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PEREGRINE FALCON Falco peregrinus 38–51cm, WS 96–119cm. Wide
spread, powerful migrant falcon of varied open and semi-open habitats,
especially wetlands, coastal lagoons. Soars on flattish or slightly raised wings;
wingbeats smooth and powerful. Hunting flights notably swift, including steep
dives; regularly hunts bats late in day, more so than Bat Falcon. Often perches
on utility poles, antennas in towns; not on wires. Only large falcon regular in
Costa Rica, cf. very rare, much more lightly built and long-tailed Aplomado
Falcon. Note adult Peregrine’s dark hood, barred underparts. Male obviously
smaller than female when seen together. Attains adult appearance in 2nd year.
SOUNDS: Mostly quiet; harsh screams and hoarse whistles in interactions. STATUS: Uncommon Sep–Apr
on both slopes, to 2000m; more widespread and numerous Sep–Oct, Mar–Apr in migration, especially
along Caribbean coast. (Almost worldwide.)
APLOMADO FALCON Falco femoralis 38–46cm, WS 81–93cm. Very rare. Attractive, lightly built, and
long-tailed falcon of open habitats, especially ranchland and wetlands with scattered trees. Perches on
trees, low shrubs, roadside wires and posts. Flight smooth and powerful, dashing after small birds, hunting
over burning fields, and soaring in a leisurely manner, snatching insects in flight. Note very long tail,
bold white eyebrow, black breast band, cinnamon belly; also white trailing edge to wings, narrow white
tail bars. Cf. larger and stockier Peregrine Falcon. Juv. has browner upperparts, heavier dark streaking
on chest, buff wash to face and breast in fresh plumage; blue-gray cere and eyering become yellow like
adult over 1st year; attains adult appearance in 2nd year. SOUNDS: Mostly quiet; fairly high screaming
calls mainly in interactions. STATUS: Very rare fall–winter visitor to nw. lowlands, exceptionally to Central
Valley; mainly 1st-year birds, all since 2010. (Mexico and sw. US to S America.)
OSPREY (PANDIONIDAE; 1 SPECIES) Small but virtually worldwide family of
fish-eating raptors, sometimes subsumed into hawk family. Ages/sexes differ slightly, female
larger; like adult in 2nd year.
*(WESTERN) OSPREY Pandion haliaetus 56–66cm, WS 149–175cm. Dis
tinctive, long-winged, fish-eating migrant raptor found along coasts and rivers,
at lakes, reservoirs, and near any water body likely to hold fish. Note white head
and underparts with dark mask; grayish feet. Perches on prominent snags,
utility poles. Soars easily on crooked and slightly arched wings; as likely to be
mistaken in flight for a large gull as for any other raptor. Feeds from flight,
splashing feet-first to snatch fish near surface. Female averages heavier dark
breast streaking than male; juv. has buff wash to breast and neat pale tips to
upperparts, lost through 1st winter. SOUNDS: Clear to slightly hoarse ringing
whistles and downslurred yelps, often in slightly intensifying series. STATUS: Uncommon to fairly common
Sep–Apr (imms. regularly remain through summer) on both slopes; smaller numbers inland to 2500m,
occasionally higher, especially during migration. (Breeds N America to Mexico and Caribbean, migrant
s. to S America; also Old World.)
