An hour before dusk, the crows soared south to their roost.
Hundreds of silky black birds swept past Dunn’s Woods, settling among the treetops of First Street and Highland Avenue.
They clustered along branches as the restless continued to circle the houses, wrapping the neighborhood in their raucous chatter. Their caws crescendoed, blotting out all other noise, then gently fell to an excited hum. Sometimes, a loud car engine would jolt the birds from their rest, sending them once more into the sky.
Crows have been drawn to Bloomington’s mix of urban heat, light and its proximity to the countryside for over a decade. Much like Indiana University’s own students, many of Bloomington’s crows are likely young adults who have traveled across the continent to explore the next chapter of their lives, according to an expert.
Each winter, the murder looms above the city, generating both unease and awe.
Dawn Hewitt first saw the black spirals of crows converge on Bloomington in 2008.
A former Herald-Times journalist who left to become the managing editor of Bird Watcher’s Digest, Hewitt described the skies as filled with “thousands of black marbles.”
“It was a spectacle the likes of which I had never seen or imagined,” she said.
Hewitt wrote about the crows for the HT the same year, embarking on a journey to discover where they go at night. Nearly two decades later, Hewitt said she found they don’t roost at the same place every night, sweeping past used-car lots, parking garages and the trees at Seminary Square.
Covering the birds gave her a new appreciation for crows, she said, describing their bill-clacking and cawing as conversational.
“Crows are coming from all over the Midwest to spend the winter in Bloomington,” Hewitt said.
Kevin McGowan, a senior associate at the Cornell Lab of Ornithology, has spent much of his career researching the American crow.
When deciding where to roost, crows prefer urban areas because of their heat island effect but require trees to roost in and a food source, McGowan said. Bloomington, with its greenery and ample countryside, allows crows to spend the day foraging in agricultural areas while returning to the city at night.
However, a critical factor for crows are city lights, which allow the crows to remain alert for their single greatest predator next to humans — the great horned owl. While the owl can see in the dark, crows, like humans, need light to guide the way.
“To them, the owl is the boogeyman,” McGowan said.
Many Bloomington residents have marveled at the sheer number and concentration of the crows. But the latest numbers of the crow population, according to a 2016 study from the U.S. Department of Agriculture, found 13,000 crows in the city at one time — a small roost according to McGowan, who said the largest roost he’s seen was 100,000.
The crows’ habit of flocking is somewhat strategic because it protects them from predators, but their cawing and chasing behavior prior to roosting is also social, McGowan said.
Crows are some of the smartest animals in the world. In fact, crows can recognize individual human faces and remember those faces for years.
McGowan has personal experience with this ability, recalling that the crows hated him at the beginning of his study until he began feeding them peanuts. Once they associated his face with the peanuts, McGowan said, they began to chase his car down the street in anticipation of the nuts.
They also communicate danger to one another; McGowan said different nests of crows would react to him even when he had not been there before. It functions a bit like a neighborhood watch system, he said.
McGowan said the crows come from a variety of places. A roost may include hometown crows, crows from a nearby town or those who have journeyed as far as Canada. Crows who are breeding tend to stay in town and settle down, while young adult crows may fly across the country to explore, he said.
While the flock of crows appears large visually, their numbers have declined in recent years. McGowan said the crow population was reduced when the West Nile virus hit in the early 2000s.
Their presence in cities is also a recent phenomenon. McGowan said crows across the continent suddenly began migrating to cities in the late 1980s and ‘90s. Crow-human interaction is partially a consequence of a change in attitudes toward wildlife, which invited protection legislation for birds and other animals.
“We’re making the world better for birds, and they’re taking advantage of it,” he said.
Some have speculated that Bloomington’s crows originate from nearby Terre Haute. In 2009, Terre Haute, which had roosts of 58,000 in its peak, employed a crow management plan to force the roosts into the countryside. From there, they may have relocated to nearby cities like Bloomington; McGowan, who has witnessed a similar movement in New York, said the theory was feasible.
The USDA study conducted in 2016 found crows roosted mostly on the east side of town, appearing between East 17th Street and Law Lane along North Eagleson Avenue for three nights — the highest frequency of all the identified roosting locations. Staging and pre-staging locations, defined as areas where the crows gather 30 minutes to two hours prior to roosting, were more evenly distributed across the west and east sides of town, although College Mall and the Pfau Course at IU were the most popular spots.
An informal poll conducted by the IDS found crow sightings were concentrated south of campus, closer to the west side of town.
Recent crow sightings in Bloomington
Although other cities with winter crow roosts have employed management efforts, Bloomington has mainly taken a hands-off approach. But in 2016, the city discussed potential mitigation plans with CFC Properties, Downtown Bloomington Inc, IU and the county. IU has its own deterrents, including sound devices from Birdx that dissuade crows from roosting on campus by emitting fake bird noises.
Despite attempts to silence the birds, some IU students get excited about the crows.
IU junior Ella Scheper said she was studying for a final with a friend in early December when she saw the crows. She stood at the window of her Henderson Street apartment for ten minutes, she said, watching the creatures fly over First and Second Street.
The sheer number of the birds was the most shocking to Scheper, who doesn’t recall seeing such a phenomenon in her hometown of Covington, Kentucky.
“I’ve seen flocks of birds before, but this just seemed almost unreal,” she said.
The crows pass Scheper’s window right around sunset and up until it’s dark, she said, but she isn’t bothered by their presence in her neighborhood.
When she watches them, she wonders where the birds go during the day and where they spend their time when they aren’t wintering in Bloomington.
While some consider them a nuisance, the downsides of the birds are few. Crows carry some diseases, McGowan said, but you would have to lick the streets to become infected. In other words, it’s not easy.
“One good daycare spreads more disease each year than any of your crow roosts would ever do,” he said.
In fact, crows can be beneficial. When the birds gather food from neighboring fields, they consume nitrogen and release it through poop in the cities. These deposits create nitrogen hotspots that remain after the crows are gone, McGowan said, leading to improved plant and tree growth.
But the biggest benefit of the crows is the awe they inspire, McGowan said.
He referred to the story of the passenger pigeon, once one of the most abundant birds on Earth, which would gather in massive flocks and darken sky for hours.
But human hands ultimately drove the bird to extinction in the early 1900s, namely through hunting and deforestation.
When McGowan sees the crows swarming otherwise gray winter skies, he thinks of the passenger pigeon. The crows inspire a similar kind of awe.
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