The American Tree Sparrow's summer range is Alaska and northern Canada, but it winters in southern Canada to central United States, where it is found in open fields, woodland edges, marshes and suburban areas.
In its winter area in southern Canada and U.S., its diet is almost entirely seeds of grasses, weedss and other plants; also a few insects and berries.
Its summer diet in Alaska and northern Canada is almost all insects.
In its summer nesting area in Alaska and northern Canada, the nest site is on or near the ground in grass clumps beneath shrubs. Nest, built by the female, is an open cup of twigs, grasses and moss, lined with fine grass and feathers.
4-6, pale bluish or greenish color. Incubation is by the female, 11-13 days.
Both parents feed the nestlings. Young leave the nest at 8-10 days, when feathers are not fully grown. Parents may lure them away from the nest by offering food. Young are able to fly at about 14-15 days after hatching, and parents continue to feed them for about 2 more weeks. One brood per season.