In summer, American Tree Sparrows breed near the northern treeline, where straggling thickets of alder, willow, birch, and spruce give way to open tundra. Though some American Tree Sparrows nest in open tundra, most territories include at least a few small trees that the males can sing from, along with a source of water. During spring and fall migrations, they'll search out weedy fields, marshes, hedgerows, and open forests for foraging between nights of flying. They winter in similar habitats in their southern range, adding gardens and backyards with feeders in settled areas. Back to top
American Tree Sparrows eat seeds, berries, and insects, but the relative proportions of those foods change radically from winter to summer months. From fall through spring, they're almost exclusively vegetarian, eating grass, sedge, ragweed, knotweed, goldenrod, and other seeds, as well as occasional berries, catkins, insects, insect eggs, and larvae. In settled areas, they happily eat small seeds from feeders—including millet scattered on the ground. In summer, after their migration north, they begin eating a wider and wider variety of insects until, during June and July they eat almost exclusively insects such as beetles, flies, leafhoppers, wasps, moths, and caterpillars, as well as spiders and snails. These protein-rich foods are particularly important for the growing chicks. Once the chicks are gone, their diet begins reverting to its winter pattern. They may augment their summer food with seeds from alder, spruce, blueberries, and cranberries. Back to top
American Tree Sparrows nest on or near the ground, often in a tussock of grass at the base of a shrub, occasionally as high as about 4 feet on a limb of a willow or spruce. In open tundra with no trees in sight, the nest may sit on a mossy hummock.
Open cup of moss, grasses, shreds of bark and twigs, lined with fine grass and feathers (usually from a ptarmigan). Placed on or near ground, often in tussock of grass at base of shrub.
|Clutch Size:||4-6 eggs|
|Egg Description:||Pale blue with reddish speckling.|
|Condition at Hatching:||Helpless with sparse tufts of brownish gray down.|
In winter, American Tree Sparrows often forage industriously in small flocks. They scratch the ground for dried seeds, and hop up at bent-over weeds or along low branches gathering catkins or berries. Inventive in their foraging, they've been seen beating grass seedheads sticking up out of the snow with their wings to release seeds they can pluck from the ground. These hardy birds often continue foraging undaunted as winter blizzards roll in. Individuals may take solitary perches on low branches or atop stalks like goldenrod. In their summer range, they search out insects from weeds and bushes, occasionally snatching moths or mosquitoes from the air as well. As their spring migration progresses, flocks dissolve and American Tree Sparrows pair up. Females spend much of their time on the nest they build and rarely venture outside the male's territory. Males roost nearby, visiting the nest frequently. Pairings don't outlast breeding season. Back to top
Partners in Flight estimates the global breeding population of American Tree Sparrow at 26 million and rates them 10 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. However, American Tree Sparrow are included in the list of Common Birds in Steep Decline for species that are still too numerous or widely distributed to warrant Watch-List status but have been experiencing troubling long-term declines. American Tree Sparrows breed across 250 million acres of northern Canada and Alaska, beyond the range of usable timber or arable land, where they're generally unaffected by humans. Local populations can be at risk from development, as a study that found American Tree Sparrows with high levels of arsenic compounds in a gold-mining region in the Northwest Territories shows. But common predators like hawks and owls don't threaten overall numbers. During the winter, American Tree Sparrows thrive all across southern Canada and the northern United States. They adjust easily to disturbed habitats and human settlements, flocking around backyard feeders.Back to top
Lutmerding, J. A. and A. S. Love. (2020). Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.
Naugler, Christopher T., Peter Pyle and Michael A. Patten. (2017). American Tree Sparrow (Spizelloides arborea), version 2.1. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.
Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.
Rosenberg, K. V., J. A. Kennedy, R. Dettmers, R. P. Ford, D. Reynolds, J. D. Alexander, C. J. Beardmore, P. J. Blancher, R. E. Bogart, G. S. Butcher, A. F. Camfield, A. Couturier, D. W. Demarest, W. E. Easton, J. J. Giocomo, R. H. Keller, A. E. Mini, A. O. Panjabi, D. N. Pashley, T. D. Rich, J. M Ruth, H. Stabins, J. Stanton, and T. Will (2016). Partners in Flight Landbird Conservation Plan: 2016 Revision of Canada and Continental United States. Partners in Flight Science Committee.
Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.