A Murder of Crows

In my downtown neighborhood of Sherman Hill, and in many areas around Des Moines, an annual phenomenon is in full swing; the roosting of the crows.

As dusk falls across the city, the sky begins to fill with streaks of black.  It starts off with just one or two birds, suddenly appearing as if by magic.  As time passes and the light begins to dim, you will notice more and more large black birds winging across the evening sky, and alighting on two or three trees in your neighborhood.

For the hour or so before dark, the crows will emit a cacophony of sound as they fly from tree to tree, squabbling amongst themselves and calling out to their neighbors as more birds join the flock.  By the time the sun is sinking below the horizon, their noise can drown out all other neighborhood sounds.  But at nightfall, as if by an unspoken signal, they settle down and gradually fall silent.

During the spring and summer months, breeding crows spread out across the countryside to raise their young.  They are fairly territorial during the breeding season, and will defend against all comers beyond their family group.  As the fledgling chicks leave the nest, and summer deepens into fall, the birds start to move in towards a centralized sleeping location, known as a roost.

There are several theories as to why crows like to roost in such large numbers during the colder months.  The most popular is the concept of "safety in numbers".  Owls love to prey on sleeping crows.  By roosting in large flocks, full of watchful eyes, they have a better chance of seeing their predators and avoiding their deadly talons.

Another idea is that there are some trees that are simply ideal for sleeping; five star bird hotels, if you will.  The crows don't mind sharing those trees with other birds if it means that they get a bed in the best tree in town.

Because crows are highly intelligent and good communicators, another theory has them sharing information at the nightly roost.  For example, a bird that has had a hard time finding food for a few days might pick out another bird that seems to be in good health, and follow them to their food sources for the next several days.

Roosts of crows are a natural and global phenomenon.  The largest recorded roost to date , located in Fort Cobb, Oklahoma, held over two million crows.  Take some time to observe and appreciate these large congregations of our wild neighbors.  Send in your photos and your observations!