キンイロコウヨウジャク 対 シュイロマシコ

The most reliable field mark is the breeding male Asian Golden Weaver’s bright yellow plumage with a black face mask and strong black bill, which is never matched by the Scarlet Finch. However, outside the breeding season or in females and immatures, Asian Golden Weavers become much duller and can be confused with other yellowish passerines, but still show a noticeably thicker bill than the Scarlet Finch. Scarlet Finches, in contrast, are never yellow: adult males are deep scarlet red, while females and immatures are olive or brownish, lacking any yellow tones. Bill shape and color, as well as overall structure, also help separate these two, especially when plumage is ambiguous. Habitat and range overlap only in parts of Southeast Asia, but context can help in ambiguous cases.

1. Breeding male Asian Golden Weaver: Look for bright yellow plumage with a bold black face mask and strong black bill. Scarlet Finch never shows this combination.
2. Non-breeding/female/immature Asian Golden Weaver: Duller yellowish-brown, but still with a noticeably thick, conical bill. Scarlet Finch of any age or sex never shows yellow tones or a black mask.
3. Scarlet Finch adult male: Deep scarlet red overall with black wings and tail, never yellow or masked. Asian Golden Weaver never shows red plumage.
4. Scarlet Finch female/immature: Olive or brownish, lacking yellow or black mask, with a paler, less robust bill than the weaver. If you see a brownish bird with a thick, dark bill, suspect weaver; if the bill is paler and the bird is more compact, suspect finch.
5. Bill shape and color: Asian Golden Weaver has a thick, strong, black bill (especially in breeding males), while Scarlet Finch has a less massive, paler bill.
6. Structure: Weavers are longer and slimmer, with a more elongated body and tail. Scarlet Finch is more compact and chunky.
7. Behavior: Weavers are often seen in colonies, especially near water, and may be observed weaving nests. Scarlet Finches are more solitary or in small groups, foraging in trees or bushes.
8. Habitat: If the bird is in open, wet, grassy or agricultural land, especially in a colony, Asian Golden Weaver is more likely. If in forested or shrubby hills, especially at higher elevation, Scarlet Finch is more likely.
9. Geographic context: In the Himalayas or adjacent hills, Scarlet Finch is expected; in lowland Southeast Asia, especially in wetlands, Asian Golden Weaver is more likely.
10. No distinctive juvenile wing patterns: Neither species shows a unique upperwing pattern in flight for juveniles or immatures, so rely on bill shape and overall color.
11. Plumage pitfalls: Non-breeding and immature weavers can look drab and may be confused with other yellowish passerines, but the thick bill is a giveaway. Scarlet Finch never shows yellow or a black mask.
12. Sex/season: Only breeding male Asian Golden Weaver is bright yellow with a black mask; all other ages and sexes are duller. Scarlet Finch males are always red, females/immatures olive or brownish.
13. Colony vs solitary: Large groups in reeds or fields point to weaver; single or small groups in trees/shrubs point to finch.
14. Nest observation: If you see intricate woven nests, you are looking at weavers, not finches.
15. Voice: Not diagnostic with current notes; do not rely on calls or songs for separation.

Scarlet Finch is a heavier bird (body mass ~40g [wikidata]), while Asian Golden Weaver is medium-sized for a weaver but likely lighter (exact mass not given). The weaver averages about 22 cm in length [wikipedia], which is long for a weaver and may overlap with the Scarlet Finch, but the finch is more robust and compact. The weaver’s bill is thicker and more conical, especially obvious in side view. Scarlet Finch is more finch-like in build, with a less massive bill and a more compact, chunky body.

Breeding male Asian Golden Weavers are unmistakable: bright yellow overall with a black face mask and strong black bill. Non-breeding males, females, and young weavers are much duller, yellowish-brown, and can be confused with other weavers, but still have a thicker bill than finches. Scarlet Finch males are deep scarlet red with black wings and tail, never yellow or masked; females and immatures are olive or brownish, lacking any yellow or black mask, and have a paler, less robust bill. There are no notes of distinctive juvenile or immature upperwing patterns for either species. Subspecies of Asian Golden Weaver may show more greenish-yellow on the mantle and more raw sienna on the upper breast, but this does not overlap with the Scarlet Finch’s color palette. In all ages and sexes, Scarlet Finch never shows the yellow or black mask of the weaver, and Asian Golden Weaver never shows the deep red of the finch.

Asian Golden Weavers are often seen in colonies, especially in wetland or agricultural areas, and may be observed weaving nests in reeds or grasses. They are more likely to be seen in open, lowland, wet habitats. Scarlet Finches are typically found singly or in small groups, foraging in trees or bushes, and are less likely to be seen in open wetlands. Their behavior is more typical of forest or edge finches, often perching upright and moving through foliage.

Asian Golden Weaver is found in seasonally wet or flooded lowland grasslands, swamps, and arable land, mostly in Southeast Asia (Cambodia, Indonesia, Laos, Myanmar, Thailand, Vietnam) [wikipedia]. Scarlet Finch is a bird of the Himalayas and adjacent hills, sometimes wintering further south into Southeast Asia, but is generally found in forested or shrubby habitats, often at higher elevations. Overlap may occur in northern Thailand and adjacent regions, but habitat preferences differ: weavers in open wetlands and fields, finches in wooded or shrubby hills.