American Tree Sparrow

Spizella arborea

Introduction

The American Tree Sparrow is a winter resident in a large area of central North America and is seen in winter flocks and at many backyard feeders. Its rufous cap and gray breast with a central black spot are diagnostic. Its breeding range is Alaska, northern BC, northern Yukon, Northwest Territories, northern Saskatchewan, northern Manitoba, northern Ontario, north and central Quebec and Labrador.

Identification

Adult Male (spring/summer)

Rusty cap, often with a grayish median crown stripe and gray supercilium; eyeline rusty; lores gray. The back is rusty brown with dark streaks. The rump and wings are brown with rusty brown coverts and two distinct wing-bars. The chin, throat and upper breast are gray with a distinct black spot in the central breast. The lower flanks and lower belly fade into warm rusty beige. The upper mandible is dark while the lower mandible is yellow with a dusky tip. Legs are brown.

Adult Female (spring/summer)

Slightly smaller than male. Similar in colouration.

Juvenile

Similar to adults but with a streaked brown cap, nape and side of neck. Underparts, except for the lower belly are heavily streaked with blackish brown, often with a distinct breast spot.

General Information

General:

Medium size sparrow.
Length: 13-15cm. Wing: 60-82mm. Weight: 12.6-27.7 grams.

Behaviour:

In summer males sing persistently to proclaim possession of territory.  In the winter they are generally found in loose flocks or small groups and seen at feeders. Taking seeds, berries and insects for food they can be seen foraging among weeds and grasses and along branches and twigs.  When flushed from the ground they commonly fly up into a small nearby tree where they can be easily observed. 

Habitat:

Breeds usually near treeline in open scrubby areas in willow, birch and alder thickets, and in stunted spruce, open tundra with scattered shrubs, often near lakes and bogs. During migration and winter they can be seen in fields, marsh hedgerows, gardens, open forests, residential neighbourhoods and feeders.

Information:

The name American Tree Sparrow is somewhat of a misnomer as most individuals breed in remote northern areas, often north of the treeline. The name was given to this bird by early European settlers for the superficial resemblance it has with the Eurasian Tree Sparrow (Passer montanus).
The nest, built by the female, is a neatly woven cup of dead sedges or grasses, weed stems, rootlets lined with finer grasses, feathers or hairs. Three to six white to pale greenish eggs heavily spotted with reddish brown are laid.

Similar species:

Field sparrow.

Conservation Status:

Listed as Least Concern.

Maps & Statistics

Capture Rates

American Tree Sparrow breed in the far north and migrate to central North America in the winter, in most cases south of the border throughout the United States. Therefore, American Tree Sparrow is a rare visitor to Colony Farm as is reflected by the capture of only a few individuals in April and zero capture rate for the remainder of the year.

Ageing and Sexing (Band Size: 0, 1)

Molt Summary:

PF: HY partial, PB: AHY complete; PA limited.
1st PB usually includes all med and gr covs, 1-3 tertials and sometimes 1-2 central rects. PA limited to body feathers although 1-2 terts and/or central rects rarely can be replaced.

HY/SY

SEPTEMBER - AUGUST

The preformative molt in HY ATSP includes all median and greater coverts and normally 1-3 tertials.

AHY/ASY

SEPTEMBER - AUGUST

This adult after second year (ASY) in spring is showing a uniformly adult wing with no discernible molt limits. The more exposed feathers of the wing can appear slightly more worn than the less exposed feathers, covered by other feathers when the wing is closed, but that amount of wear is clinal rather than abrupt as it would appear in a HY/SY bird. The tertials and middle secondaries (s4-s6) are all uniformly adult, edged buffy whitish and the primary coverts appear fairly broad and fresh with relatively distinct, pale rufous edging and don’t contast in wear with the adjacent greater coverts.

The slight colour contrast between GC’s 6 and 7 with broader edging to the inner GC’s simulates a molt limit but is a natural colour contrast (pseudolimit) verified by the equal amount of wear to the tips of all the GC’s.

ATSP can rarely replace tertials in the PA molt but again the amount of wear to these 3 feathers is consistent with the GC’s having been replaced following the breeding season last year as part of this birds definitive adult prebasic molt.

Tail shape can be helpful in ageing being generally more tapered in hatch year birds and more truncate in adults although determining the age of birds by tail feather shape alone is generally not very reliable because of individual variation and the possibility of accidental loss and replacement (i.e., adventitious molt). Tail shape should always therefore be used with caution and only in conjunction with other ageing criteria (e.g. molt limits).