: Accipiter cooperii
Breeding Habitat: Mixed, mature forests
Massachusetts Status: Increasing

Cooper's Hawks are fairly widespread breeders in Massachusetts and throughout much of the United States. They prey mainly on birds, which is probably why most novice birders' first encounter with a Cooper’s Hawk is watching them come into a bird feeder for a meal. They are powerful, yet agile on the wing. These traits make them the classic forest hawk.

Cooper's Hawk depend on forests for breeding, and the rapid expansion of this species during the late 1900s closely parallels the reforestation of Massachusetts during the same time period.

They nest in mixed woodlands or mature suburban landscapes, often placing their nests fairly high up in pine or oak trees. It is also interesting to note that while these birds can be very much in evidence during the nonbreeding season, they become very secretive while on the nest.

Many Cooper's Hawks from eastern North America migrate during the fall to central or southern United States, although some remain in Massachusetts during the winter.

Breeding Population Changes Between BBA1 and BBA2

Cooper’s Hawks, like most other hawks, have had a history of fluctuating populations and ranges. Clearing of forests, which are required for Cooper’s hawk nest sites, during the 18th and 19th centuries, and direct persecution by gunners, caused wide-scale declines in Cooper’s Hawks and many other forest-nesting raptors.

The protection from shooting afforded by the Migratory Bird Treaty Act of 1918, along with wide-scale recovery of forests during the latter half of the 20th century, combined to allow Cooper’s hawks to recolonize, and perhaps expand beyond, their historic range.

BBA1 results showed Cooper’s Hawk was a rare breeding bird in Massachusetts. In what may be one of the most dramatic range recovery stories of the late 1900s, this species showed a spectacular increase to become one of our more widespread breeding raptors.

The scale Cooper’s Hawk recovery is matched by few other species – and has occurred in all regions of the state. During BBA1, Cooper’s Hawks were found in 1% of the blocks surveyed, and by the end of the 2008 surveys they’d been found in 44% of the blocks.