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Crows slowly making comeback in Illinois
(POSTED: 3/8/10) Lee Ramsey, a retiree who volunteers for the Bird Conservation Network, keeps a feeder in his backyard, a once-popular destination for crows in winter.
Although Ramsey hasn't seen a single crow in his yard in Northfield for the past few years, he has hope that they are on their way.
"This year is notable because people have been seeing crows in flocks, small flocks, for the first time since the West Nile virus came through," said Ramsey.
The big black birds were killed off in droves in 2002, and all but disappeared from some neighborhoods in the Chicago region.
But many wildlife experts now say the crow is making a comeback, albeit a slow one.
"One possibility is that they're evolving to have immunity to the disease," said Mike Ward, an avian ecologist at the Illinois Natural History Survey.
Either way, the crow population has "popped up a little bit over the last couple of years," said Ward, who also is an assistant professor at the University of Illinois' department of natural resources and environmental sciences. "But it's still less than half of what the population was before West Nile virus hit."
In a U of I study in 2002, more than two-thirds of the crows monitored died. All the deceased birds tested positive for the virus, according to Sarah Hamer, who worked on the project as a graduate student and now works at Michigan State University.
"Very few birds that we took blood samples from, I think about 3 percent, had anti-bodies," said Hamer. "Meaning that, very few birds were being exposed and surviving."
Northwestern University's campus in Evanston used to have a lot of crows. Tim Spahn, the university's grounds services supervisor, said people often complained about the mess the crows left around campus. And when the West Nile virus struck, there were a lot of calls about dead birds.
While Spahn has been seeing crows again, they are not as much of a hassle. "I haven't had those calls, for the dead birds, and the problem areas haven't been as prevalent," he said.
Carol DiLorenzo, rental coordinator at The Grove nature center in Glenview, said there were a few years when she did not see or hear the noisy birds, which used to be there all the time.
Because The Grove is a preserve, it does not spray to kill mosquitoes, which spread the virus. DiLorenzo said that's one of the reasons crows were badly affected there.
"Last summer, I noticed a few [crows] and started to hear them a little bit, where I hadn't seen them at all," said DiLorenzo. "So that was exciting."
While other birds also were pummeled by the virus -- including chickadees and blue jays -- a lot of attention was paid to crows because they are more conspicuous, said Dave Willard, collection manager of the bird division at the Field Museum.
Although there is agreement that crows are repopulating, no one seems to be able to say at what rate. According to Willard, this is because there was not much of a record to begin with.
"I don't know how good our numbers were before West Nile even," he said. "That's the other problem with some of these things, because nobody really anticipated that we'd really need a baseline to compare it to."
By Michaela Ehimika, for ChicagoWildlifeNews.com
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