シロボシバト 対 アマゾンカッコウ

The most reliable field mark to separate Spot-winged Pigeon from Guira Cuckoo is the pigeon’s bold, creamy white spots on the dark wing coverts and a conspicuous white wing band (especially in P. m. albipennis), visible both perched and in flight, versus the cuckoo’s streaked dark brown upperparts and long, white-tipped tail. Juvenile plumages are not dramatically different from adults in either species, but the pigeon’s wing spots and overall structure remain distinctive at all ages. Guira Cuckoo is much lighter-bodied, with a prominent orange-rufous crest, yellow bill and eye-ring, and a long, broad tail, giving it a very different jizz from the compact, heavy pigeon. In the field, the pigeon is usually seen feeding on the ground in flocks, while the cuckoo is often noisy, arboreal, and moves in loose groups.

1. Look for the bold white spots and/or white wing band on the folded wing of Spot-winged Pigeon (all ages, especially P. m. albipennis). Guira Cuckoo never shows these marks; its upperwing is streaked brown with no pale spots or bands.
2. Check overall structure: Spot-winged Pigeon is stocky and heavy-bodied, with a short neck and broad wings. Guira Cuckoo is slender, with a long, broad tail and a more elongated appearance.
3. Tail shape and pattern: The pigeon has a dark gray, relatively short tail, while the cuckoo’s tail is long, broad, dark brown with a conspicuous white tip (all ages).
4. Head and crest: Guira Cuckoo has a prominent orange-rufous crest, often raised, and a yellow to orange bill and eye-ring. Spot-winged Pigeon lacks a crest and has a plain, grayish head (purplish-pink in nominate males).
5. Bill color: The pigeon’s bill is dark, while the cuckoo’s is yellow to orange.
6. Eye-ring: Guira Cuckoo has a thin, featherless yellow eye-ring; Spot-winged Pigeon does not.
7. Plumage color: Spot-winged Pigeon has a combination of dull purplish-pink (nominate) or blue-gray (albipennis) on the head and underparts, with creamy white wing spots. Guira Cuckoo is streaked brown above and whitish-buff below, with no pink or blue-gray tones.
8. Juvenile confusion: Both species’ juveniles are duller than adults, but the pigeon’s wing spots persist (though less crisp), while the cuckoo’s streaking and tail pattern are present from a young age.
9. Flight style: Spot-winged Pigeon flies strongly and directly, often in flocks; Guira Cuckoo’s flight is weak, fluttery, and covers short distances.
10. Behavior: Pigeon is usually seen on the ground in open areas, feeding in groups. Cuckoo is more arboreal, perching in trees or bushes, and is often noisy and social.
11. Vocalizations: A loud, shrill, wailing or whistling call points to Guira Cuckoo. Pigeon calls are lower and more subdued.
12. Habitat context: In urban parks or gardens, especially in eastern South America, Guira Cuckoo is more likely. In open fields or agricultural land, especially in southern South America, Spot-winged Pigeon is more likely.
13. Sex differences: Both species show little sexual dimorphism in the field, though female Guira Cuckoo is slightly larger and female Spot-winged Pigeon is duller-headed.
14. Group composition: Both can be seen in flocks, but the pigeon’s flocks are often tight and ground-feeding, while the cuckoo’s groups are looser, more arboreal, and highly vocal.
15. Odor: Guira Cuckoo is noted for a strong, pungent odor (not a field mark for most observers, but unique among these two).

Spot-winged Pigeon is a much heavier bird, with adults weighing 308–347 g (nominate subspecies) compared to the Guira Cuckoo's 134 g. Both species are similar in length (32–34 cm), but the pigeon is stockier and more robust, while the cuckoo is slender with a proportionally longer tail. The pigeon’s bulk is especially apparent when perched or walking on the ground, while the cuckoo appears lankier and lighter.

• Juvenile and immature plumage: Both species’ juveniles resemble adults but are duller. Spot-winged Pigeon juveniles have drab gray heads and breasts, but still show the pale wing spots (though less crisp), while Guira Cuckoo juveniles are only slightly duller than adults and maintain the streaked upperparts and long, white-tipped tail.

• Adult plumage: Spot-winged Pigeon (nominate) has a dull purplish-pink head and breast, gray underparts, dark brown upper back and wing coverts with creamy white spots, and a bluish-gray rump. The folded wing shows a bold white band in P. m. albipennis. Guira Cuckoo has dark brown upperparts streaked with white, a whitish-buff throat and underparts, a long dark brown tail with a white tip, and a prominent orange-rufous crest. The pigeon’s wing pattern is diagnostic: look for the pale spots and/or white band, which are never present on the cuckoo.

• In flight: The pigeon’s wings are mostly black above with pale spots and a white band (especially in P. m. albipennis), contrasting with the Guira Cuckoo’s plain, streaked brown upperwing and long, broad, white-tipped tail.

Spot-winged Pigeon is typically seen feeding in flocks on the ground, moving with a heavy, deliberate gait. In flight, it is strong and direct, with broad wings and a steady, purposeful flight. Guira Cuckoo is gregarious, often in noisy flocks, and is more arboreal, hopping or gliding between perches and sometimes foraging on the ground. Its flight is weak and fluttery, usually covering only short distances. The cuckoo is also known for its conspicuous, shrill vocalizations and frequent crest-raising.

Both species occur in open or semi-open habitats in South America, but Spot-winged Pigeon is more likely in agricultural fields, grasslands, and open country, especially in southern South America. Guira Cuckoo favors open and semi-open areas, including suburban parks and gardens, and its range has expanded with deforestation. The cuckoo is more likely to be seen in trees or bushes, while the pigeon is usually on the ground or perched in open areas.

Guira Cuckoo has a loud, long, shrill call described as a cross between a whistle and a wail, often given in chorus by groups. Spot-winged Pigeon’s vocalizations are not described in the provided notes, but pigeons generally have low, cooing calls, which are very different from the cuckoo’s raucous, high-pitched sounds. In the field, hearing a shrill, wailing call is a strong indicator of Guira Cuckoo.