Wednesday, December 19, 2012

Crow roost

I found myself in this spot, in rural Jackson County, Ohio, last Saturday at twilight. I was down there to cover my turf for the Beaver Valley Christmas Bird Count, so-named for the sprawling metropolis of Beaver several miles to the south. That forested ridge across the field is one of many in the area. The topography of this immediate region still shows the effects of a massive river system long obliterated by past glaciation. The mighty Teays River, which arose near the present day Great Smoky Mountains National Park, coursed northward and into Ohio. Its main channel and side tributaries left behind broad flat valleys, such as above, interspersed with sharp ridges.

If you are an American Crow, these razorback ridges make great roosting spots. The birds can see everything for some distance in every direction, and potential enemies have no chance of sneaking up undetected. Click the photo to expand it. All of those specks are crows, and this is but one tiny part of the local roost. Such an aggregation of crows is known by the sinister term "a murder of crows".

Crows have roosted in this immediate vicinity for a long time, probably as long as I've been doing this count and that's been 15 years or so. It's a spectacle, watching all of the birds return from far and wide at sunset. The air is filled with a cacophony of caws as the birds greet each other and otherwise interact, constantly jabbering as crows will do. Occasionally a collective nervous tremor ripples through the flock, and they briefly rise into the sky as of one mind, their chatter rising to a fevered pitch and totally dominating the surrounding landscape.


This video offers a mild taste of the ambience of the roost. I did not reach the roost site until a great many of the birds were already in residence, and didn't have time to thoroughly explore the area to tally the roosting zone in its entirety before nightfall. I turned in an estimate of 7,000 birds, but there are far more than that in the area. Next year I intend to get to this spot sooner, and attempt to make a more accurate accounting of these crows.


Rick from Licking said...

Do these large murders of crows only occur in winter and why. Here in Licking Co,there are a large group that flock around the trees of the Heath Mall at night.
In the 20acres of white pines next to our home,we have thousands of starlings,grackles,few redwings,and robins that roost every night. Every evening the stealthy coopers come flying in,can they catch on the wing?

Jim McCormac said...

Hi Rick,

Yes, these "murders" form only in the winter, and crows roost communally in part for protection, mutual exploitation of ideal roost spots that are near excellent foraging grounds, and because they are just highly social birds.

And yes, Cooper's Hawks assuredly can catch blackbirds on the wing.

Curve-lined Owlet: A most extraordinary caterpillar!

  A typical Ohio woodland, especially in southern Ohio's Adams County, where I made this shot. The leaves in the foreground belong to Co...