White-crowned Sparrow

The White-crowned Sparrow is one of the best-studied songbirds of North America. It is an elegant, abundant bird and has a wide distribution. And, it is conspicuous during most stages of its annual life cycle. The White-crowned sparrow breeds in northern Canada, Alaska, and BC, western Alberta and in some western states of the US. It winters in southwestern BC, much of the lower 48 states of the US and northern Mexico.

Adult Male (spring/summer)

Median crown stripe bright white; lateral crown stripe black; supraloral gray; supercilium white; black eye-line; auricular gray; subauricular stripe dark gray; submoustachial stripe gray; malar stripe dark gray and chin, throat lighter gray. Orange-pink bill. Breast unmarked gray-buff; belly lighter gray; flanks dull brown and undertail coverts dull white. Nape gray; back brown with buff stripes and rump and uppertail coverts pale gray-brown. Tail dull brown. Wings black with rufous feather edging and two white wingbars. Feet dull flesh colour.

Adult Female (spring/summer)
Same as male.

Juvenile

Fairly well defined dark crown and head stripes. Breast, belly and flanks streaked dark brown.

Gambelii

Averages larger but bill relatively small. Upperparts medium-dark grayish brown and reddish; upper lores pale grayish brown (HY) to white (AHY), not contrasting with the supercilium; auriculars of HY moderately distinct and grayish brown; bend of the wing pale grayish; sometimes tinged yellow; underwing covs silvery-gray; breast pale, bright brownish (HY) to gray (AHY), bill pinkish to tawny.

Wing Chord:       Tail
M: 74-84               67-76
F: 69-79                64-73

This classic gambelii has these characters:

– orange bill

– darker pure gray neck & breast with brownish flanks

– contrasting back pattern of deep reddish centers and pale gray edges

– rich chestnut edges to inner greater coverts & tertials

– long primary projection

Pugetensis:

Small, bill small; crown of SY (Mar-Jul) black and white; with little or no brown; upperparts medium-dull brown and olive; upper lores pale grayish brown (HY) or white (AHY), not contrasting with the supercilium; auricular of HY indistinct and brownish-gray; bend of the wing yellowish and brown; underwing covs brown with a yellowish wash; breast medium-dull brownish (HY) to grayish brown (AHY) bill yellowish to orange.

Wing Chord:      Tail:

M: 67-75              64-74      
F: 64-72               62-70

This classic pugetensis has these characters:

– yellow bill

– paler gray neck/breast contrasts with brownish flanks

– contrasting back pattern of blackish centers and tan edges

– dull rusty-brown edges to inner greater coverts & tertials

– long primary projection

General:

Large, long-tailed, long-necked sparrow. Length: 15-16cm. Wing: 21-24cm. Weight: 25-28grams.

Behaviour:

The White-crowned Sparrow spends much time low in open areas and at the edges of brushy habitat, in hedgerows and shrubby habitats. There they hop and forage for seeds of weeds and grasses and insects. Males on breeding territory can be seen and heard constantly singing perched atop a shrub or tree.

Habitat:

Open habitats with hedgerows, shrubs and thickets. Also found in urban areas where ever there are hedges, shrubs, parks and back yards which are adjacent to open areas.

Information:

During the winter, diet consists manly of buds, grass, fruits, and invertebrates when available. The white-crowned sparrow produces and open cup nest, which is generally placed from ground level to 1.5m in shrubs, but can be placed up to 2.5m off the ground in tall shrubs or low tree branches. Clutch size generally ranges between 3-7 greenish, greenish-blue spotted with reddish brown eggs. In some areas, white-crowned sparrows can produce multiple successful nests in a single breeding season. The oldest recorded white-crowned Sparrow was 13 years 4 months old. White crown males can sometimes be heard singing at nighttime on the breeding grounds.

Similar species:

Golden-crowned Sparrow, White-throated Sparrow, House Sparrow, Lark Sparrow.

Conservation Status:

Listed as Least Concern. Numbers are numerous and widespread.

A potential year round resident of southern British Columbia, capture rates of White-crowned Sparrow at Colony Farm, where habitat is ideal for this species, can be seen throughout most of the year. Rates peak in September during juvenile dispersal and when those migrant individuals are preparing for their short journey south.

Molt Summary:

PF: HY partial; PB: AHY complete; PA partial

Preformative molt usually includes all med and gr covs, sometimes 1 – 3 terts, and sometimes 1 -3 central rects (r1)

PAs include 0 – 8 inner gr covs, usually 1 – 3 terts, and often 1 – 2 central rects (r1)

PAs are similar between the two age groups but differ in extent by geography – in pugetensis fewer feathers are replaced on average: Typically, 0 – 3 gr covs and terts, and only occasionally the central rects (r1)

Replacement of head feathers is also more restricted in some subspecies to others.

Note: Zonotrichia sparrows have strong colour contrasts (or pseudolimits) within the greater coverts which simulate molt limits but are in fact not true molt limits. These pseudolimits are present in both HY/SY and AHY/ASY birds. Examine the extent of wear to the feather tips to see if it is a true molt limit.

