McGILL BIRD OBSERVATORY |
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NOTE:
This species account has been moved to Piranga to allow for improved comparison
among examples.
Ageing and sexing guidelines: Note: there are
white-striped and tan-striped morphs of this species which look
considerably different; while differences
Ageing and sexing details: Age can be difficult to assess in spring. Broad and rounded rectrices in combination with uniformly dark wings are the best indicators of ASY.
The wing is usually the most reliable clue to age in spring. ASY birds lack a molt limit, and have a dark brown wing relatively uniform in colour and wear, though note that in all ages there are pseudolimits between the darker tertials and adjacent secondaries, as well as between the greater coverts and primary coverts.
ASY birds have relatively broad and rounded rectrices. However, this should not be used as a sole criterion of age, as White-throated Sparrows seem particularly liable to lose and replace their tails prematurely.
Age can be difficult to assess in spring. Narrow, tapered, and worn rectrices in combination with a molt limit on the wing are the best indicators of SY
The condition of the wing is typically the best clue to age in spring, but there are many intermediates where the presence or absence of a molt limit cannot be reliably determined.
A narrow, tapered, and worn tail is a fairly reliable indicator of an SY White-throated Sparrow.
After-hatch-year birds have a reddish-brown iris and a 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.
Primary coverts are broad and rounded, and fairly similar in colour to the adjacent greater coverts.
The rectrices of AHY White-throated Sparrows are broad and fairly rounded.
HY birds have a more grayish iris, and may retain traces of juvenile streaking on the breast. While eye colour is quite reliable in fall, it can be difficult to assess accurately under some light conditions, and so both wing and tail should be examined too.
A subtle molt limit may be visible in fall, with the replaced greater coverts contrasting with the somewhat paler retained juvenile feathers of the primary coverts, primaries, and secondaries.
HY White-throated Sparrows have relatively narrow and pointed rectrices.
Juvenile White-throated Sparrows are most easily recognized by the indistinct streaking across the upper breast. Note that in this plumage, White-throated Sparrows may be easily confused with Song Sparrows - White-throats average slightly larger, but the facial patterns should be examined carefully to ensure correct identification.
Body plumage alone is usually enough to recognize juveniles, but the very small pale tips on the juvenile greater coverts are another useful character.
The rectrices of juveniles are relatively narrow, though usually in fairly good condition because they are fresh. Distinct growth bars are often visible.
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© 2002- The Migration Research Foundation Inc. |