CHICAGO — Look hard enough and in the right spot, and you're bound to see a rare black squirrel within Chicago city limits.
Black squirrels, which are actually mutations of the far-more-common gray squirrel, represent far less than 1 percent of the city's squirrel population, which numbers in the hundreds of thousands.
That's according to University of Illinois at Chicago distinguished professor of biology Joel Brown, who's also the founder of Project Squirrel — a citizen-based science project that allows individuals to track and observe squirrels in their backyards and elsewhere throughout the country.
"They do show sustained and persistent populations within the city," Brown said. "But black squirrels probably represent about 1 in 10,000 of the squirrels in Chicago."
The most common places to find black squirrels in the city are the University of Chicago campus in Hyde Park, the Loyola of Chicago campus in Rogers Park/Edgewater and Welles Park in North Center/Lincoln Square. There are a few of the black squirrels at UIC and in Norwood Park, Brown said.
Brown said the black squirrels thrive better on college campuses possibly because they get fed by humans and the campuses are safer for the squirrels from "urban harassers" like coyotes, hawks, cats, dogs, foxes and other predators.
Brown and Steve Sullivan, his student and the co-director of Project Squirrel, said black squirrel populations grow in colder climates. For example, Brown said black squirrels represent about one third of Toronto's squirrel population, while at Illinois Beach State Park on the Illinois-Wisconsin border, black squirrels make up about 10 percent of the population.
Black Squirrel, another rare Chicago wonder, like a friendly bartender or ketchup on a hot dog... pic.twitter.com/ZNkN1LalgW— Jay Cunningham (@zcrom) October 20, 2015
Brown described Chicago as an "urbanistic game park" with its flying and ground-based predators, and those squirrel hunters will likely keep the city's black squirrel population very finite.
"If black squirrels stand out to people, they will definitely stand out to predators, too," Brown said.
Brown said gray squirrel mutations also include an extremely rare white squirrel. In the 20-plus years since founding Project Squirrel, he's seen one white squirrel in Chicago and received about five reports of sightings. He and Sullivan said natural selection weeds out the white squirrels, which stand out even more than black squirrels to predators, keeping their numbers in Chicago almost nonexistent.
"Black squirrels have a higher likelihood of surviving than whites because they are more camouflaged and less susceptible to sun damage," Sullivan said.
There are some larger white squirrel populations in the United States, including in Downstate Olney and Oberlin (Ohio) College. Oberlin's mascot is the "White Squirrel."
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