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 a tree cylinder feeder in front and a trap door feeder in back and even with 7 or 8 inches , I don’t see as many sparrows asI used to . I see some nuthatches , juncos, chickadees , occasional red breasted woodpecker , and cardinals . The small ones go from my evergreen bushes and the feeders ,they are very watchful and nervous . l’m suspecting our smaller hawks we have in this area , once I saw a Peregrine Falcon , Great Horned Owl and a Red Tailed Hawk . Seems there are less sparrows and smaller birds here too !
Makes a lot of sense
I had thought that the recent influx of Cooper’s Hawks in our neighborhood was due to a very steady supply of squirrels.
The squirrels consume a large percentage of the seed we put out for the birds!
There is a Coopers Hawk that patrols my neighborhood. I have seen him take a mourning dove and another bird. He has also drank and cleaned up in my bird bath. Red Tailed Hawks are also seen regularly in our neighborhood. We have seen them take two squirrels and three sea gulls.
Great article. A Cooper’s Hawk has exploded from the bougainvillea in my front yard exactly as you described, on more than one occasion, except it typically leaves with a sparrow in it’s talons. The first time I witnessed it I was amazed given that I live in downtown San Diego.
Hello Mr. Miller,
Thanks for an interesting and well informed article. One element which I thought would have been interesting to discuss is the question of how to resolve the conflict at the bird feeder, beyond the explanation why it has developed. At least in my backyard, in Atlanta, Georgia, that has become a really big question: do I attract all of my nice variety of birds to keep the hawks coming and moving into my backyard or do I stop feeding to prevent the hawks from decimating the backyard bird population – and it is not just sparrows? How to strike a balance and what to do from a researchers point of view – that is the question.
Thanks, Klaus
Hi Klaus,
Thanks for your comment. I know that many backyard bird feeding enthusiasts have similar questions. I think a lot of this is a personal choice, but I’ll offer one perspective. The backyards of urban and suburban areas are an ecosystem. There are predator-prey interactions there just as in a “wilder” ecosystem. Predators play an important role. The abundant bird feed and backyard habitat actually creates abundant populations of many bird species. The hawks feed on that abundance. I have not seen any evidence that they decimate songbird populations, especially not on any larger level. That said, my neighborhood birds use the abundance of cover (shrubs, hedges, etc) to evade hawks. Not all do, but it certainly protects most of the birds. Our front yard consists largely of native vegetation, which the birds and other wildlife really use. Thanks for writing. Matt
Last July, as we were enjoying the many hummingbirds at our feeders on our front porch at our ranch in Texas, they all quickly scattered except one. That one hummer was stunned and knocked to the ground by a Cooper’s Hawk swooping in, as it flew off the feeder. The Cooper’s Hawk then picked it up and flew off. Not long afterwards, we saw a Cooper’s Hawk in a tree nearby watching, and he then flew in again to repeat his “hunting”. We were appalled yet excited. We realized we created a trap where the hummers were “sitting ducks” and being “picked off”, and that made us sad. But we were enthralled as well, because it was very cool to see the hawk do what he does naturally in nature, which is hunt. Even though we were very glad to witness nature at its best, after the second loss of our little friends, we did take down the feeders. We will resume again this summer, however!
In November, a hawk landed on my deck in the Lakeview neighborhood of Chicago. After I Googled and identified him as a broad winged hawk, I read that he is a migrator and this was out of season. So was he lost, or did he overstay because of the good pickings? First time I’ve seen this, although other Chicago friends have had hawks at their bird feeders too.
We the hawks in our western Chicago suburb. It’s not all that unusual to see one perched on my lawn furniture, as I did the other day. I’m not sure if they’re Cooper or red tail, but they are beautiful. And yes, I do have several feeders in my yard.
Several years ago, from ’95-’02, we lived in the Ahwatukee area of Phoenix, AZ. I had bird feeders and a bird bath in my backyard.
The first winter I noticed a Coopers Hawk in the bird bath. It came every day to bathe. (Once I timed how long it stayed. 1 1/2 hours!) That hawk returned every winter for 7 years. I never once saw it take a bird from my yard, but they did make themselves scarce when it was there. I loved having it there.
A very large hawk landed in our cherry tree on our front lawn several weeks ago. Unfortunately, I do not know the specific type, although I did take a picture of it. We live in a typical suburban development in Rochester, NY. This is only the second time we have seen a hawk in our yard in the thirty some years we have lived here. The other one landed high up in the ash trees of our back yard a number of years ago. It was fascinating to read above article about increasing number of hawks in urban environments. For many years, we have seen hawks perching on the lamp posts along the superhighway that goes around Rochester and all its’ suburbs.
Thanks for confirming my suspicions that the weekly visit of a pair of coopers hawks to my feeders, as well as increased regular sightings of Red shoulder hawks, Red tail hawks, occasional Sharpie or Merlin etc in suburban and urban areas has increased over the past thirty years. Enjoy your articles!
Thanks Michelle. I am glad you enjoy the articles.
Your observations surely seem to fit with what we are seeing here in Champaign , IL. A Cooper’s hawk has dismembered a pigeon while sitting on our swing and left the bones picked clean. We see the hawk fairly often as it swoops in to grab songbirds very close to our dining room windows.
Your article is most interesting. A few years ago I watch a sharp shinned hawk spend about 30 minutes in pursuit of the chickadees, and tufted titmice in our tri-colored beech tree. He or she went away hungry. We also have a nesting pair of red tailed hawks at the end of our street. They make quite a few passes by the feeders and I find several scattered mourning dove feathers in the yard from time to time.
Last week we didn’t just have two red tail hawks we had two eagles.
Thanks for the comment, Pam. Bald eagles have definitely become a more frequent sighting in many parts of the country. (I see them flying over my backyard, too!). It is a great conservation success story.
Hello! I have a backyard bird feeder in San Luis Obispo, California. The Cooper’s Hawk has appeared here this winter! The frequent visits are new at my feeder! I attribute the appearance to the fact that acres of uncultivated fields close to the mobile home park where I live were recently developed into dense housing tracts. I’m sure the former hunting grounds were full of ground squirrels, mice, rabbits, quail, lizards, snakes, and gophers. Quail have appeared here and the hawk! It’s exciting to witness the hawk in such close proximity, when it’s diving into the birds’ hide out bushes, perching on the fence, on the railing of my porch, sitting on the neighbor’s roof, or generally flying through the neighborhood. Sometimes I sit with my binoculars and stare at the beauty of the hawk as it sits on the fence in close range.