Bicknell's Thrush - Catharus bicknelli

Bicknell's Thrush has a partial preformative molt but no prealternate molts. Age can usually be determined reliably through examination of the primary and greater coverts, but some intermediates may become more difficult to identify by spring and should be considered M-FCF (AHY) unless multiple characteristics indicate a particular age. Sex can generally be determined only by brood patch / cloacal protuberance during the breeding season.

Bicknell's Thrush is quite similar in appearance to Gray-cheeked Thrush and should be identified with care in areas where both may occur. Bicknell's Thrush generally shows more yellow on the lower mandible and a greater contrast between the back and a rustier tail; consider also wing and tail measurements (see Pyle 1997).

Quick tips

• Look at the greater coverts - on FCF (HY/SY) birds, up to a few innermost ones (often two) are generally longer and uniform in colour, while the remainder are retained juvenile feathers and often show buffy-white shaft streaks, although these may be less evident by spring; the absence of such streaks should therefore not be used as evidence of DCB (AHY/ASY).
• Examine the short outermost primary (p10) - on FCF (HY/SY) birds it is broad, rounded, and 0-6 mm shorter than the primary coverts, while on DCB (AHY/ASY) birds it is narrow, pointed, and 4-10 mm shorter than the primary coverts.
• Consider the shape of the rectrices - they are narrow and relatively pointed on FCF (HY/SY) birds, but broad and relatively rounded on DCB (AHY/ASY) birds.

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