Monday, November 1, 2010

The gleaners

A swarm of thousands of blackbirds take over the sky and woods surrounding a cornfield in Warren County, NJ.

"The Gleaners" (1857) by Jean-Fran├žois Millet. Peasant women pick up the left-overs of the wheat harvest. Note the flock of black birds in the background.

The combines have finally come through to harvest the cornfields, and now a plague of blackbirds has descended upon us. Thousands of blackbirds! Grackles, red-wings, cowbirds, and starlings.

They blacken the corn stubble with their bodies. They fill up the tree branches. They swarm and stream overhead. The air, fields and woods are a squeaking, creaking, chattering cacophony. It is quite exciting, really.

Why these four different species feel so comfortable associating together is a puzzle to me. On the ground, they form a pretty even mixture, all climbing over one another for kernels without segregation. And in the air, too, they fly up as a single terrifying superorganism when a red-tailed hawk makes a dive, or the neighborhood feral cat gets too close. A pretty effective strategy, I guess. But I wonder what a red-winged blackbird thinks of the grackle he's rubbing wings with. Not to mention the starlings, who aren't even related, and have only known these new world blackbirds for a mere fraction of a millennium.

Cowbirds, grackles, and red-wings jostle for position in the old sunflower field.

The flocks aren't singular, but are more like a huge patchwork multiflock. A thousand birds will be in the cornfield, another thousand in the trees, a few hundred down drinking in the creek, and hundreds more streaming in from parts unknown. Each contributes his own chatter and squeak to keep up the ambient din, the creaking soundscape. The patches are glued together by constant streams of individuals moving between them. These are the birds who have had enough of one activity, and are now inclined to partake in another. (Enough corn, time to bathe.)

Taking in the spectacle as a whole, it isn't too difficult to imagine the passenger pigeon hordes that must have descended on these same fields only a few hundred years ago.

The aftermath.

P.S. my wife just pointed out to me that all (or almost all) of the red-wings and cowbirds are males! Where are all the females?

P.S.S. see related post on snow geese.

1 comment:

  1. Interesting phenomenon Mike and a noisy one at that I bet. You have some great photos of these mixed flocks.

    According to Birds of North America Online "Winter roosts vary from a few birds to several million. Often segregates by sex and age in roosts and while feeding during day."

    Maybe the female flock is on another corn field?