- 5.1–6.7 in
- 7.5–9.4 in
- 0.4–0.6 oz
- Moucherolle des saules (French)
- Mosquero saucero (Spanish)
- Flycatcher songs are innate, not learned like those of most songbirds. Young Willow Flycatchers reared in captivity with Alder Flycatcher tutors sang typical Willow Flycatcher songs.
- When the two species are found together, the Willow Flycatcher will keep Alder Flycatchers out of its territory. But it expends more effort to keep out other Willow Flycatchers.
- If a Brown-headed Cowbird lays its eggs in the nest of a Willow Flycatcher, the flycatcher may bury the cowbird eggs in the nest lining, or even build a completely new nest over the top of the first one.
- The oldest recorded Willow Flycatcher was a female, and at least 11 years old when she was recaptured and rereleased during banding operations in California.
- Breeds in moist, shrubby areas, often with standing or running water.
- Winters in shrubby clearings and early successional growth.
Mostly insects, some berries in fall.
- Clutch Size
- 3–5 eggs
- Egg Description
- Creamy white or buff dotted with dark irregular markings around large end.
- Condition at Hatching
- Helpless and with only small patches of down.
Nest built low in crotch of bush or small tree near water, on outer edge of shrub. Nest an open cup woven of weed stems, plant fibers, pine needles, shredded bark, and grass; lined with feathers, hair, rootlets, and fine materials.
Captures insects by hawking and hover-gleaning.
Willow Flycatcher populations declined by 51% between 1966 and 2014, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 9.1 million birds, with 67% spending part of the year in the U.S., 16% in Mexico, and 33% breeding in Canada. The species rates a 10 out of 20 on the Continental Concern Score. The Southwestern subspecies of Willow Flycatcher has been extirpated from much of its original range, and is federally listed as Endangered. It is also on the Audubon Watchlist, and is on the 2014 State of the Birds Watch List, which lists bird species that are at risk of becoming threatened or endangered without conservation action.
- Sedgwick, J. A. 2000. Willow Flycatcher (Empidonax traillii). In The Birds of North America, No. 533 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.
- U.S. Fish & Wildlife Service, ECOS-Environmental Conservation Online System, Southwestern Willow flycatcher (Empidonax traillii extimus).