A murder of crows gather in the treetops along Kenduskeag Avenue in Bangor, Maine, in 2022. Credit: Courtesy of Bob Duchesne

I probably don’t need to tell Bangor residents that every evening a large flock of crows gathers along Kenduskeag Stream. A very large flock. Maybe the biggest flock yet.

The flock moves around a bit every year. Two years ago, the crows settled around Mount Pleasant Cemetery for much of the winter. Last year, many congregated near the Veterans Remembrance Bridge, on the Brewer side of the Penobscot. This year, the mass murder of crows apparently prefers the neighborhood trees on the lower end of Kenduskeag Avenue.

Communal roosting is not new, and crows aren’t the only ones doing it. Pigeons habitually gather on the rooftop of BJ’s near the Bangor Mall. European starlings form large swarms around the mall. Scores of house sparrows gather in bushes throughout the Queen City. Gulls and waterfowl flock up in winter, too. The same thing is happening in densely populated areas throughout Maine. Why?

The big reason is “safety in numbers.” Larger birds fear eagles. Smaller birds fear hawks. Crows fear owls. They all roost in places where they can see trouble coming, or where predators have a hard time swooping in. Pigeons sleep under bridges. House sparrows inhabit the inner branches of thick bushes, where a raptor risks impalement if it attacks. In all cases, a group of birds is more likely to spot an approaching troublemaker than a solo bird would. A mallard roosting alone on an ice floe is literally a “sitting duck.”

Math favors birds in a flock. If a predator hunts a lone bird, that bird is 100 percent likely to be the target of the attack. But if you’re one of a thousand birds, the odds are 99.9 percent that the victim won’t be you. There’s even evidence that birds in a communal roost jockey for position, pushing toward the increased safety of inner branches, leaving the outer branches to younger, meeker birds.

Still, crows could get those advantages elsewhere. Why are they moving into town?

Cities are a tad warmer in winter, and urban lights may better illuminate approaching danger. Crows forage more on human-generated food in winter. Garbage, roadkill and discarded food morsels are dietary delights for crows. Crows are social, and there is evidence that they share information with their flocks. Crows likely notice which birds are fat and happy in the evening, then follow those successful birds the next morning.

The crows scatter at daybreak. Some go to the mall. Some forage through residential neighborhoods. Many head for hay and corn fields, scavenging through the stubble. Many fields are only a few miles out of town, as the crow flies. In late afternoon, you can watch thousands stream back to the roost from all directions.

Crows have always been communal roosters. However, huge city flocks are a relatively recent phenomenon. Hunting may have something to do with it, although it’s difficult to draw a conclusion. It may be that crows have learned to fear people, and recognize that they can’t be hunted in town. Canada geese have certainly figured that out. They often gather in municipal ponds in autumn, especially in Aroostook County.

Or perhaps it’s the opposite: crows could be losing their fear of people. Humans have a long history of shooting crows. Until recently, crows avoided population centers. Even today, there are extensive hunting seasons for crows in Maine, with no bag limit on the number that can be harvested. But Maine’s hunting culture has changed. A century ago, birds were blasted out of the sky just for sport, or because they were considered pests. Modern hunters largely focus on killing only what they are willing to eat. With less to fear from hunters, crows now seek the advantages that urban areas offer.

One thing’s for certain. In winter, crows largely abandon the forest. The Maine Department of Inland Fisheries and Wildlife is on track to complete its fifth and final season of a winter bird atlas this year. I’ve spent much of the last four winters in the deep woods, surveying birds. I can go days without seeing a single crow. Crows disperse to breed in the summer, and the woods are full of them. But in winter, they flock into town.

Incidentally, crows are edible. You can find recipes online. All recipes seem to have one thing in common, regardless of whether they advocate cooking in dressings, oils, or fruit sauces. Every recipe seeks to remove as much crow flavor as possible. So much for “eating crow.”

Avatar photo

Bob Duchesne, Good Birding

Bob Duchesne serves as vice president of Maine Audubon’s Penobscot Valley Chapter. He developed the Maine Birding Trail, with information at mainebirdingtrail.com. He can be reached at duchesne@midmaine.com.