Generally, coverts of adults are somewhat wider and tend to lie more smoothly on the wing and the dark blue usually extends on to the third row of coverts and extends farther distally than on wings of immatures. Age Determination of Females Immature tertials are pale bronze with pointed, usually frayed, tips. Immature tertial coverts are narrow and yellow-green. Most immatures replace both tertials and tertial coverts with purplish red adult-type feathers by late October. Usually, the blue iridescence is confined to two rows of coverts and is restricted to the proximal half of the immature wing.
Adult coverts are somewhat wider and tend to lie more smoothly on the wing.
Dark blue usually extends onto the third row of coverts and extends farther distally than on the immature coverts. Their wings cannot be distinguished from those of adults.