This week’s Bird of the Week, compliments of the Weminuche Audubon Society and Audubon Rockies, is the olive-sided flycatcher.
Identifying flycatchers by appearance only can be an impossible task since so many look alike, but the olive-sided exhibits some traits that make it an easier one to learn.
First is its song, heard as “quick, three beers,” sung by a bird often perched on the highest point of a live or dead tree. Second is its upright, elongated posture and its habit of flying out to catch an insect and returning to the same perch to consume it.
The olive-gray sides and back contrasting with a white throat and belly give this flycatcher the appearance of wearing a vest. Its head often appears peaked and its bill is wide.
This bird feeds on a variety of insects with a preference for bees, wasps and ants. It is the only North American flycatcher that feeds exclusively on insects captured in flight.
For foraging and nesting, it prefers coniferous forests with openings and tall, prominent trees and snags. For an abundant insect food supply, it is often found near water.
Of the flycatcher species found in the United States, the olive-sided completes the longest migration. Some birds travel up to 7,000 miles from winter grounds in the Andes of South America to the boreal forests of Alaska. On the breeding grounds, they aggressively defend large territories, up to 100 acres per pair. They nest relatively late and only raise one brood per year, contributing to one of the lowest annual productivity rates of North American songbirds.
Severe population declines in the last five decades are most likely attributed to loss of habitat on the winter grounds in South America.
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