The wing below shows a hatching year (HY) White-crowned Sparrow (WCSP) in September which had completed its preformative molt and replaced all lesser, median, greater coverts and carpal covert but nothing else – no tertials or central retrices – the molt limit shown with the red arrow between the replaced outer greater covert and retained inner primary covert. Notice the contrast between the replaced greater alula covert (A1) and lower main alula feather (A2) also indicated with a red arrow. White-crowned Sparrows are among the Emberizid family which often show this key alula covert (A1) molt limit.

Notice also the ‘pseudolimit’ mentioned above (green arrow) within the greater coverts, a natural colour contrast simulating a molt limit when in fact all greater coverts have been replaced here.

This HY also in September has replaced lesser, median, greater coverts and carpal covert and the two innermost tertials (large red arrows); the molt limit between the outer greater covert and inner primary covert. Again notice the more rufous edged inner greater coverts and single retained median covert (small red arrow).

The significance of the greater alula covert A1 (red arrow) can again be seen in this photo of a HY in August in the midst of its partial preformative molt with A1 in sheath – a molt limit in the making! The sequence of events in a partial preformative molt can be clearly seen here as this bird replaces lesser, median, greater coverts, the greater alula covert (A1) and two innermost tertials but not the lower two alula feathers, carpal covert, primaries, secondaries or primary coverts which are all retained juvenal feathers.

Another HY in August undergoing its preformative molt with feathers still in sheath. This bird is replacing lesser, median and greater coverts but NOT the tertials which commence when about half of the greater coverts complete in a partial preformative molt. Therefore, the carpal covert, lower two main alula feathers, primary coverts, primaries, secondaries and tertials are all retained juvenal feathers. The molt limit is again between the outer greater covert (in sheath) and inner primary covert and greater alula covert (A1) in sheath and lower alula feather (A2) shown with red arrows.

Tail shape can also be helpful 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).

The tail of this HY bird in September is showing very narrow, tapered and abraded outer rectrices.

Although both SYs and ASY can show contrasting greater coverts, tertials and retrices and both show the pseudolimits mentioned above, SYs like this bird in May often retain a few brown juvenal feathers in the hindcrown as in the photo below and can reliably be aged SY.

This SY in May is showing 3 distinct generations of feathers having replaced lesser, median, greater coverts and carpal covert (red arrows) in its preformative molt following the breeding season last year and inner greater coverts and tertials (blue arrows) in its 1st prealternate molt during the later winter /early spring.
Notice the subtle contrast between the replaced greater alula covert (A1) and lower main alula feathers and narrow, tapered and relatively abraded outer primary coverts.

Finally, again notice the colour contrast (pseudolimit) within the inner greater coverts.

The tail of the SY bird above is again showing tapered and relatively abraded outer rectrices. The central rectrices R1 (red arrows) have been replaced as part of this birds first prealternate molt; notice the difference in shape of these two feathers with a corner to the inner web, the fresh versus worn tips and glossy blackish rachises versus the paler brownish rachises of the retained juvenal feathers.

The tail of the SY bird above is again showing tapered and relatively abraded outer rectrices. The central rectrices R1 (red arrows) have been replaced as part of this birds first prealternate molt; notice the difference in shape of these two feathers with a corner to the inner web, the fresh versus worn tips and glossy blackish rachises versus the paler brownish rachises of the retained juvenal feathers.

However, the tail of the same bird looks definitively juvenal with very thin, tapered rectrices showing extreme wear to the tips. Retrices R2-R4 on the right side are replaced feathers presumably having been adventitiously lost (i.e. outside the normal molt cycle) sometime during the winter months. Given the two contrasts of an adult looking wing and juvenal tail this bird must be aged AHY.

The difference between a true molt limit and pseudolimit can be determined by examining the extent of wear to the feather tips as can be seen in the super-macro photo below of the inner greater coverts of an SY in May. The inner GCs have been replaced in this birds 1st prealternate molt and are not only darker and glossier than the outer GCs but are fresher with less wear to the tips.

This after hatch year (AHY) WCSP is in the final stages of its definitive adult prebasic molt with P9 still in sheath and final inner secondaries growing in. S6 indicated with a red arrow is usually the last flight feather replaced in complete adult prebasic molts in passerines.

The pseudolimits mentioned throughout this species account are present in both HY/SY and AHY/ASY birds as can be seen in the AHY below which has replaced all of its greater coverts in its definitive adult prebasic molt. The blue arrow points to an inner GC which appears darker and glossier than the adjacent outer GCs but which is a colour contrast and not a molt limit.

The tail of the AHY bird above shows the fresh and truncate outer rectrices diagnostic of adult birds. Notice the shape of these feathers with a corner to the inner web.

The wing of this ASY in May shows only two generations of feathers (i.e. adult basic and adult alternate), the bird having replaced all body and flight feathers in its definitive adult prebasic molt following the breeding season last year and inner greater coverts and innermost tertials in its adult prealternate molt in the late winter / early spring.

Notice the consistency between the feather groups, the uniformly adult primaries and secondaries with very little wear and dark, glossy alula feathers and primary coverts and compare to the HY/SY birds above.

The tail of the ASY above is showing relatively fresh, glossy and truncate rectrices with little wear to the tips. Notice the corner to the inner web of R4 (red arrow).