Because of their remote and widespread range, little is known about their breeding ecology. Tree Sparrows are winter residents in the Chain of Lakes area, where they typically arrive in early November and depart by early April. American Tree Sparrows winter across the United States, stretching from the Pacific Northwest east to the Eastern Seaboard and south to the Carolinas and northern Georgia.
A small sparrow with a bicolored yellow and black bill, American Tree Sparrows can be distinguished from other sparrows by their rufous coloration, unstreaked breast, and rusty cap. They have two white stripes on the wings, a slim rufous eyeline, and a streaked back. Both males and females look alike. Tree Sparrows’ song is a high-pitched, tinkling warble, often sung in late winter.
American Tree Sparrows will readily come to feeding stations to feed on seed on the ground. They feed on a wide variety of weed seeds, berries, and insects, hopping and scratching at the ground to expose seeds or insect larvae. Many Tree Sparrows will also feed on tree seedpods, particularly catkins, or berries directly from the tree. American Tree Sparrows primarily feed on weed seeds during the winter, however; an Iowa study estimated that Tree Sparrows consume 875 tons of weed seeds in the state each winter.
Although they have small territories on their breeding grounds, Tree Sparrows are typically found in flocks during the winter. Individuals forage closer together in colder temperatures, and they may roost communally under the snow to conserve warmth during cold snaps. If they have enough food, Tree Sparrows can readily survive subzero temperatures, and can thus thrive in open, brushy habitats. A flock of twenty or thirty Tree Sparrows, softly tinkling among the silent winter landscape of an overgrown field, is a bright sight on a gray day.
Click Here for Telling Chipping from American Tree Sparrows
Click Here for a Blog Post About a Flock of Winter Tree Sparrows
Click Here for information from the Boreal Songbird Initiative
Click Here for information from Birds of North America