Monday, February 25, 2019

Roosting Crows: Birds of a Feather

American Crow Birds of a feather flock together. It’s a metaphor dating back to the sixteenth century; used even then in alluding to people with similar interests, motivation, loyalties, or like minds.

It’s also a straightforward reference to the fact that birds congregate with others of their own species. So, when I’m asked, as I have been recently, about the considerable numbers of crows that people have seen roosting in the village of Malone, I’m inclined to simply answer, ‘birds of a feather…’

Roosting is a period of inactivity for birds; a time of rest and/or sleeping. Almost all birds gather to roost; some in much larger groups than others. During the breeding season, birds are likely to roost individually or in small groups. But in winter, as food and shelter from the cold and predators become harder to find, spending their nights at larger, communal roosting sites lessens their vulnerability.

We often take pleasure in seeing chickadees, finches, or juncos congregating at our winter feeders. These birds are here all year round, but because they remain dispersed across the countryside throughout the breeding season and are not dependent upon our feeders for their survival, we’re far less aware of their presence and of their overall populations.

It’s no different with crows. Their presence, especially in and around populated areas, becomes more apparent as the communal roosting season begins, usually in late fall. It isn’t until the winter really sets in, however, that they gather together to endure the frigid nights in groups of anywhere from several hundred to several thousand birds; assemblages so large that we can’t help but take notice.

In urban areas, roosts of tens of thousands of crows are not uncommon. For example, a roost that has, at times, numbered 70 thousand crows has been documented in the town of Auburn, NY. Roosts of hundreds of thousands of crows have been documented in several Midwestern cities and one roost, at a site in Fort Cobb, Oklahoma, was estimated at two million! Rural roosts in excess of 100,000 crows have been documented in North America since the early 1800s.

No one is absolutely certain as to why crows gather like this, but there are probably a number of reasons. First is the simple fact that there’s safety in numbers. Cornell University ornithologist, Dr. Kevin J. McGowan, has called this the “wagon train analogy,” asserting that “crows are most afraid of large owls, and sleeping with a bunch of other crows could afford some protection for an individual crow.”

McGowan has observed that, “Crows will congregate in some area away from the final roosting site, usually an hour or two before complete darkness. Here the crows spend a lot of time calling, chasing, and fighting. At dark, the main body of the group will move toward the final roosting spot. Sometimes this final movement is relatively quiet, but usually it’s still quite noisy.” He adds that “The final roost can be a cohesive group in a single woodlot, or it can be rather diffusely spread out over a wide area of suitable trees.”

Food may be a big factor as well. According to Dr. McGowan, it may be that “roosts congregate around a large, non-defendable, reliable food source so, first thing and last thing in the day, food is available. It need not be the best food, but it is something to eat.”

Another of Dr. McGowan’s theories is that gathering allows individual, inexperienced birds that have not been very successful at locating forage, to “watch for other individuals coming in to the roost that look fat and happy; that obviously found some rich source of food. Then the hungry individual can… follow them out first thing in the morning to the good food source.”

It’s fairly easy to see how the village of Malone, which is surrounded by miles of extremely productive cropland, would give these birds, um, something to crow about. They’re able to readily leave their collective roosting site during the day to forage in nearby fields, along roads and in yards, returning in the evening to spend the night in the relative warmth and safety of the ‘wagon train.’

In spring, these large roosts will begin to break up as mated pairs (crows mate for life) return to their home terrain. Unmated birds may continue to use the roost for several more weeks.

Because crows are especially susceptible to West Nile Virus (WNV) infection, some people have expressed fears that crows may transmit the disease to people and pets. In fact, WNV is spread by the bite of an infected mosquito. There’s no evidence of the disease being spread directly from birds to humans.

Photo of American Crow by Kevin McGowan.

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Richard Gast is a retired Extension Program Educator and has been contracted by Cornell Cooperative Extension Franklin County to continue his informative and thought provoking articles.

9 Responses

  1. James Marco says:

    Well, Crows generally stick together. Not all birds do, though. I have seen Purple Finches mixed in with House Finches. Pine Siskins mixed in with Gold Finches, etc. And not all birds congregate. Most raptors are individuals or small family groups. Anyway, a good article.

  2. Norgrove Robert says:

    Thanks for all you do!
    The articles are always entertaining and informative. Once being part if the Adirondack is xperience when growing up. It brings me back to those memories when I read some of the articles you have published

    Thanks again

  3. Naj Wikoff says:

    About a week ago I saw a gathering of several hundred crows spread over two fields east of the Northway north of Plattsburgh. I was wondering what that was all about. Now I know. Thanks

    • Boreas says:

      Plattsburgh has been a long-standing winter roosting area. It can be kinda scary sometimes – especially for Hitchcock fans…

  4. geogymn says:

    In todays Utica OD;

    “USDA to apply bird pesticides in Chadwicks”

    • Indoorcatmom says:

      So sad. There must be a better way. In a world with increasing awareness of the loss of endangered species, genetic abnormalities and cancer caused by chemicals, it is difficult to believe we still resort to such “solutions”.

  5. TPR (@TPRjerks) says:

    It’s a nightmare currently. Some cars that I’ve seen… Yikes.
    I, too have not made it unscathed. I was śhìt on by at least one crow this Winter. Walking down the sidewalk startled them.

    • Boreas says:

      Crows are renowned for their persistence and accuracy…

    • Suji says:

      One crow crapped on your car? A nightmare indeed! Let that be the least of your problems, easily fixed by a trip to the car wash.