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THICK-KNEES (BURHINIDAE; 1 SPECIES) Small family of large terrestrial

‘shorebirds’ found worldwide in warmer climates. Ages differ slightly, sexes similar; like adult

in 1st year; despite the name, ‘knees’ not especially thick.

DOUBLE-STRIPED THICK-KNEE  Burhinus bistriatus 45–50cm. Large,

cryptic, long-legged nocturnal bird of grassland, savanna, ranchland with

scattered trees and bushes; usually not close to human habitation. Usually in

pairs or small groups; spends the day standing or sitting quietly, often in the

shade of bushes, fence posts. Runs well and fast, in preference to flying. No

truly similar species in Costa Rica, but at night cf. imm. Yellow-crowned Night

Heron (p. 82), which can be well away from water. Juv. has subtly different head

pattern without pronounced double stripes, soon like adult. SOUNDS: Heard

mainly at night, sometimes in day when alarmed. Far-carrying, clipped barks

and clucks, often in persistent, fairly rapid series, kyeh-kyeh...; at a distance might suggest frogs.

STATUS: Fairly common but often local on n. Pacific slope; smaller numbers spreading e. into n. Caribbean

lowlands and w. Central Valley, also s. along Pacific slope; rarely to 1000m. (Mexico to S America.)

STILTS AND AVOCETS (RECURVIROSTRIDAE; 2 SPECIES) Small

worldwide family of elegant, long-legged shorebirds found in warmer climates. Ages/sexes

differ slightly; adult appearance attained in 1st year; avocet has seasonal plumage changes.

BLACK-NECKED STILT  Himantopus mexicanus 36–41cm. Essentially un­

mistakable, visually elegant but vocally irritating large shorebird with

improbably long, hot-pink legs. Breeds at salt ponds, shallow lagoons; ranges to

varied wetland habitats, less frequent in freshwater and on open coasts. Often in

flocks, associating readily with other shorebirds, and breeds colonially. Male has

glossy black back and wings, breast often flushes pink on breeding birds; female

and imm. have brownish back; juv. has weaker dark head and neck pattern,

whitish trailing edge to secondaries; like adult in 1st year. SOUNDS: Varied, often

persistent yapping and clucking calls, especially when nesting, have earned the

nickname ‘Marsh Poodle.’ Also high piping piik, reminiscent of Long-billed Dowitcher. STATUS: Fairly

common to common nonbr. migrant on both slopes and locally inland, mainly Aug–Apr; breeds locally,

mainly in nw. lowlands; to 1500m. (Americas.)

AMERICAN AVOCET  Recurvirostra americana 40–43cm. Elegant and essentially unmistakable migrant

shorebird with fine upcurved bill, boldly pied plumage. Feeds by sweeping bill side-to-side through

water. Usually singles, rarely small groups, at shallow lakes, salt ponds, other wetland habitats, associating

readily with other large shorebirds, especially stilts. Sexes similar, but male has straighter bill than female;

breeding plumage attained Feb–Apr. Juv. (Aug–Oct) has rusty tinge to head and hindneck, like nonbr.

adult by early winter. SOUNDS: Overslurred piping kleéh, singly or in series, at times persistently repeated.

STATUS: Rare and irregular nonbr. migrant to nw. lowlands, mainly Aug–Apr. (Breeds N America to

Mexico, winters to Cen America.)