I’ve spent most of the last week away from home, making my usual travels about Ontario. The morning that I left I got up unusually early (for me) and headed straight for the shower. When I got out I noticed a lot of chatter outside the washroom window. A few dark shapes swooped by, from the trees opposite to someplace down below. The washroom overlooks our side yard, but you can see a little of the front lawn from there; and on our front lawn were dozens of blackbirds. I hurried for my camera, but naturally it was downstairs and had the wrong lens on it. By the time I got it swapped out and returned to the living room window, most of the birds had departed, leaving just a few dozen in front of the house. They hadn’t gone far, though, just to the woods at the far edge of the meadow, perhaps a hundred yards away. So I slipped on my shoes and headed out with my camera.
I could hear them the moment I stepped outside. Blackbird flocks are remarkably noisy; it seems that every bird has something to say. Below their voices, though, was another sound. I might almost have guessed it for running water, if I didn’t know we didn’t live anywhere close to a burbling creek. I made my way through the dewy grass for the woods and peered through the branches. Sure enough: easily a hundred or more blackbirds, mostly grackles, shuffling through the leaf litter on the forest floor, the rustling of the dead leaves sounding like water.
The forest birds represented only a portion of the flock. The rest of them were foraging among the grass at the field, or in the lower branches of the woods’ edge. A foraging flock of blackbirds seems to be constantly on the move. The whole time I stood there birds were flying along the edge of the trees, always in the same direction, dozens at a time. They’d fly out from the trees, or up from the ground, forward a few dozen yards, and then land again. The flock rolls along like this, the birds in the rear leapfrogging to the front and foraging for a while until they’re again at the back. It’s really neat to watch because it looks like the flock never ends, with birds constantly rising up and streaming forward. This was why the birds passed through our front yard so quickly. It makes it hard to get an accurate idea of flock size, too, but I guesstimated there were at least a few hundred in this one.
Interestingly, the day before there had been a large flock farther back in our fields, hanging out in the treetops. It might even have been the same one. Blackbird flocks are often heard before they’re seen, which was the case with this one. Hundreds of voices make enough din to carry fairly long distances. These groups may serve one of a few purposes: congregations of waterfowl or shorebirds are often tied to localized food resources, and Canada Geese and other formation-flying species will travel together for the decreased energy costs of flight. There may also be an element of safety in numbers involved.
I’m not sure why blackbirds gather together in the fall. There aren’t very many species of passerines (songbirds such as the sparrows, warblers, blackbirds, etc) that will congregate like this; blackbirds (grackles, Red-wings, Rusties, cowbirds, and related) and starlings will flock together, as will swallows. Neither the Birds of North America account for Common Grackle nor that for Red-winged Blackbird make any suggestion as to why these species flock together in the fall, though both accounts note that they do. They’ll actually migrate, during the day, in large flocks like this (many if not most other passerines will migrate individually at night), so perhaps the flocking behaviour does provide for some safety in numbers from diurnal hunters such as hawks and falcons. Blackbirds remain in large mixed-species flocks through the winter, too, often numbering in the hundreds of thousands or more. The Birds of North America account for Red-wings notes that “Very large flocks may stretch for miles.” Needless to say, the flocks we observe up here during migration never get that large.
The flock from that previous day wasn’t foraging the way the morning group was. Instead, they perched high in the treetops, talking loudly amongst themselves. At some unseen signal they lifted off together, swirling about and re-settling in some other tall trees farther into the forest. I suspect they were staging – preparing to depart south. I’m not sure why birds stage like this, either. Are they counting heads to make sure everyone’s present before they leave? Maybe they’re waiting for the appointed hour and these were the individuals to arrive so far (“The bus leaves at five, but try to show up early to make sure you don’t get left behind”)? Everyone hanging out while they do their warm-up stretches in preparation for the long flight?
The noisy flocks are just another sign that summer’s drawn to a close. Soon, they’ll all be gone, nearly all of them for points south of the border, and we won’t see them again until March.