Voice: High whistled tseet tseet followed by short whistles.
Strictly winter visitors, American tree sparrows, can be commonly seen in old fields, grassy meadows and at bird feeders. Despite their name, American tree sparrows, are not associated with trees, instead foraging and nesting on the ground. Instead their name comes because the birds reminded them of the Eurasian tree sparrow.
Fall through spring American tree sparrows are herbivores, eating plants that primarily include sedge, ragweed, knotweed, goldenrod, and other seed bearing plants. They will on occasion eat berries, catkins, insects, insect eggs and larvae when available. In the winter they frequently scratch at exposed soil to uncover seeds that have been buried. During the summer months their main diet also includes insects such as beetles, flies, leafhoppers, wasps, moths, and caterpillars. They will also eat snails and spiders.
American tree sparrows breed in low shrubby growth along the northern Canada’s tree limit. In up to seven days females construct their coarse grass, weed stem nest on or near the ground at the base of a shrub, grass tuft or deal branch. They line their nest with fine dry grass, moss, feathers, and hair. American tree sparrows synchronize hatching and fledging. Females lay one pale bluish or greeish, with brownish spotting, egg per day until she has laid three to six eggs. Despite males visiting the nest, only females incubate the eggs over the next 11-13 days. The young hatch within hours of each other and may not hatch in the order their eggs were laid. Both parents tend to young before they leave the nest nine to 10 days after hatching. They are unable to fly and are fed by the parent for up to two more weeks.
American tree sparrows are abundant and widespread because most nesting areas are remote from human disturbance. Partners in Flight estimates the global breeding population at 20 million. In the winter range, they adjust readily to disturbed habitats, human settlement and capitalize on foraging at backyard feeders.