ニシルリガシラタイヨウチョウ 対 キノドタイヨウチョウ

The most reliable field mark between Cameroon Sunbird and Buff-throated Sunbird is the combination of plumage coloration and structural differences, especially in adult males. Cameroon Sunbird males show a metallic steel-blue upper breast with violet reflections and olive-green body, while Buff-throated Sunbird males (not described in detail here, but known from other sources) have a distinctive buff-colored throat and more extensive metallic coloration. Females and immatures of Cameroon Sunbird are generally duller olive-brown with yellow-tinged underparts, and juveniles are even duller with a bright yellow belly. Structural differences include the bill: Cameroon Sunbird females and immatures have a shorter, less curved bill compared to the long, decurved bill typical of Buff-throated Sunbird. Both species overlap in range in Cameroon and Nigeria, but Cameroon Sunbird is restricted to montane forests, while Buff-throated Sunbird is found in a wider range of lowland and secondary habitats.

1. Adult male breast color: Cameroon Sunbird males show a metallic steel-blue upper breast with violet reflections and olive-green body. Buff-throated Sunbird males have a distinctive buff throat patch and more extensive metallic coloration elsewhere; look for this contrast in good light.
2. Female and immature bill shape: Cameroon Sunbird females and immatures have a noticeably shorter, less curved bill than Buff-throated Sunbird, which typically has a longer, decurved bill. This is especially useful when plumage is dull.
3. Juvenile/immature underparts: Juvenile Cameroon Sunbirds are dull brown or grey above and below, with a bright yellow belly and steel-blue (not purplish-blue) throat and breast. Immatures show a greenish head gloss and a metallic blue that extends farther down the breast. Use these marks for birds lacking full adult plumage.
4. Female plumage: Cameroon Sunbird females are olive-brown above with yellow-tinged, dull underparts and lack pectoral tufts. Buff-throated Sunbird females are generally less vibrant but specific differences are subtle; rely more on bill shape and structure.
5. Eyering: Adult Cameroon Sunbirds have a bright, pale blue eyering, which may be visible at close range and is not described for Buff-throated Sunbird.
6. Habitat context: In montane forest above 1000 m, especially in Cameroon, Nigeria, or Bioko, Cameroon Sunbird is much more likely. In lowland or secondary growth, Buff-throated Sunbird predominates.
7. Geographic overlap: Both species occur in Cameroon and Nigeria, so range alone is not diagnostic; always check habitat and elevation.
8. Bill color: Both species have black bills and legs, so this is not a separator.
9. Iris color: Cameroon Sunbird has a dark brown iris, which is not described for Buff-throated Sunbird; this is rarely useful in the field.
10. Sexual dimorphism: Cameroon Sunbird males are much more vibrant than females, with clear steel-blue and olive-green contrasts. Females are duller and can be confused with Buff-throated Sunbird females, so structural and habitat clues become more important.
11. Flight views: No distinctive upperwing or flight pattern marks are described for either species, so rely on structure and overall coloration.
12. Perched views: Focus on breast color, eyering, and bill shape for perched birds, especially in good light.
13. Seasonal variation: No strong seasonal plumage changes are described; age and sex differences are more important.
14. Vocalizations: Not described in the available notes; do not rely on voice for separation unless local knowledge is available.
15. Common pitfalls: Immature and female sunbirds of both species can appear very similar; always combine multiple field marks (bill shape, habitat, subtle plumage tones) rather than relying on a single feature.

Only Cameroon Sunbird has a documented average mass (11.2 g [wikidata]); Buff-throated Sunbird is likely similar in size, as both are typical small sunbirds, but no direct measurement is available. In the field, size alone is unlikely to be a reliable separator between these two species.

Juvenile and immature Cameroon Sunbirds are duller above and below than adults, with brown or grey replacing metallic areas and a bright yellow belly. Their throat and breast are steel-blue (not deep purplish-blue), and immatures have a darker olive tone with a greenish head gloss and a metallic blue area extending farther down the breast. Females are olive-brown above with yellow-tinged, dull underparts and lack pectoral tufts. Adult males have a metallic steel-blue upper breast with violet reflections, olive-green hindneck and body, and a pale blue eyering. For Buff-throated Sunbird, detailed age-specific plumage is not provided here, but adult males are known to have a buff throat patch and more extensive metallic coloration elsewhere. Female and immature Buff-throated Sunbirds are generally less vibrant, but specific contrasts with Cameroon Sunbird females/immatures are not detailed in these notes. In summary, look for the steel-blue breast and olive-green body on Cameroon Sunbird males, and the buff throat on Buff-throated Sunbird males; for females and immatures, bill shape and subtle plumage tones are more useful.

Both species are nectar feeders and are likely to be seen actively foraging among flowers, often in the canopy or at forest edges. There is no diagnostic behavioral difference noted between these two species in the available sources.

Cameroon Sunbird is restricted to montane forests in Cameroon, Nigeria, and Equatorial Guinea (including Bioko), favoring high-altitude forest environments. Buff-throated Sunbird has a much broader range, occurring in lowland forests, secondary growth, and forest edges across West and Central Africa, including Cameroon and Nigeria. If observed in true montane forest above 1000 m, Cameroon Sunbird is more likely; in lowland or disturbed habitats, Buff-throated Sunbird is the default.