At this time of year, crows increase a different kind of murder rate

By Sharon Stiteler

Sharon Stiteler runs Birdchick.com and wrote the books "City Birds/Country Birds" and "Disapproving Rabbits." She leads bird trips, does bird surveys around the country and works part time as a national park ranger.

Depending on where your evening commute finds you around the Twin Cities, you may have noticed some large dark birds flowing toward downtown Minneapolis like a rolling river. The closer you get to the southern edge of downtown Minneapolis, the larger the congregation grows, with American crows flying in from all directions, the flocks wheeling and spinning from tree to tree.

Eventually, they settle down a bit and try to sleep on any available perch, from branches to the tops of buildings. Though some might see this as an unsettling omen, these birds are doing what they should be doing: roosting.

American crows are generally social birds. Family groups spend the year together and siblings from the previous year even help their parents raise young. In the winter, that social nature gets extreme. From mid-November through early March, crows form gigantic flocks to sleep in a certain area; these are called roosts. The flocks are frequently referred to as a murder, perhaps because that's what some people would like to do when they discover their car covered in crow droppings the next morning.

These boisterous birds have always formed large winter roosts, but American crows choosing the south end of downtown Minneapolis is relatively new. If you think of it from a crow's point of view, sleeping in the city has its benefits. For one thing, the city will be warmer than rural areas. Buildings and roads retain heat better than trees and water. The temperature in an urban setting can be 10 degrees warmer than in the surrounding countryside.

The other advantage is there's less disturbance to the flock. In rural areas, American crows can be hunted. Even out of season, a landowner in the middle of nowhere may not want a large crow roost on his property and make noise to get the birds to move on. Because of firearms laws, crows generally aren't shot at in urban areas.

Ample food can be found in the Twin Cities metro area, from garbage in back alleys to the numerous hackberry trees that line the streets. The tiny, hard berry is a source of food for many species in the winter, and crows love them.

If you have ever passed under a winter crow roost, you may wonder if it's worth it, as the crows can be quite noisy and chatty late into the night. But some crows stay awake to keep a lookout for marauding great horned owls. When the leaves are off the trees, there's no protection to hide a large crow. By being one of hundreds of thousands, you are less likely to be the one eaten that night. Great horned owls love to eat a little crow, and they start their nesting process in January. If you ever get the opportunity to look into a great horned nest, it will contain quite a few black feathers.

You can try to follow the roost at dusk by driving around and following the flocks streaming into the city. Before the crows decide on where exactly they will sleep, smaller flocks will come together to form larger flocks and feed together or hang out in the trees. This is called staging. At some point, that giant flock will rise and join the final roost. There's no official tally for the crow roost in Minneapolis, but some estimates put it at more than 500,000 birds.

The exact location of the Minneapolis crow roost shifts a little bit each night. Sometimes the crows descend on Loring Park; on other night's it's Elliot Park. Every now and then they branch out into south Minneapolis neighborhoods. Their presence has inspired a page called "South Minneapolis Crows: The Mega-Murder" on Facebook.

If you have a roost near your home and you've had enough, take heart. American crows will begin nesting in early March. The roost will soon break up.

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