Saturday, February 2, 2013

Tree Sparrows


They migrate across southern Canada and winter in the colder portions of the lower 48 from Washington to Maine and south as far as Oklahoma. Contrary to their name, you're just as likely to find them in some bushes or feeding on the ground with the juncos. Their natural food is fallen weed seeds picked off the snow. If the snow grows deeper, they will cling to the taller plants while they pluck the seeds. In the winter they obtain water by eating snow.

Tree sparrows do not defend winter territories, but they do form dominance hierarchies and they sometimes spend the night as a group under the snow to escape bitter cold wind. Otherwise they individually roost in conifers or marshes.

tree sparrow at the Montezuma Audubon Center, Savannah, NY

In April they will head north to breed in the Arctic, generally above the tree line. They even nest on the ground, albeit in open, scrubby areas with alder thickets, dwarf willows, birches and stunted spruce. During the short summer, they eat primarily insects and spiders instead of seeds. For a bird that spends so much of its time on the ground, why would it be named "tree sparrow"? I have yet to find a good reason, but I often see them perched in trees or bushes. I suspect that early ornithologists first encountered this species sitting on tree branches.

Not quite as drab as some sparrow species, the American Tree Sparrow (Spizella arborea) sports a rusty cap, chestnut line behind the eye, some rufous on the shoulders and sides, an isolated dark spot on a gray breast, and a white wing bar. (At close range, you might notice part of a second wing bar.) One of this sparrow's distinctive field marks is a bicolored bill, dark on top and yellow on the lower mandible. This species' back is light brown with dark streaks, and the long, notched tail has dark-gray feathers with pale edges. Males and females are nearly identical and juveniles are similar but more streaked.

Tree sparrows are preyed on by Accipiters, kestrels, screech owls, weasels, foxes and even Red Squirrels. The average life expectancy is two to three years, but one tree sparrow was recorded as surviving 10 years and nine months.

For more information, photos, similar species and typical voice sounds, visit All About Birds. eBird provides an interactive range map of this strictly North American species (zoomable to your location).

Corrections, comments and questions are always welcome at northeastnaturalist@yahoo.com or connect through my Facebook page and photo page. There's also a community-type page for The Northeast Naturalist. Other nature and geology topics can be found on the parallel blogs Adirondack Naturalist and Heading Out.

1 comment:

mindfuldrawing.com said...

The Eurasian Tree Sparrow, Passer montanus, in is Dutch a 'Ringmus'. It is a lovely, chatty bird.