- Bird

How Do Cooper’s and Sharp-shinned Hawks Coexist in Backyards? FeederWatch Investigates

Closeup views of the heads and backs of two hawk species: brownish-gray Cooper's Hawk on the left and a bluish-gray Sharp-shinned Hawk on the right.
Cooper’s Hawk (left) by Bryan Calk, Sharp-shinned Hawk by Vickie Anderson through Macaulay Library.

From the Spring 2023 problem of Residing Chook journal. Subscribe now.

A brand new research utilizing Challenge FeederWatch knowledge confirmed why Cooper’s Hawks and Sharp-shinned Hawks can share the identical yard when looking at chook feeders.

The analysis, revealed in August 2022 within the Journal of Avian Biology, analyzed over 1,000 observations of accipiter predation from Challenge FeederWatch, a partnership between the Cornell Lab of Ornithology and Birds Canada, which collects knowledge from folks throughout the U.S. and Canada who depend birds at their feeders every winter. The research outcomes revealed which birds are on the menu for the 2 well-known feeder stalkers.

Sharp-shinned and Cooper’s Hawks are North America’s commonest accipiters—the group of hawks that makes a speciality of looking birds on the wing. Their ranges overlap broadly, and researchers needed to know if variations in prey preferences may be one cause that these two related species are generally capable of share the identical house.

Cooper’s Hawks are a lot bigger than sharpies (on common, they weigh twice as a lot and are 50% longer), however the analysis group discovered that small songbirds—particularly finches and sparrows—had been prime menu gadgets for each Cooper’s and sharpies. The general favourite: Darkish-eyed Juncos.

“Juncos are just like the popcorn of the avian world,” says lead writer Eliot Miller, a postdoctoral fellow on the Cornell Lab. He says juncos’ intense ground-feeding habits make them simple marks.

A composite image consisting of a photograph on the left and a graphic on the right. The photograph shows a hawk in flight, surrounded by seven smaller starlings. The graphic is a chart showing favored prey species for two species of hawk.
Numbers of Prey Taken by Species. Within the research, Challenge FeederWatch contributors recognized the prey species in additional than 1,800 Cooper’s Hawk and Sharp-shinned Hawk predator/prey interactions between 2015 and 2022. The graph reveals the highest 5 prey species noticed for every hawk, together with the variety of every prey species taken by the respective hawk. Each Cooper’s Hawks and Sharp-shinned Hawks steadily captured small songbirds similar to finches and sparrows, however Cooper’s Hawks additionally preyed on bigger birds similar to doves and pigeons. Picture reveals a Cooper’s Hawk flying amongst European Starlings, a standard prey merchandise. Picture by Jen Davis/Macaulay Library.

Whereas the petite Sharp-shinned Hawks closely favored these smaller species, the bulkier Cooper’s Hawks went for each the popcorn and the new canine. Together with taking their share of small birds, Cooper’s Hawks steadily focused medium-sized birds similar to doves, starlings, and blackbirds.

“The smaller birds are way more plentiful throughout totally different habitats,” says Miller, “so it is sensible that each hawk species would exploit that useful resource.”

Doves and starlings are sometimes concentrated in city areas, and Miller thinks that could possibly be one cause that Cooper’s Hawks have moved into cities in latest a long time.

The FeederWatch knowledge additionally confirmed that most of the most-preyed-upon chook species shared an inclination to forage and feed on the bottom. Quite the opposite, small songbirds similar to chickadees and nuthatches—which abscond to a protected perch after rapidly plucking seed from a feeder—turned hawk meals a lot much less steadily.

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