Brown Thrasher - Toxostoma rufum

Brown Thrasher has a partial preformative molt but no prealternate molts. Age can often be determined by examination of the wing and tail, although by spring characteristics can become less distinct, and some individuals may need to be considered M-FCU (AHY). Sex can be reliably determined only by brood patch / cloacal protuberance during the breeding season.

Quick tips

• Carefully examine the greater coverts - on FCF (HY/SY) birds, some to many of the innermost ones are contrastingly long, fresh, and dark, whereas on DCB (AHY/ASY) individuals they are uniformly fresh, though beware a pseudolimit with the outermost greater coverts having somewhat rustier tips.
• In fall, check the iris - on FCF (HY) birds it is grayish to pale yellow, while on DCB (AHY) birds it is yellowish-orange to orange.
• Examine the tail - on FCF (HY/SY) birds the outer feathers are somewhat more tapered and worn, especially by spring; on DCB (AHY/ASY) birds they are relatively broad, rounded, and tend to show less wear.

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