Once you hear this bird, the sound will stay with you forever. The olive flycatcher is olive-brown above with white patches on his rump easily seen when he flies. The chest has a light line dividing olive sides, the tail is short and dark. They are up to 20 cm long. They are a very pretty bird.
The olive-sided flycatcher is a summer visitor to Pacific Northwest Coastal Region arriving from mid-May and staying until the end of August. They like to nest in coniferous forests around small moist areas. Look for them in the forests up high. They will be sitting in the tops of trees waiting to dash off and catch a flying insect. Large flying insects, like bees, are the preferred diet of the Olive-sided Flycatcher.
The male defends his nesting territory and attracts a mate at the same time by singing from a loudly from a high perch. Both members of the monogamous pair will aggressively defend the nest, which is an open cup of twigs, weeds, and grass, with a fine lining of animal hair and feathers. The nest is found at various heights in a conifer tree, usually on a horizontal branch well away from the trunk, hidden within the needles. The female does all the nest building and she incubates up to 4 eggs for up to 16 days. Both adults feed the young, which are ready to fledge by 21 days of age. The young continue to depend on the adults for about a week after leaving the nest, but family groups may stay together until fall migration.
At one time, the olive-sided flycatcher used areas that had recently suffered a forest fire. Now that most fires are suppressed, it often will take advantage of areas that have been recently logged, as well as other clearings and edges, which are superficially similar to fire burned areas.