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*BLACK-BELLIED WHISTLING DUCK  Dendrocygna autumnalis 46–51cm.

Distinctive, long-legged, boldly patterned duck with coral-red bill. Varied

freshwater and brackish habitats, from lakes and roadside ditches to flooded

fields, mangroves. Mostly feeds by night, roosting by day in vegetation, often in

trees. Flocks locally may be in 1000s. In flight, note bold white stripe on

upperwing, dark underwing. Juv. duller overall with grayish bill, ghosting of

adult plumage pattern; like adult within a few months. SOUNDS: High piping

whistles, usually in short series of notes, mainly given in flight. STATUS: Fairly

common to locally common on both slopes; small numbers increasingly seen

inland, locally to 1500m. (Mexico and s. US to S America.)

FULVOUS WHISTLING DUCK  Dendrocygna bicolor 48–54cm. Distinctive,

long-legged, overall tawny duck found in freshwater and brackish habitats,

from lakes and roadside ditches to flooded fields, mangroves; mostly feeds at

night. Often in small flocks, mixing readily with more numerous Black-

bellied Whistling Duck. In flight, note solidly dark wings, white U at tail base.

SOUNDS: Nasal, slightly hoarse, usually 2-syllable whistles, distinct from high

piping of Black-bellied Whistling Duck. STATUS: Uncommon locally in nw.

lowlands; very rare to rare wanderer elsewhere. (Tropical Americas, Africa,

Asia.)

DABBLING DUCKS

(6+ species). All are winter migrants to Costa Rica, overall declining there as

birds remain farther north in winter; recent pulses (since 2010) of larger numbers probably related to

droughts in sw. US and Mexico. Best identified by overall size and shape, wing patterns in flight; also

note bill shape and color, leg color. Takeoff typically direct from water, without a running start, and

often vocalize when disturbed. Formerly all species placed in genus Anas.

NORTHERN PINTAIL  Anas acuta 51–58cm. Winter migrant to varied wet­

land habitats, especially shallow freshwater. Feeds mainly by dabbling and up-

ending. Elegant and long-necked with tapered tail, slender blue-gray bill,

grayish legs. Adult male distinctive (imm. male resembles adult by early winter);

other plumages overall paler and grayer than most dabbling ducks (but can be

stained rusty in fall–early winter, cf. Fulvous Whistling Duck), best identified

by overall shape, bill shape and color, wing pattern: underwings dusky overall,

upperwing has broad white trailing edge to speculum. SOUNDS: Male gives high

rolled wirrrh; female a slightly reedy quacking kwerrk. STATUS: Uncommon and

local late Oct–early Mar in nw. lowlands, rare and irregular elsewhere; to 1500m. (Holarctic; winters to

Cen America.)

GREEN-WINGED TEAL  Anas [crecca] carolinensis 35–38cm. Rare winter migrant to varied wetland

habitats, especially with muddy shallows. Feeds mainly by dabbling. Small, compact, and overall dark,

with grayish legs. Adult male distinctive (imm. male resembles adult by mid-winter); female told by

small size, buffy to whitish streak at sides of undertail coverts, dark upperwing with buffy leading edge to

speculum. Cf. Blue-winged and Cinnamon Teal, which have larger bills, yellowish legs, pale blue forewing

panels. SOUNDS: Male gives high, reedy, piping kreek; female a low rough quack. STATUS: Very rare and

irregular Nov–Mar in nw. lowlands; exceptional elsewhere, mainly on Pacific slope. (Breeds N America,

winters to Cen America.)

AMERICAN WIGEON  Mareca (Anas) americana 43–51cm. Winter migrant to

wetlands, lakes, adjacent flooded and grassy fields; often in small flocks. Feeds

by grazing and dabbling. Note fairly stocky shape with small blue-gray bill

tipped black, pointed tail, gray legs; white forewing of adult male striking in

flight. Adult male distinctive (imm. male resembles adult by early winter);

female told by small gray bill, overall ruddy plumage with grayer head and

neck, rather plain breast and sides. SOUNDS: Male has high breathy whistle,

whiih, often doubled or in short series; female a low grunting quack.

STATUS: Uncommon to rare and local late Oct–early Apr in nw. lowlands; very

rare elsewhere, occasionally to 1500m in Central Valley. (Breeds N America,

winters to Cen America.)