Field Sparrow - Spizella pusilla

Field Sparrow has a partial to incomplete molt that may not finish until after migration, and limited prealternate molts that are restricted to the face and throat and continue into summer. Most individuals can be aged reliably through molt limits. Although females are on average smaller and slightly duller in plumage, the sex of most individuals is reliably determined only via brood patch / cloacal protuberance during the breeding season.

Quick tips

• Look at the tail - uniformly narrow and pointed rectrices OR contrastingly fresh and broad central rectrices are indicative of FCF/FCU (HY/SY), but note that both FCF/FCU (HY/SY) with an extensive preformative molt and DCB/DCU (AHY/ASY) individuals can have uniformly broad and rounded rectrices .
• Examine the secondaries and primaries - most FCF/FCU (HY/SY) birds have at least a few fresh and dark replaced inner secondaries (and sometimes also outer primaries) that contrast with the paler central wing feathers; on DCB/DCU (AHY/ASY) birds the primaries and secondaries are uniform.
• Check the primary coverts - they are relatively narrow, pale, and lacking edging on FCF/FCU (HY/SY) birds, but relatively broad, dark, and with rufous edging on DCB/DCU (AHY/ASY) birds.

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