Species: Empidonax traillii

Willow Flycatcher

Species

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Encyclopedia of Puget Sound

A flycatcher with brownish-olive upperparts (slightly grayer in the east), a whitish throat that contrasts with the pale olive breast, a pale yellow belly, and two light wing bars; generally lacks a conspicuous eye ring; as in other flycatchers, the bill is depressed and wide at the base (NGS 1983).

Classification

Kingdom

Animalia

Phylum

Craniata

Class

Aves

Order

Passeriformes

Family

Tyrannidae

Genus

Empidonax

NatureServe

Source:
ELEMENT_GLOBAL.2.103270

Classification

Other Global Common Names

Mosquero Saucero - moucherolle des saules

Informal Taxonomy

Animals, Vertebrates - Birds - Perching Birds

Formal Taxonomy

Animalia - Craniata - Aves - Passeriformes - Tyrannidae - Empidonax - each have distinctive songs and used vocal signatures to determine distributional limits of the two subspecies. The two song types seem to be largely allopatric, separated by latitude and/or elevation. The two groups appear to be evolving independently of one another and warrant at least subspecific status.

Ecology and Life History

Short General Description

Migration

false - false - true - Usually arrives on U.S. nesting grounds by May-June (Terres 1980). Present in California from late April to September (Biosystems Analysis 1989). Migrates through southern Arizona mainly in the first half of June and August-September (Phillips et al. 1964). Arrives in Washington in late May or early June. Fairly common migrant in Costa Rica, mid-August to late October (peak late September) and mid-March to late May (Stiles and Skutch 1989). In Ontario, tends to have an earlier and longer migration period in spring than Alder flycatcher (EMPIDONAX ALNORUM), and migrates significantly earlier in fall (Hussell 1991a, 1991b).

Non-migrant

false

Locally Migrant

false

Food Comments

Eats mainly insects caught in flight; occasionally berries. Bent (1942) states that 96 percent of diet is animal matter, most of which is flying insects. Once fledglings are able to forage for themselves, are less dependent on a localized, concentrated food source (USDA Forest Service 1994).

Reproduction Comments

A late breeder, eggs usually laid in mid- to late-June and young fledge in August (USDA Forest Service 1994). Clutch size is three to four. Incubation lasts 12-15 days, by female. Young are tended by both parents, leave nest at 12-15 days. Site fidelity strong in both males and females (Walkinshaw 1966). May incur a high rate of cowbird parasitism (e.g., Sedgwick and Knopf 1988, Harris 1991, Brown 1988). Sometimes polygynous and may maintain polygynous trios, possibly a response to narrow habitats with high habitat productivity or other factors (Prescott 1986, Sedgwick and Knopf 1989). Singing, unmated males may be present on breeding grounds, and single pairs may breed in absence of other individuals (USDA Forest Service 1994). On one study in Ohio and Nebraska, 91 nests had 272 eggs from which 99 young fledged (36.4 percent success) and 39.5 percent of nests produced at least one young; 96 eggs and 41 nestlings were depredated (50.4 percent; Holcomb 1972).

Ecology Comments

BREEDING: Conduct most of their activity within their defended territory, but both male and female will also use adjacent areas, especially when feeding young; territory defense declines once young are fledged (USDA Forest Service 1994). In Ontario, territory size ranged from about 0.1 hectares to 0.47 hectares and averaged 0.35 hectares (Prescott and Middleton 1988); in southern Michigan, territories averaged 0.7 hectares (Walkinshaw 1966). In California, territories ranged from 0.1 hectares to 0.9 hectares, and averaged 0.2 hectares in Fresno County and 0.4 hectares on the Truckee River (USDA Forest Service 1994). Where breeding range overlaps with alder flycatchers (EMPIDONAX ALNORUM), may show territorial defense toward the other species (Prescott 1987). NON-BREEDING: In Panama, winter home range estimated to be about 1100 square meters (Gorski 1969).

Length

Weight

Conservation Status

NatureServe Global Status Rank

Global Status Last Reviewed

2005-01-28

Global Status Last Changed

1996-12-02

Distribution

Conservation Status Map

Global Range

H - >2,500,000 square km (greater than 1,000,000 square miles) - H - BREEDING: central British Columbia across southern Canada and northern U.S. to New Brunswick, Prince Edward Island, and Nova Scotia, south to southern California, northern Baja California, northern Sonora, southern Arizona and New Mexico, western and central Texas, Arkansas, northern Georgia, and eastern Virginia (AOU 1998). NON-BREEDING: Nayarit and southwestern Oaxaca south to Panama and northwestern Colombia (Stiles and Skutch 1989, AOU 1998). Subspecies brewsteri: Breeding distribution is west of the Cascades and in the Sierra Nevada from southwestern California to southwestern British Columbia (Sedgwick 2000).

Global Range Code

Global Range Description

>2,500,000 square km (greater than 1,000,000 square miles)

ELEMENT_GLOBAL.2.103270