Lincoln’s Sparrow

The Lincoln’s Sparrow is often considered among the more elusive of North American birds often overlooked in migration because of its skulking habits and similarity to the Song Sparrow. It has a sweet, bubbling song that suggests a House Wren or Purple Finch. It breeds in south Alaska, BC, across Canada to the Atlantic, in small areas of northern and western USA. It winters in coastal and Baja California, southwestern US, Mexico and northern Central America.

Adult Male (spring/summer)

Median strip gray, crown rusty brown often peaked, broad gray supercilium, dark brown eye-line, eye-ring and auricular buffy, dark brown subauricular stripe and buffy submoustachial stripe. Throat is white and finely streaked brown. Crisp dark brown streaks contrast with buffy breast and flanks, belly white and buffy brown streaked undertail coverts. Nape, back, wings and tail brownish gray with fine dark streaks.

Adult Female (spring/summer)
Sexually monomorphic.

Juvenile

Very similar to adults but crown brown or grayish brown streaked, and supercilium brownish. Edges of coverts and tertials may be somewhat rusty.

General:

Medium sized, delicate sparrow. Length: 13-15cm. Wing: 19cm. Weight: 17-19grams.

Behaviour:

Secretive, this sparrow skulks through underbrush. Singing males are inconspicuous as they sing from dense thickets advertising their 1-acre territory. They forage in very small numbers or by themselves and spend most of their time on the ground walking and hopping as they search for insects, grain, and seeds.

Habitat:

Breeds in boreal regions and exhibits a distinct preference for dense shrub covers. It occupies boggy areas with stunted tamarack, black spruce and low willows, alders, riparian thickets and scrubby areas.

Information:

In migration and winter the Lincoln Sparrow occurs in dense low cover and rarely far from cover and do not seem to flock. They are generally said to be skulkers, but respond well to ‘pishing’ and are not hard to see. Lincoln Sparrows often raise the crown feathers to form a short crest. This together with the eye-ring and the tail slightly cocked create a curious ‘wide-awake’ look. The nest is placed on the ground in a well concealed shallow depression. The nest is a fragile cup of sedges and grasses and dead leaves, lined with finer grasses and sometimes hair. The clutch is 3-6 greenish white, spotted with reddish brown eggs.

Similar species:

Song Sparrow, Swamp Sparrow.

Conservation Status:

Listed as Least Concern. Populations appear to be stable.

Capture Rates

Not a breeder at Colony Farm, Lincoln’s Sparrow is seen passing through in great numbers during Spring and Fall Migration. This is indicated by the peak of capture rates in April/May and then again in August-October. The park seems to be especially important for these sparrows during fall migration as seen by the huge spike in captures during September.

Molt Summary

PF: HY partial; PB: AHY complete; PA limited-partial
Preformative molt usually includes all med and gr covs, occasionally 1 – 2 terts, and sometimes 1 -2 central rects (r1)
The PA’s include no gr covs or rects but, occasionally, 1 – 2 terts

LISP are among the Emberizid family which often show an alula covert (A1) molt limit (macro photo below). The differences between this tiny feather and the adjacent main alula feather (A2) can be very subtle but here there is a clear A1 limit – note the darker rachis of the molted A1 feather (red arrow).

This hatch year (HY) bird in September has replaced lesser, median, greater coverts, carpal covert and the two inner most tertials (S8 & 9) – molt limits are indicated between the replaced outer greater covert and retained inner primary covert; between the replaced greater alula covert (A1) and the main alula feather A2 and between S8 and S7 (red arrows). When tertials are replaced like this central retrices are also sometimes replaced.

Replacement of tertials is variable depending on subspecies. The gracilis subspecies almost always replace the two inner tertials and central retrices in the preformative molt. The photo below shows the rectrices of the HY bird in September above with the bird’s right hand side innermost rectrix (R1) still growing (red arrows). Notice the dark centres to these two feathers and glossy, black rachises.

This HY bird in September has also replaced central rectrices – notice again the dark centres to these two feathers and darker rachises.

This SY bird in May has replaced all lesser, median and greater coverts in its preformative molt following the breeding season last year; the molt limit indicated by the red arrow between replaced outer GC and retained inner PC. The blue arrow points to the inner tertial replaced as part of its first prealternate molt this spring.

Notice also the very thin, tapered primary coverts with little or no pale brown edging. Thus there are 3 generations of feathers: retained juvenal primaries, secondaries, primary coverts and main alula feathers (A2 & A3), formative lesser, median, greater coverts, carpal covert and greater alula covert (A1); and first alternate inner most tertial (S9).

Compare the primary coverts of these two birds – SY on the left and ASY on the right. Notice the thin, tapered and worn PC’s of the SY bird with little or no pale brown edging versus the broad, truncate PC’s of the ASY bird with relatively distinct and broad pale brown edging.

This AHY bird in August is in the midst of its definitive, complete prebasic molt which includes all body and flight feathers starting with the lesser and median coverts, then tertials and innermost primaries. Primary replacement proceeds distally towards the outermost primary (P9) with primary coverts molting withy the corresponding primary. The greater coverts molt shortly after the start of the primaries (which is the stage at which this photo was taken), the carpal covert being replaced when the GC’s complete. The alula covert (A1) is molted with the median coverts, the main alula feathers are molted during the molt of the primaries and are among the last to be replaced. After the tertials, the remainder of the secondaries are molted beginning with the outermost and proceeding proximally towards the birds body with S6 normally the last flight feather replaced.

This ASY bird in April is a prime example of what definitive adult plumage looks like in spring. Notice the broad, truncate and dusky brown outer primary coverts with relatively distinct and broad, pale brown edging not contrasting markedly in colour or wear with the greater coverts. The blue arrow indicates the two replaced innermost tertials (S8 & S9) replaced as part of the bird’s adult alternate molt in the late winter/early spring. Thus two generations of feathers are present: adult basic (all feathers except the two innermost tertials) and adult alternate (the two innermost tertials).