Yesterday, I gazed out the window of my home office during a meeting, watching California quail and house sparrows forage beneath native sumac. Suddenly, the bush seemed to explode, with birds flushing in every direction.
A second later, a Cooper’s hawk deftly landed underneath the shrubbery. It began hopping around attempting to snag one of the remaining quail that hunkered down instead of flushing. But the hawk was just a little too late.
Over the years, I’ve noted more frequent sightings of both Cooper’s and sharp-shinned hawks around the neighborhood. You’ve probably noticed the same thing. Across the United States, these two hawk species – both similar looking and in the genus Accipiter – have increasingly colonized urban areas.
A new paper in the Proceedings of the Royal Society B sought to “identify factors that determine the occupancy, colonization and persistence of Accipiter hawks in a major metropolitan area.” In the course of their study, the researchers from the University of Wisconsin-Madison and Cornell Lab of Ornithology found that in the 1990s Accipiter hawks occupied 26 percent of sites around Chicago. After two decades, they occupied close to 67 percent of sites.
It’s a trend reported (often via citizen science) around the country. And a big part of it is the bird feeder in your backyard.
The Return of Raptors
By the mid-20th century, many raptor species, including Cooper’s and sharp-shinned hawks, had declined precipitously. Direct persecution and pesticides had taken a heavy toll. Decades of protection have caused populations to rebound, leading raptors including accipiters to reclaim habitat.
But as the birds spread, they found a new world: one of growing cities. One might initially conclude that predators would not find this new world to their liking, as it was covered in concrete and buildings instead of forests. And that’s certainly true for many wildlife species.
But, as the researchers note in their recent paper, cities present a mix of habitats, including backyards, parks and golf courses with plenty of space. These “novel ecosystems” provide opportunity for cover and also, often, for ample food supplies.
The researchers documented the spread of the two hawk species in Chicago via observation through remote sensing data and Project FeederWatch, a citizen science initiative that has conservationists record sightings throughout the winter.
Initially, the hawks colonized areas outside the city. But they increasingly spread to more and more urbanized areas. The researchers documented usage of areas defined by what they call impervious features: roads, buildings, sidewalks. The more impervious the area, generally, the less “green” habitat.
Initially, hawks avoided these highly developed zones. But eventually, as long as there was sufficient prey, they colonized even the downtown. Over the past two years, hawks went from the city fringes to occupying much of the metropolitan area.
The researchers hypothesized that reforestation would play a role in hawk recolonization. But it didn’t. In fact, wintering hawks preferred areas with fewer trees, perhaps to better hunt prey.
The Hawk at the Feeder
Bird feeding is a hugely popular urban pastime. More than 40 percent of U.S. households feed their backyard birds.
That creates an abundance of birds, concentrated in specific, predictable areas. A predator’s bonanza.
The researchers found that the predator’s persistence in urban areas was most influenced by abundant prey. Based on citizen science and other research across the country, hawks have taken advantage of the bounty of bird feeders across the country.
Cities are rapidly changing. The novel ecosystems they create are also highly dynamic and, often, poorly understood. Songbirds, like northern cardinals, may even expand their range due to feeders. Then predators recolonize, shifting species behavior and abundance.
The researchers cite studies in England that show the recolonization of Eurasian sparrowhawks in cities caused a dramatic decline in house sparrows as well as other species commonly found at bird feeders. The sparrows had exploded in population due to the free food sources and lack of predators. When the predators returned, it caused an immediate shift in the urban ecosystem. It’s not so different, really, than what happened when wolves were reintroduced to Yellowstone and found a park with an over-population of elk.
The researchers note that similar shifts in prey abundance might be expected in Chicago and other cities. Some studies have found that urban hawks are feeding heavily on European starlings, house sparrows and pigeons – all non-native species – so they could actually reduce competition for native songbirds.
Do bird feeders change migration patterns? At least one study found that sharp-shinned hawks on the East Coast were less likely to migrate due to the abundance of bird feeders.
Research into Urban Ecosystems is Vital for the Future of Conservation
Clearly, research into urban ecosystems is vital for the future of conservation. Understanding how species interact, and how species use new habitats, can help better design parks and refuges. Perhaps endangered animals that many consider incompatible with cities actually could recolonize urban areas if given a chance. After all, 50 years ago no one considered the Cooper’s hawk to be an urban bird.
And let’s not forget a key factor in helping scientists understand urban wildlife: you. The observations you make at your bird feeder, at the city park and along a greenbelt trail help researchers understand novel ecosystems and their wild inhabitants. While your observations may seem anecdotal, when combined with millions of other observers, they add up to a significant data set.
So, yes, you really are seeing more hawks at your bird feeder. Enjoy the show this winter: the restoration of the predator-prey dynamic to the urban wild.
Experience at bird feeder just east of Hamilton, OH, 45011. A pair of brownish hawks nested in Silver Maple trees about 60 feet off the ground and to feed on the native song birds at my bird feeder filled with sunflower seeds. To stop the predation of the feeding song birds; a screen of wire trellises was place about 3 feet from the feeded. The song birds were no longer preyed upon while at my feeder. The birds did have to fly more that 60 feet from cover to the feeder. Several sunflower seeds grew to maturity along these trellises, helping to mask the severity of the bare wire trellises.
