Birds of a feather

I stepped out of our house on a bright afternoon to go for a short bird walk, but found a silent forest besides the wind and crunch of brittle leaves. I had gone a few feet into our spruce stand when a large bird opened its wings and took flight. In complete silence it disappeared through the trees.

I'm guessing the bird was an owl, which would be one explanation for why it wasn't hunting in the middle of the day. Owl feathers break up turbulence in a way that makes their flight silent not only to our ears, but to those of their prey. But I may have been too far away to hear its flight even if it was a hawk.

As soon as the raptor was gone, the forest came alive. A brown creeper worked its curved beak under tree bark. A white-breasted nuthatch muttered "yank, yank" as it wandered head first down a trunk. The tableau was completed by the ubiquitous black-capped chickadees that pecked at spruce cones and searched for insects along twigs.

For many birds, the nuclear family is only important during the breeding season, if at all (Males of some species take no part in child-rearing, and female nest parasites like brown-headed cowbirds are done with their eggs after finding a nest to lay them in). Even birds that nest colonially generally exclude others from the immediate vicinity of their nest. Many birds defend a territory for food resources. This allows them to stay closer to their nest while foraging, since conspecifics (individuals of the same species) aren't depleting the food. Once the young leave the nest, there's less need to stay in one place. Who can even try, with the fledglings wandering blithely unaware of adult territorial boundaries? As migration begins, and winter threatens, flocks provide a multitude of eyes on the lookout for food and predators.

I drove past a cornfield the other day as a flock of common grackles came down like snow to feed on the waste grain. Nowadays cedar waxwings decorate the trees at my banding friends' house, coming to eat everything from buckthorn berries to tiny red crabapples. In the forest, it's hard to go very far before encountering chickadees chipping.

Finding chickadees is a good way to bird, since they often form the core group of mixed species foraging flocks. Warblers hang out with them during migration. Titmice, nuthatches and woodpeckers are common participants all through the winter. Even golden-crowned kinglets, which frequently migrate through but occasionally winter in this area, may join up.

These many forest species which join mixed foraging flocks understand chickadee alarm calls. The calls can rally nearby birds to mob predators, such as the raptor I saw. Some birders imitate them to draw birds into view. I don't do them myself, and not just because I'm not very good at imitating bird sounds. It seems a shame to raise a bird's anxiety level for nothing. With a real predator, mobbing not only takes energy, but there is the risk that the predator may turn the tables. Sometimes with a large predator which may not eat all that many chickadees to begin with, staying silent is the better choice.