0 the american tree sparrow (spizella arborea), formerly known as the winter sparrow , is a medium-sized sparrow .
1 adults have a rusty cap and grey underparts with a small dark spot on the breast .
2  they have a rusty back with lighter stripes , brown wings with white bars and a slim tail .
3  their face is grey with a rusty line through the eye .
4  their flanks are splashed with light brown .
5  they are similar in appearance to the chipping sparrow .
6 their breeding habitat is tundra or the northern limits of the boreal forest in alaska and northern canada .
7  they nest on the ground .
8 these birds migrate to the united states or southern canada to spend the winter .
9  usually , chipping sparrows are moving south around the same time as these birds arrive .
10 these birds forage on the ground or in low bushes , often in flocks when not nesting .
11  they mainly eat seeds and insects , some berries .
12  they are commonly seen near feeders with dark-eyed juncos .
13 this bird's song is a sweet high warble descending in pitch and becoming buzzy near the finish .
