Gnatcatchers & Old World Warblers(Sylviidae)

Arctic Warbler

Phylloscopus borealis

Male's song is a monotonous trill with little variation. (Two songs of two birds, Denali Highway, Alaska.)
Habitat: Breeds in dense willows along stream beds.

Blue-gray Gnatcatcher

Polioptila caerulea

The gnatcatcher's common call is a nasal, high-pitched beeee, which it makes frequently as it forages in trees and shrubs. Its call may be overlooked easily in a noisy environment. (Albany County, New York.)
Habitat: In the East the Blue-Gray Gnatcatcher breeds in swampy woods.