Willow flycatcher

Empidonax traillii

SUBFAMILY

Fluvicolinae

TAXONOMY

Empidonax traillii Audubon, 1828. Five subspecies. OTHER COMMON NAMES

French: Moucherolle des saules; German: Weidentyrann; Spanish: Mosqueta Saucera.

PHYSICAL CHARACTERISTICS

5.75 in (14.5 cm). Plumage includes a brownish to brownish green head, brownish green upperparts, dark wings with buff

to yellow wing bars, pale yellow trim on tertials and secondaries, a dark tail, a thin, pale eye ring, pale lores, whitish un-derparts, and dusky side flanks tinged with yellow. Feet and legs are blackish, and bill is blackish with a yellowish pink lower mandible. Plumage color varies somewhat with region; for example, northwestern races have a dark head, while southwestern races have a pale head. Sexes are similar.

DISTRIBUTION

Breeding is mostly restricted to the continental United States, including the northwestern states, Rocky Mountains, Great Plains, Midwest, and northeastern regions.

HABITAT

Prefers shrubs and undergrowth, willow thickets, fresh water marshes, ponds, rivers, and lakes.

BEHAVIOR

Silent in migration, but otherwise sings a sharp "fitz-bew!" or "fitz-be-yew!" Also releases a loud "whit!" Perches low, below top of vegetative layer; chooses an exposed perch to sing. During courtship, males chase females in flight.

FEEDING ECOLOGY AND DIET

Perches to spot prey, sallies forth to catch prey in midair, and returns to the same perch. Feeds on flying insects, insects gleaned from foliage, spiders, and occasional berries.

REPRODUCTIVE BIOLOGY

Monogamous breeders. Nest is cup-shaped and compact, often with hanging streamers, built by female in the fork of a deciduous tree. One clutch per year of two to four eggs, incubated by female for 12 to 15 days. Juveniles remain in the nest for 12 to 14 days, fed by both sexes.

CONSERVATION STATUS

Not threatened, though populations on the west coast are declining due to loss of streamside habitat, particularly caused by grazing animals. Nests are parasitized by the brown-headed cowbird (Molothrus ater). May also be imperiled by loss of tropical wintering habitat due to deforestation.

SIGNIFICANCE TO HUMANS None known. ♦

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