Hammond's flycatcher

Hammond's flycatcher (Empidonax hammondii) is a flycatcher in the family Tyrannidae. This small insectivorous bird inhabits the coniferous and mixed forests of western North America. The name of this bird commemorates William Alexander Hammond who was the surgeon general of the US Army. Hammond collected bird specimens for Spencer Fullerton Baird.

Adults are 12–14 cm long (4.7–5.5 in), span about 22 cm (8.7 in) across the wing and weigh 8–12 g (0.3–04 oz). They have grayish-olive upperparts, darker on the wings and tail, with whitish underparts; they have a conspicuous white eye ring, white wing bars, a small bill and a short tail. The breast is washed with grey and the sides of the belly with yellow. Females usually have a shorter, wider bill than males. Immature birds are similar to adults, but have broader wing bars and are more buff.

Many species of Empidonax flycatchers are very similar in appearance. Hammond's flycatchers are mainly confused with Dusky (E. oberholseri) and Gray (E. wrightii) flycatchers, which are similar in color and size and have an overlapping range. The best way to distinguish Hammond's flycatcher is by its call, breeding habitat and/or range.