Willow flycatcher

Description

The willow flycatcher (Empidonax traillii) is a small insect-eating,neotropical migrant bird of the tyrant flycatcher family.There are four subspecies of the willow flycatcher currently recognized,all of which breed in North America (including three subspecies that breed in California).Empidonax flycatchers are almost impossible to tell apart in the field so biologists use their songs to distinguish between them.The binomial commemorates the Scottish zoologist Thomas Stewart Traill.Adults have brown-olive upperparts,darker on the wings and tail,with whitish underparts;they have an indistinct white eye ring,white wing bars and a small bill.The breast is washed with olive-gray.The upper part of the bill is gray;the lower part is orangish.At one time,this bird and the alder flycatcher (Empidonax alnorum) were considered to be a single species,Traill's flycatcher.The willow and alder flycatchers were considered the same species until the 1970s.Their song is the only reliable method to tell them apart in the field.