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*NORTHERN TROPICAL PEWEE  Contopus [cinereus] bogotensis 13–14.5cm.

Woodland and edge, adjacent second growth, pastures with hedgerows, scattered

trees; mainly mangroves in northwest. See genus note (p. 306). Low to high, of-

ten on fences. Slightly more compact and richly colored than Eastern and West-

ern Pewees; note shorter primaries, darker crown, voice. Also cf. migrant Willow

and Alder Flycatchers, readily told by habits, voice. SOUNDS: Short, slightly over-

slurred ringing trill, suggesting Middle American Kingbird; high, sharply over-

slurred pyeép. Song a high, vaguely disyllabic, upslurred pseep or p’seíh, every 1–3

secs; at longer intervals after dawn. STATUS: Fairly common to uncommon in

humid lowlands, to 1500m; scarce and local on drier n. Pacific slope. (Mexico to n. South America.)

WESTERN PEWEE (WOOD PEWEE)  Contopus sordidulus 13.5–15cm.

Wooded and semi-open foothill and highland habitats with hedges, scattered

trees, fences. See genus note (p. 306). Averages duskier and grayer than Eastern

Pewee, with more strongly vested underparts, but ID best by voice. Note long

wings vs. Northern Tropical Pewee, also voice. Cf. shorter-winged Willow and

Alder Flycatchers, readily identified by habits. Imm. has fresher plumage, buff

wingbars. SOUNDS: Overslurred, burry drawled brréeu or bzzhiu, distinct from

Eastern Pewee; less often a plaintive, slightly upslurred peéur, suggesting Eastern

but slightly lower, shorter, less inflected. STATUS: Fairly common to common

Aug to mid-Nov, late Mar–May, on both slopes, mainly above 700m; rare in winter, mainly on Pacific

slope. (Breeds w. N America to Mexico, winters S America.)

EASTERN PEWEE (WOOD PEWEE)  Contopus virens 13.5–15cm. Wooded

and semi-open lowland and foothill habitats with hedges, scattered trees,

fences. See genus note (p. 306). Very similar to Western Pewee, and often not

separable in field unless heard. Note long wings vs. Northern Tropical Pewee,

also voice. Cf. Willow and Alder Flycatchers, readily identified by habits, voice.

Imm. has fresher plumage, buff wingbars. SOUNDS: Plaintive upslurred p’weée

or du-weée, clearer and higher than Western Pewee; rarely a clipped puik.

STATUS: Fairly common to common mid-Aug to mid-Nov, Mar–May, on both

slopes to 1500m, in smaller numbers to 2500m; rare in winter, mainly below

1200m. (Breeds e. N America, winters S America.)

EMPIDS (GENUS EMPIDONAX) (8 species). Small flycatchers with pale wingbars and usually

pale eyerings; crown often slightly peaked but not distinctly crested. Unlike pewees, empids do not return

repeatedly to the same prominent perches and they tend to perch more inconspicuously, several species

inside forest or woodland. Habitually flick tails up and twitch wings, unlike pewees. Best identified by voice

and structure; also note habitat, overall plumage tones (grayish and whitish vs. greenish and yellowish).

WILLOW FLYCATCHER  Empidonax traillii 12.5–14cm. Nonbreeding migrant

in open and semi-open habitats with hedgerows, scattered trees, second growth,

marshes. See genus note. Weak eyering (often appears plain-faced, cf. pewees),

whitish throat, and relatively dull wingbars separate Willow and Alder Flycatchers

from other migrant empids. Some Willows (from w. N America) duller and

browner than Alder, with duller wingbars; others (from e. N America) only safely

told from Alder by voice. SOUNDS: Sharply upslurred, mellow whit or more liquid

whuit, similar to Least Flycatcher. STATUS: Fairly common mid-Aug to Oct, mid-

Mar to May on both slopes, to 1500m; uncommon locally in winter in nw.

low­lands and on Pacific slope. (Breeds N America, winters Mexico to S America.)

ALDER FLYCATCHER  Empidonax alnorum 12.5–14cm. Transient migrant in

open and semi-open habitats with hedgerows, scattered trees, second growth.

See genus note and under Willow Flycatcher. Averages brighter, more con­

trasting than eastern Willow, but reliably separated in field only by voice; also cf.

Least Flycatcher. SOUNDS: High, sharply overslurred piic or peek, unlike other

Costa Rican empids. STATUS: Fairly common late Aug–early Nov on Caribbean

slope, uncommon on Pacific slope, rarely to 2000m; uncommon to fairly

common on both slopes, Mar–May. (Breeds n. N America, winters S America.)