American Robin has a partial preformative molt but no prealternate molts. Although a common species, American Robin can be challenging to age and sex due to a high degree of individual variability. Although extremes are readily identifiable, many individuals are not reliably sexed by plumage, and by spring ageing can also become particularly challenging and should be done only if key characteristics are distinct and consistent.
- Look at the greater coverts - on FCF (HY/SY) birds, some to most of the innermost ones are generally longer, 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), and beware also the potential for pseudolimits among the greater coverts in older birds.
- Examine the tail - FCF (HY/SY) birds typically have dull and relatively narrow rectrices, while DCB (AHY/ASY) birds have darker and broader rectrices; note that the extent of white on the outer rectrices does not seem to be a reliable predictor of age or sex.
- Consider the breast - it is mostly to entirely dark orange on DCB (AHY/ASY) males, orange with variable amounts of gray mottling on FCF (HY/SY) males and DCB (AHY/ASY) females, and pale orange with moderate to considerable gray mottling on FCF (HY/SY) females; note also that FCJ/FCF (HY) birds of either sex may retain dark breast spots well into fall.
- Look at the crown - it is largely to completely blackish on DCB (AHY/ASY) males, ranging from dark brown to mostly blackish on most FCF (HY/SY) males, largely dark brown and occasionally with some blackish on DCB (AHY/ASY) females, and generally moderate to dark brown and lacking any black on FCF (HY/SY) females.
Species account prepared by McGill Bird Observatory (2016). Last updated by Marcel Gahbauer (Mar 2022)