White-throated Sparrow - Zonotrichia albicollis

White-throated Sparrow has a partial preformative molt, and limited prealternate molts that are largely restricted to feathers on the head. This species can be difficult to age, as differences in plumage can be subtle, and especially by spring, some individuals appear sufficiently intermediate that they should be considered M-FCU (AHY). Sex can generally be determined only by brood patch / cloacal protuberance during the breeding season, or by particularly short or long wing chords (<67 mm = female, >74 mm = male).

There are white-striped and tan-striped morphs of this species which look considerably different; although differences in head colouration are to some degree related to age and sex, they mostly overlap too much to be of use. Also beware that juveniles can appear quite similar to Song Sparrows, but usually have a larger wing chord and greater weight.

Quick tips

• Look at the tail - uniformly narrow and pointed rectrices are indicative of FCF/FCU (HY/SY), while broad and more rounded rectrices are typical of DCB/DCU (AHY/ASY).
• In fall, examine the iris in good light - it is grayish-brown in FCF (HY) birds, compared to brown (sometimes with a slight reddish tinge) in DCB (AHY) birds.
• Check the wing for molt limits - FCF/FCA (HY/SY) birds should show a contrast between darker/fresher greater coverts and the paler block of primary coverts, primaries, and secondaries, but this tends to be more apparent in spring and even then can sometimes be too subtle to distinguish from the pseudolimit typical of DCB/DCA (AHY/ASY) birds.

Species account prepared by McGill Bird Observatory (2016). Last updated by Marcel Gahbauer (Mar 2022)