American Tree Sparrow

The American Tree Sparrow is a plump, round-headed sparrow with a rusty-red cap, a rusty stripe extending back from the eye, and a plain gray face and unstreaked breast marked by a single dark central spot. The bill is distinctively bicolored, dark on the upper mandible and yellow on the lower.

Despite the name, this species has little to do with trees; it breeds far north on the Arctic and subarctic tundra and is encountered by most North American birdwatchers only as a hardy winter visitor to weedy fields and feeders, often in the coldest months of the year.

Key field marks

• Rusty cap and rusty eye-stripe on a plain gray face
• Bicolored bill: dark above, yellow below
• Single dark spot in the center of an otherwise unstreaked, pale gray breast
• Rusty patch on the sides/shoulder and two white wingbars

Similar species

• Chipping Sparrow also has a rusty cap but shows a black eyeline, an all-dark bill, and lacks the central breast spot; ranges rarely overlap since Chipping Sparrows leave before Tree Sparrows arrive for winter.
• Field Sparrow has an all-pink bill and a plainer face without the rusty eye-stripe.

American Tree Sparrows breed in the low shrub and stunted tree zone at the edge of the Arctic tundra across northern Canada and Alaska. For the rest of the year they migrate south to spend the winter across the northern and central United States and southern Canada, in weedy fields, brushy hedgerows, marsh edges, and backyard feeders.

The species is highly cold-hardy, often remaining active and foraging even in harsh winter weather, and is one of the latest sparrows to depart northward in spring and among the last winter sparrows to be seen as snow melts.

In winter, American Tree Sparrows forage in flocks on the ground and in low weeds and shrubs, often scratching at snow to reach buried seeds, and readily visit feeding stations offering millet or mixed seed. They are generally tolerant of cold and can be seen actively foraging even in sub-freezing temperatures.

The call is a soft, musical "tseet" or "teedle-eet," and the song, mostly heard on the breeding grounds, is a sweet, variable warble. On the tundra breeding grounds, nests are built low in shrubs or on the ground, well hidden by vegetation, with typical clutches of four to six eggs; diet on the breeding grounds shifts toward insects to feed growing chicks.