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.
I have been concerned about the resurgence of these hawks. Although, I do not regret the loss of our burgeoning chipmonk population, isnt there a risk of imbalance? I feel I am seeing way too many hawks. They are unafraid of me, and often watch me in the garden.
Hi Sandra,
Thanks for your comment and question. Predators are a natural part of a healthy ecosystem. They are focusing on the most abundant prey, so there is not evidence they are negatively impacting native songbird populations. In my neighborhood, for instance, the influx of hawks is feeding on California quail, house sparrows and fox squirrels — and these are all non-native species.
Just last week (mid January) I looked out my window to the world and across the street on a fence post was a beautiful sharp shinned hawk! The sight was mesmerizing… This is in the town of Vancouver WA USA… A few days later I believe it was at the top of a tall Hawthorn tree. Not sure if it was the same bird as that was far away and my binoculars were in my car ~ drat!
Kansas City provides an open woodland environment and even near downtown, there are fingers of forest that go into housing areas. Though, whole waiting one day at an intrsection and some construction, I watched a Cooper’s hawk flush pigeons off a building at 31st and Main, then snatch one up to eat. It settled on a decorative top building edge to pick it.
I moved a bit farther south, and the Barred Owlsand Coopers Hawks keep the birds and squirrels on their toes.
I enjoyed your article, we have 4 bird feeders as well as 2 bird baths. The Cooper’s hawks enjoy sitting in the trees or on the fence behind the shrubs looking for their prey. They do succeed but a lot of times they don’t. There is a squirrel that actually chases the hawks away when they are both around. I have noticed that the hawks are more prevalent now than a few years ago.
I gave a pair of Cooper Hawks that hang around my feeders. They usually go after turtle doves. They only come about once or maybe twice a week. They sit on my gutter or trees close by my feeders. They usually leave the small birds alone and go after the doves.
I enjoy reading about nature in so many ways . The joy of seeing birds of prey & many other birds & animals of nature is beautiful!
A Cooper’s Hawk resides in our Wilmette neighborhood and is often seen terrorizing songbirds. Most interesting, though, was when my spouse saw it glide across our back yard and perch atop our fence for a better view of the skunk ambling along on the other side. The hawk hopped along above the skunk for a minute or two before thinking better of it, and then flew silently away.
We really appreciate informative articles, especially as the dynamics keep changing in our world, so we can keep up and change as we should. Thank you.
In the past 10 years, Cooper’s hawks have become increasingly visible at my home in the city of Milwaukee. It seems directly related to the presence of bird feeders. While there are tons of starlings year round, it is not their prey of choice. They really depradadate the mourning doves. It was not unusual to count 30 or more doves. Today I am lucky to see 5-10. I often find the remainders of these doves under my own feeders.. The crows in the area are always harassing the Coopers in spite of the crows steep losses from West Nile Fever. It will be interesting to see how this plays out in the future
We live in a suburban area in Albany, New York. We feed the birds and squirrels in our yard. I noticed a Cooper Hawk in a tree by our house. To my disbelief he swooped down and got a little Sparrow. I told my cousin if I had a gun I would shoot it. She told me it is survival of the fittest. He came back a few more times that winter and grabbed up the small birds. I was so frustrated! I can not stand to see any hawks near our house. I was always under the impression that hawks lived in forests. We have a fairly large park at the end of our street with a lot of tree cover. I think that is where they come from. I am one of those people that feel guilty for feeding the birds and having them come to my feeders to eat and get eaten. I know all animals have to eat but I have been researching to see if there is anything I can put out for the hawks.
I have 4 small bird feeders outside of my dining room window so imagine my surprise when I looked out several days ago and saw a Cooper’s hawk walking around the ground under the feeders. All of the birds had flown away and only a lone squirrel was hunkered down in the one flat open feeder. The bird then perched on one of the landscape light fixtures before flying away. My granddaughter had seen him several days earlier. He was small and an immature bird. Wish I could include the photos I took.
We have a virtual bird sanctuary in our small backyard with varied feeders, evergreen trees and shrubbery, and a pond with waterfall. A family of several generations of crows frequents a feeder tray (with dog kibble), the pond, and the garage roof (where they get occasional bread or cheese.) One at a time they hang in the cedar outside my son’s window and meet him outside when they want a cheese or bread treat.
We also have a sharpie and a Cooper’s which hang around, usually on the fence near the feeders. The crows don’t like them. They call their friends and with incredible cawing the dozens chase the hawks from the neighborhood. That’s how they earn their feeder tray and occasional treats. The mob has also been photographed chasing an eagle who landed street side with the possum he was carrying.
Interestingly the crows disappear when our mini Aussie goes in the yard. The songbirds are not bothered by him.
Thank you for this article! I put out food every morning for the local birds & squirrels. Have done so for about twenty years now. About three years ago we noticed a family of Coopers Hawks in the area. The next year – they built a nest in our Sycamore tree and soon there were two young hawks frequenting our bird bath. It’s not just the hawks – we are seeing a growing population of Owls in the area as well. Fascinating,
Yes, this is certainly true with us! After two weeks of recording birds for the Cornell bird feeding study, we stopped feeding the birds because of an aggressive Coopers hawk who not only took a Goldfinch from a window feeder, bur quite happily sat directly above a feeder waiting for the birds to come. When we went to the window to count birds and not one was in sight, we sometimes found a Cooper’s sitting in a nearby lilac bush or in a maple tree close by. We eventually put one feeder inside a bush that the little songbirds would use, and only partially filled it, so one one would linger there too long!
Cooper’s in NC TX are hunting wild ranging flocks of Rock Doves quite proficiently. Witnessed. Suburban hedges form good cover for small birds near feeders, but I have seen Sharpshins perch nearby & flush songbirds from one side of hedge to the other, wing over the hedge & take a prey on the far side. Great news for Accipitees either way!