Migration Research Foundation - McGill Bird Observatory - Photo Library

McGILL BIRD OBSERVATORY

PHOTO LIBRARY

White-throated Sparrow (Zonotrichia albicollis)

Seasonal status at MBO:

JAN

FEB

MAR

APR

MAY

JUN

JUL

AUG

SEP

OCT

NOV

DEC

common

fairly common

uncommon

rare

occasional

no records

QUICK TIPS:

1) Look at the tail - uniformly narrow and pointed rectrices are indicative of HY/SY, while broad and more rounded rectrices are typical of AHY/ASY, but beware that some individuals may replace their tail early, so this is less reliable for AHY/ASY

2) Check the outer primary coverts - they are relatively narrow and pointed on HY/SY birds and relatively broad and rounded on AHY/ASY birds

3) Look at the iris in good light - it is grayish-brown in HY birds and reddish brown in AHY birds (criterion reliable only in fall)

4) Outside of the breeding season, sex of some individuals may be determined using wing chord - a length <69 mm is largely limited to females, and a length >72 mm is largely limited to males

Note that although there is considerable variation in head patterns, it appears to be generally unreliable for ageing and sexing.
Also, as is the case for many sparrows, a large percentage of intermediates cannot be reliably aged in spring.

Ageing and sexing guidelines:

Note: there are white-striped and tan-striped morphs of this species which look considerably different, but these are genetic differences, and while differences in head colouration are to some degree related to age and sex, they should not be used to classify individuals in the field.

January - July:

ASY - U Age can be difficult to assess in spring. Broad and rounded rectrices, and broad dark outer primary coverts are the best indicators of ASY.
SY - U Age can be difficult to assess in spring. Narrow and tapered rectrices, and narrow pale outer primary coverts are the best indicators of SY.

June - December:

AHY - U Reddish-brown iris, unstreaked breast, dark primary coverts, and broad rectrices.
HY - U Gray-brown iris, sometimes lightly streaked breast, relatively pale primary coverts, and narrow pointed rectrices.
JUV - U Streaked breast, limited colouration to coverts, and narrow but fresh rectrices.

Ageing and sexing details:

after-second-year unknown

Age can be difficult to assess in spring. Broad and rounded rectrices, and broad dark outer primary coverts are the best indicators of ASY. Sex can be determined reliably only by cloacal protuberance or brood patch, though extremely short (<68mm) wing chords are indicative of females, and extremely long ones (>73mm) are indicative of males.

Photo by Marie-Anne Hudson, McGill Bird Observatory, May 2007

Photo by Marcel Gahbauer, McGill Bird Observatory, May 2006

The condition of the primary coverts is often of limited usefulness by spring. In principle, the outer primary coverts of ASY White-throated Sparrows are broader and with more extensive pale edging than those of SY birds, but in practice the differences are often difficult to see.

Photo by Marcel Gahbauer, McGill Bird Observatory, May 2006

A broad and rounded tail, such as the one below, is a good indicator of an ASY White-throated Sparrow. However, this should not be used as a sole criterion of age, as sparrows are particularly liable to lose and replace their tails prematurely.

Photo by Marcel Gahbauer, McGill Bird Observatory, May 2006

RETURN TO AGE/SEX OVERVIEW

second-year unknown

Age can be difficult to assess in spring. Narrow and tapered rectrices are the best indicators of SY, while particularly pale and worn primary coverts are also useful, but only occur occasionally. Sex can be determined reliably only by cloacal protuberance or brood patch, though extremely short (<68mm) wing chords are indicative of females, and extremely long ones (>73mm) are indicative of males. The second photo below is of a tan morph bird.

Photo by Marcel Gahbauer, McGill Bird Observatory, April 2006

Photo by Marie-Anne Hudson, McGill Bird Observatory, June 2006

The condition of the primary coverts is often of limited usefulness by spring. In principle, the outer primary coverts of SY White-throated Sparrows are narrower and paler than those of ASY birds, and with less pale edging, but in practice the differences are often difficult to see.

Photo by Marcel Gahbauer, McGill Bird Observatory, April 2006

A narrow, tapered, and worn tail, as in the photos below, is a reliable indicator of an SY White-throated Sparrow.

Photo by Marcel Gahbauer, McGill Bird Observatory, April 2006

Photo by Marie-Anne Hudson, McGill Bird Observatory, June 2006

RETURN TO AGE/SEX OVERVIEW

after-hatch-year unknown

Iris reddish-brown; breast lacking streaks. While eye colour is quite reliable, it can be difficult to assess accurately under some light conditions, and so both wing and tail should be examined too.