Size: L: 14 cm. Wt: 10-11 g. Males and females are similar. This species is seasonally dimorphic.
Breeding Adult: upperparts brown, with reddish cap and yellow eyebrow; underparts yellow, with brown streaks on breast and sides; bill narrow, pointed; legs blackish
Fall Adult/Juvenile: upperparts brown to grey-brown, with little or no reddish on crown, and white eyebrow; underparts greyish except for yellow undertail coverts; bill and legs as in breeding adult
Nestling: altricial and downy; down is mouse-colored, with hints of pale reddish-brown