I have continued the wire trellis screening thru winter.
All this appears to be true. I have had both Cooper’s Hawks and Sharp Shinned Hawks in my urban yard. We have only lived here for just over a year. Having seen both birds on our farm, I was surprised to see them visit pour in town home. This occurred after we began feeding the local birds. We used to have 20+ sparrows, several woodpeckers, many dove, wrens, cardinal, bluejays and starlings.
All that changed after the Hawks came. Lots of feathers from “kills” and the NO birds.
It is now rare to see more than a few Juncos and no other species. They to eat as well but spread it around please.
Interesting article; it certainly fits with what I’ve seen over the past two decades of birding.
I have been seeing a hawk/hawks in my small town backyard. Now I know why. Seeing them is cool. I hate that some smaller birds might be killed but hawks have to eat too. And they don’t have the alternative options that humans do.
We have had a pair of Sharp-shinned hawks “feeding” at our bird feeders for several years now. They took many birds feeding at our hanging suet feeders. We do have fewer songbirds now.
Recently I started placing seed under a wrought iron table by the pool and we seem to have many more songbirds eating in the relative protection underneath.
Yes! I live in Akron, Ohio, about one hour south of Cleveland . This is the fist time I’ve seen these hawks near my birdfeeders in the winter. I haven’t seen them take any birds, but they do capture the squirrels trying to get the bird food. We live on a lake so I also put cracked corn out for the ducks in the winter. This year I haven’t seen any ducks get captured, but about 4 years ago we had a pair of bald eagles nearby that ate a number of ducks out on the ice, near a tiny island in the center of the lake. Yesterday, for the first time since then, I spotted a bald eagle sitting in one of our trees watching the ducks in the water, which is about 3/4 frozen. He soon flew away without a meal. I LOVE the nature show in my backyard!
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I lived in Portland, Oregon for almost 10 years, and next to my house was an one-acre open field, ringed by numerous large trees, that eventually became a CSA farm. There were Cooper’s and Sharp-shinned Hawks working the area the whole time I lived there. Once I saw one take out a robin in mid-air, pinning it to the chain link fence with wings flapping wildly, till dead. And after I and all my neighbors started keeping backyard chickens, there developed a rat issue which prompted most of us to get rid of the chickens, but was a boon for the hawks. Once while working in the garden I watched one snag a big fat rat, carrying it squirming and squealing up to an old growth Doug fir to enjoy for lunch!
This article makes a lot of sense to me. I live in a quiet wooded neighborhood in Metro Atlanta. I was feeder watching in my sun room recently and observed a Coopers hawk chasing a terrified sparrow right at me into my plate glass window. It was so fast I ducked! Fortunately the sparrow flew up and avoided the window at the very last moment and the hawk banged his head and flew away empty handed. However I found a lot of feathers on the deck this morning so he may have been successful the next time.
I had a sharpie settle in for meals in my Brooklyn, NY garden earlier this year. My neighborhood is all brownstones and low rise apartment buildings. I have a feeder that attracts mainly sparrows and mourning doves. I saw this hawk dive a few times while I was indoors but I figured it would keep its distance once I was outside working at close quarters. Hah! While my back was turned that hawk swooped in to kill not ten feet away from me.
Excellent article! I live in the Albuquerque, NM suburb of Rio Rancho, and a Cooper’s Hawk occasionally shows up in my backyard.
We have a resident pair of Coopers Hawks who have been successfully fledging young next to our backyard. They nest in a Eucalyptus tree but use a power pole as the “hand off”spot when the hunting parent returns with dinner. The hunter has a distinct vocalization to call the sitting parent. Very cool to see the handoff at such close range. I can’t wait for their breeding season to get here again.
FYI We are near downtown San Diego.
There are interesting videos on you tube depicting accipiter’s ability to navigate thru suburban landscapes to catch birds. I have had a sharpie in the yard for years, and hang my feeder in dense 10 ‘ high shrubs. Not perfect, but helpful. The small birds know this hawk and sound the alarm whenever he’s around.
My yard has a 50′ by 50’ lawn framed by shrubs and trees in an area that ranges from suburban to semi rural.
We have seen and heard Barred Owls in the neighborhood for the past twenty years, but I don’t remember seeing a Coopers Hawk until about five years ago when I found one sitting on the roof of a post feeder in our front yard. I have not seen a hawk catch a bird, but have occasionally found a pile of the leftover feathers. Most of the feathers found were those of a Dove, but every once in a while I find a Cardinal. Last summer while walking our dogs down the street, from a distance I saw what I thought looked like a Red Tailed hawk carry a squirrel from one large oak tree across the street to another, but the hawk dropped the squirrel just short of the second tree. Although the hawk did not stop but continued flying south to a third tree, a nearby neighbor saw a hawk later return to retrieve the squirrel.
Yes, we have seen Cooper’s hawks at our feeders, mutilple times over the past years. We live in Boulder Co.
Last year I found a hawk sitting on my fire escape. I took her picture and since then she comes around periodically. I suppose she has ample prey since we also have lots of song birds and field mice. I was astonished but ever so happy. I think it was a female since it seemed larger than the Male which has also appeared this past summer.