Waterloo Region Record

Opened your door to thousands of crows on the street? You’re not alone

Large gatherings of the birds seen around region roosting for winter, to keep them safe from predators

ROBERT WILLIAMS

WATERLOO First, you hear them.

The sounds of hundreds, sometimes thousands, of raucous “caws” floating down from the sky.

Then you see them, a sea of black, landing on tree branches and rooftops in every direction.

Is this murder of crows normal? Photos and videos of the mass gatherings in Waterloo Region have been making their rounds on social media, with hundreds, possibly thousands, of crows frequenting a spot near Erb Street West and Westmount Road. For years, these mass gatherings have become common sites at the University of Waterloo.

While it may seem like a scene out of an Edgar Allan Poe poem, opening your front door at dusk to a street full of crows is not a cryptic omen of death at your doorstep.

It’s just winter living in a North American city in the 21st century.

“It’s a communal roosting event that the birds do,” said John Marzluff, a professor of wildlife science at the University of Washington and one of the world’s foremost experts on crows. “There’s a town by me where there’s up to 10,000 that do it every night. They’ll be lined up on the fence, trees and

buildings before they go into a final roost spot.”

These meetings of the crows are happening in cities across North America, explained Marzluff, occurring every year as the weather starts to get colder and the nights longer.

The crows are roosting together primarily for safety, he said, staying away from owls and raccoons, which are often their biggest predators at night.

The spots aren’t picked at random. Roosts are typically spaced about 50 kilometres apart, with all the crows within that area coming to spend the night together in a centralized spot.

“They’re probably doing a lot of cool socialization that we don’t really understand,” said Marzluff. “They certainly make a lot of noise, they’ll be grooming, they’ll be eating a little bit, but mostly they’re coming in for a safe space to spend the night.”

Gathering spots are always off the ground, sometimes on buildings or bridges, but often in trees.

“If crows find a safe and comfortable spot, they will continue to use it until conditions change,” said Jason Bracey, a volunteer with Rare, the charitable research reserve in the Blair area of Cambridge. “They will disperse during the day into smaller social groups before returning at dusk.”

During the day, these crows are often scavenging out in farmland in search of food. Depending how far they get, they could return at night for the roost, or join another in the nearest city or town.

They split into smaller family groups during breeding season in the spring, said Bracey, but when summer is over and the cold weather arrives, that’s when the “parties” begin.

“Winter is the time when all the birds join the roost because they don’t have a nest to be taken care of like they would have in the spring and summer,” said Marzluff. “And as our cities have become warmer and larger, that’s attracted more crows to be able to stay the winter.”

The American crows that populate southwestern Ontario were traditionally migratory, he said, following the expansion of farmland north during the 1800s. Initially, said Marzluff, the scattered farmhouses would not have been enough to sustain them over the harsh winter months.

As cities have grown to provide sustainable year-round living conditions, more have been able to stay for the winters and become permanent city dwellers.

In general, winter roosts don’t pose any real threat to people outside of the potential spread of disease. If the birds are out in farmland that has cattle, for example, they can pick up antibioticresistant material on the farms and bring it back to the city in their poop. Hypothetically, said Marzluff, they could also spread bacteria, such as campylobacter or E. coli.

“It’s basically them bringing back what we put into the environment back to us,” he said. There’s also been examples of crows spreading West Nile, though it isn’t very common.

But while the sound and bird droppings might be irritable at times, there is a very important reason to be a friendly neighbour to the crows — they remember faces.

“If you shoot one or throw a rock at one or pick up a dead one you happen to see, the other birds will see you as a potential threat, they’ll give some scolding alarm calls, and they’ll all gather around you and cuss you out,” said Marzluff.

As they’re doing this, they’re learning that you are a dangerous person, they’re memorizing your face, and they will harass you “much longer than you would like.”

The University of Washington has been running experiments on facial recognition for 16 years, he said, and the crows still remember the face of the man who first caught them.

“Ultimately, you really don’t want to mess with them because that will be more of a problem than it is worth,” Marzluff said.

Some of the crows in their study are more than 20 years old, he said, living a long life and learning a great deal over that time that is passed down to the next generations.

In Japan, Jungle Crows have learned to place nuts under car tires to break the hard outer shells. And in New Caledonia, the local crows make tools out of sticks and stones to carry out tasks.

So, don’t get spooked if you own a new home and they start showing up seemingly out of the blue.

“This isn’t just a random crow coming by, this could be a bird that’s lived there longer than you have, and they may have strong ties and knowledge about the area. They’re a neighbour just like anyone else, and they’re a smart one at that.”

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2022-01-20T08:00:00.0000000Z

2022-01-20T08:00:00.0000000Z

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