Photo courtesy Barry Knot
This week’s Bird of the Week, compliments of the Weminuche Audubon Society and Audubon Rockies, is the cordilleran flycatcher.
With over 400 species of birds, most of which live in South America, the family of birds known as tyrant flycatchers is the largest. The majority of birds in this group feed primarily by sallying out from a perch to capture insects in the air. Lacking the sophisticated vocal capabilities of other songbirds, they sing a simple song.
The tyrant flycatcher family is further divided into more than 100 groups. The cordilleran flycatcher belongs to one of these, the group of look-alike birds that make up the Empidonax genus. Confusing, difficult and impossible are all words associated with attempting to differentiate these small olive-colored birds with pale bellies, wingbars and eyerings. The eyering of the cordilleran flycatcher is shaped like a teardrop.
The name cordilleran comes from the Spanish word for mountain range and refers to the stretch made by the Rocky Mountains and Sierra Madre where these birds breed. Little is known of the winter ecology of these flycatchers that spend most of the year in Mexico, where they are difficult to distinguish from other flycatchers in appearance.
In summer, cordillerans breed in high-elevation coniferous and mixed forests, often along creeks, streams and rivers, where they build a nest on a ledge, in a crevice in a rock stream bank, on a stump, in the root ball of a fallen tree or sometimes in the fork of a tree. They will also nest near humans on a rafter, a window ledge or an outside light fixture.
Empidonax flycatchers, empids for short, are best identified by the habitat they occupy and differences in voice. The simple, two-part whistle of the cordilleran flycatcher can be heard throughout the day and is easy to learn. Phone apps like Merlin, which match bird song with species, have become popular tools for identifying birds and invaluable in distinguishing those tricky flycatcher species that are so similar in appearance.
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