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The most reliable field mark to separate Red-billed Pigeon from Band-tailed Pigeon is the presence of a thin white nape collar and green neck iridescence on adult Band-tailed Pigeon, which Red-billed Pigeon always lacks. Juvenile Band-tailed Pigeons also show a scaly appearance above and lack the collar, but Red-billed juveniles are duller overall with browner upperparts and lack any scaly effect. Bill color is another key: Red-billed Pigeon has a red bill with a yellow tip, while Band-tailed Pigeon shows a yellow bill (sometimes with a black tip in northern subspecies). In flight, Band-tailed Pigeon shows a broad pale tail band, while Red-billed Pigeon’s tail is more uniformly colored. Both are large, robust pigeons of similar size, but their structure and habitat preferences can help in context.

1. White nape collar (adult Band-tailed only): Look for a thin white collar on the nape and green neck iridescence in Band-tailed Pigeon adults; Red-billed Pigeon never shows this feature at any age.
2. Tail pattern in flight: Band-tailed Pigeon shows a broad pale terminal tail band with a darker subterminal band; Red-billed Pigeon’s tail is more uniformly colored and lacks a contrasting band.
3. Bill color: Red-billed Pigeon has a red bill with a yellow tip (all ages); Band-tailed Pigeon has a yellow bill, sometimes with a black tip (northern subspecies), but never red.
4. Juvenile upperparts: Juvenile Band-tailed Pigeon has pale-edged, scaly-looking upperparts and lacks the white collar; juvenile Red-billed Pigeon is duller overall, with brownish wings and mantle, but not scaly.
5. Head and neck color: Red-billed Pigeon adults have a maroon to purple head and neck; Band-tailed Pigeon is gray with a faint pinkish or purple-gray cast, never rich maroon.
6. Belly color: Band-tailed Pigeon has a nearly white belly; Red-billed Pigeon’s belly is blue-gray, not white.
7. Eye and orbital ring: Red-billed Pigeon has pale red eyes with an orange orbital ring; this is less distinctive in Band-tailed Pigeon.
8. Sex differences: Female Red-billed Pigeons are duller on the head and neck than males, but this is subtle; Band-tailed Pigeon males may be slightly larger and pinker, but sexes are similar.
9. Wing structure: Band-tailed Pigeon has thick-based, pointed wings; Red-billed Pigeon is also robust but does not show this feature as strongly.
10. Habitat context: In lowland dry forests or riverside woods, suspect Red-billed Pigeon; in montane or oak forests, Band-tailed is more likely.
11. Flight sound: Red-billed Pigeon may produce a wing-clap on takeoff, which can be a clue if heard.
12. Vocalization: If you hear a long, high-pitched 'coooo' followed by three quick notes, it is Red-billed Pigeon.
13. Group behavior: Band-tailed Pigeon may nest in loose colonies; Red-billed Pigeon is more often solitary or in pairs.
14. Seasonal presence: Red-billed Pigeon is rare in winter in most of its range; Band-tailed Pigeon’s seasonal movements depend on region, but both can be absent in winter in some areas.
15. Size: Both are similarly large and robust; do not rely on size alone for separation.

Both species are among the largest New World pigeons, with substantial overlap in size. Red-billed Pigeon measures 30–37 cm in length and weighs 230–425 g; Band-tailed Pigeon is 33–40 cm long and weighs 226–460 g. Band-tailed may average slightly larger, but size alone is not a reliable field mark between them. Both appear large and robust in the field.

• Juveniles: Juvenile Band-tailed Pigeons have pale feather edges above, giving a scaly or mottled look, and lack both the white nape collar and neck iridescence. Juvenile Red-billed Pigeons are duller overall, with dark, dusky shoulders and a browner mantle and wings, but do not show a scaly effect.
• Adults: Adult Band-tailed Pigeons have a thin white collar on the nape and green iridescence on the neck, plus a broad pale tail band with a darker subterminal band. Their overall color is gray with a faint pinkish cast on the head and breast, and a nearly white belly. Adult Red-billed Pigeons are darker slate-gray with a maroon to purple head, neck, and wing coverts, a blue-gray belly and tail coverts, and lack any iridescent collar or nape mark. Their bill is red with a yellow tip, while Band-tailed's is yellow (sometimes with a black tip).

Both species are robust pigeons with strong, direct flight. Band-tailed Pigeon has thick-based, pointed wings and a broad tail, often showing the pale tail band in flight. Red-billed Pigeon also has strong flight and can produce a wing-clap sound on takeoff. Both perch in trees, but Band-tailed Pigeons may form small colonies when nesting, while Red-billed Pigeons are often seen singly or in pairs. No major behavioral differences are diagnostic in brief field views.

Red-billed Pigeon is most often found in dry forests, riverside woodlands, and lowland areas from southern Texas through Mexico and Central America. Band-tailed Pigeon prefers montane forests, oak woodlands, and higher elevation habitats, especially in western North America and Central America. Overlap is possible in some regions, but context can help: Band-tailed is more likely in upland or montane forests, Red-billed in lowland dry woods or riparian zones.

Red-billed Pigeon gives a distinctive, long, high-pitched call: a drawn-out 'coooo' followed by three quick 'cuk-c'-c'-coo' notes, with an ascending pattern. Band-tailed Pigeon's vocalizations are not described in the provided notes, so voice is only diagnostic if Red-billed's unique call is heard.