Staring out the window by my desk years ago, I watched a Cooper’s hawk fly down the alley just feet off the ground, bank sharply and fly to our backyard maple, where it plucked a woodpecker off my suet feeder so adroitly the wire basket didn’t even bounce.
Before you get too carried away with perfection of nature, the same winter I watched a Cooper’s hawk fly low down the alley, turn and smash into our big wooden feeder, a lifetime wedding gift from Jeff Wyse and Sheila O’Neill. It hit so hard it knocked itself out, as in flat on its back.
I stared for a minute, then thought, “Sheez, guess I should check on it.” As I came around the corner of the house, it stood, shook itself like a wrestler on WWE’s “Friday Night SmackDown,” then flew off.
Cooper’s hawks have a surprising history in Illinois, one I did not realize but found out when I sought more information to answer an interesting observation/question from George Johnston.
“I live in Orland Park and have noticed a huge increase of red-tailed hawks/Cooper’s hawks in the last year and a half,” he emailed. “Is the population increasing? They are sure feasting on small birds, squirrels and rabbits the last few months.”
Though I live south of Johnston, I would agree with him from personal observation. And in the other direction, Ron Wozny sends me photos every few months of the antics of the Cooper’s hawks (“Alice”) by him on the Northwest Side.
Personal observation is a good starting point, but actual facts still matter. So I emailed Doug Stotz, senior conservation ecologist at the Field Museum.
“Both red-tailed hawk and Cooper’s hawk are species showing long-term increases nationwide and specifically in Illinois,” he emailed. “According to Breeding Bird Survey data, red-tails have increased about 2.5 fold since the ’60s in Illinois, while Cooper’s hawks have increased nearly 10-fold across the same time period.
“Looking at my own personal records, I’ve seen about 50 percent more Cooper’s and 33 percent more red-tails compared to the early 2000s. So I would say there are definite recent increases in both species at a number of scales.”
I would say anybody who spends serious time outdoors has already intuited that.
Then Stotz gave more context.
“Whether there is a detectable increase in a specific area across a year or two is a different question,” he emailed. “For large raptors, you can definitely get that, where because of an explosion in rodents, rodent-eating hawks and owls become noticeably more abundant one year to the next. It is that rapid increase/decrease of their rodent prey that drives the irruption years of snowy owls. Similarly at Dixon Waterfowl Refuge, there are years when vole numbers are noticeably high, and you see populations of hawks and owls respond, specifically rough-legged hawks, northern harriers and short-eared owls, but also red-tailed hawks to a more limited degree.
“So it is possible that there could be a noticeable bump up in red-tail numbers this year compared to last at a local scale, grafted onto a long-term increase in the species. Because Cooper’s hawks largely feed on birds, rodent numbers don’t really matter to them. Bird numbers don’t tend to have these big cycles that rodents can have, so I wouldn’t expect that Cooper’s hawks would show a large single-year increase related to a big increase in food supply.
“My guess is that this is the long-term increase becoming progressively more noticeable. For me, at least, I find that I don’t really notice anything happening, but then suddenly think that bird has gotten way more common or way rarer. When I investigate, I find that the time frame for that increase or decrease is over at least several years.”
Again, if you are somebody who spends serious time outdoors, you know Stotz is right on there being a tipping level in observations. I’ve followed a fairly regular deer-scouting route that noticeably dropped off in numbers over the years, and when I checked with a taxidermist I know who follows a similar route and keeps notes on his observations, he had the figures to back up the drop in deer in that area.
Now, back to the surprise of Cooper’s hawks in Illinois.
“Cooper’s hawk is a classic example of that,” Stotz emailed. “When I arrived in Illinois in 1982, it was on the state threatened list. It was taken off pretty soon after that, but it isn’t until recently that it feels like you are seeing them ‘all the time.’ Adding to that with Cooper’s hawk is that the species has either learned how to coexist with humans in residential areas, or as those residential areas have more and older trees, the habitat is more appropriate for Cooper’s hawks.”
That’s why I ask.
