Northern Prairie Wildlife Research Center
A few immatures can be identified as males by the presence of one or more light gray middle or lesser coverts emerging among the darker feathers; however, the sex of most immatures cannot be determined.
|Tertial||Black; with broad longitudinal white stripes at rachis; acutely pointed; curve distally||Dark brown; three distal with longitudinal white stripes at rachis; shafts straight; tips acutely pointed and very frayed||Black; three distal with longitudinal white stripe at rachis; acutely pointed; curve distally|
|After molt: Similar to adult male||After molt: Similar to adult female|
|Tertial coverts||Black and pointed||Dark brown and pointed; often frayed and faded||Black and pointed|
|Greater coverts||Broadly banded at tips with sharply defined white||Variably banded at tips with white which is often poorly defined and frequently with dark edging||Broadly banded at tips with sharply defined white|
|Middle and lesser coverts||Do not cover black basses of greater coverts|
|Pale grey, broadly rounded over secondaries||Dark brown; tips often ragged and frayed||Broadly rounded; dark brown but slightly paler distally|