ハチマキヒタキモドキ 対 キンカムリブチタイランチョウ

The most reliable field mark between Three-striped Flycatcher and Golden-crowned Flycatcher is size: Golden-crowned is much larger and bulkier, with a stouter bill and longer body. Three-striped Flycatcher is notably smaller, slimmer, and more delicate overall. In plumage, Three-striped shows a continuous white supercilium that wraps around the nape and a clean, bright yellow underside, while Golden-crowned has a hidden yellow crown patch (rarely visible), a white supercilium that does not wrap the nape, and buffy-yellow underparts with olive streaking on the breast. Both species have dusky wings and tails with pale or rufous edges, but Golden-crowned's wings and tail show more rufous tones. Structure and overall jizz are often as useful as plumage for separating these two, especially in poor light or at a distance.

1. Size is the fastest separator: Golden-crowned Flycatcher is much larger and bulkier than Three-striped. Use this when you have a good sense of scale or see both species in the same area; beware of lone birds in poor conditions.
2. Bill shape: Three-striped has a long, thin, almost delicate blackish bill; Golden-crowned's bill is noticeably stouter and more robust. This is best seen in profile or when the bird is calling.
3. Supercilium pattern: Three-striped shows a striking white supercilium that wraps from the lores around the nape, creating a 'halo' effect. Golden-crowned's supercilium is long but does not wrap the nape—look for this difference in perched birds.
4. Crown color: Three-striped has a dusky brown crown with no yellow patch. Golden-crowned's crown is brownish gray to dusky, but with a hidden golden-yellow patch in the center, rarely visible unless the feathers are raised.
5. Face pattern: Three-striped's face is dusky brown, blending into the crown, with the white supercilium standing out. Golden-crowned's face is mostly grayish dusky with a long white supercilium but lacks the wraparound effect.
6. Upperparts: Both are olive above, but Three-striped is paler overall. Golden-crowned's rump and uppertail coverts are more greenish olive, sometimes with cinnamon or buffy edges—subtle but visible in good light.
7. Wing and tail edging: Three-striped's wings are dusky with faint pale tips/edges, never rufous. Golden-crowned's wings and tail have thin rufous to tawny-buff edges, especially on the coverts and flight feathers; look for a warmer, more colorful impression in Golden-crowned.
8. Underparts color: Three-striped is bright lemon-yellow below with a faint olive tinge on the breast (or none in some subspecies). Golden-crowned is pale yellow below, but the chin is white, the throat is pale buffy, and the breast is buffy yellow with a cloudy suffusion of pale grayish olive and olive streaks on the sides—giving a more patterned and less clean look.
9. Breast pattern: Only Golden-crowned shows olive streaks on the sides of the breast and a cloudy olive suffusion in the center; Three-striped's breast is much cleaner.
10. Tail color: Three-striped's tail is dusky with little contrast; Golden-crowned's tail is dusky with some rufous edges, especially visible in good light or when fanned.
11. Leg and iris color: Both have blackish legs and dark irises; not useful for separation.
12. Sexes: Both species are sexually monomorphic—do not use sex as a separator.
13. Juvenile/immature marks: No strong age-specific wing or tail panels are described for either species; focus on overall structure and plumage.
14. Habitat and range: Both can occur in the same countries, but Three-striped is more widespread. Do not rely on range alone for separation in areas of overlap.
15. Behavior/jizz: Golden-crowned will appear heavier, slower, and more robust in flight or when perched; Three-striped is more petite and agile. Use this in combination with plumage marks for best results.

Golden-crowned Flycatcher is substantially larger (18.5–22 cm) and heavier (37–40 g) than Three-striped Flycatcher (13.5–14.5 cm; weight not given but much lighter by proportion) [wikipedia]. The difference is obvious in the field: Golden-crowned appears robust and big-headed, with a thick, strong bill, while Three-striped looks petite, slim, and fine-billed. If seen together, size alone is usually diagnostic.

• Juvenile/immature wing pattern: No age-specific wing panel or contrasting marks are described for either species; both have dusky wings with pale or rufous edging, but Golden-crowned's are more rufous/tawny-buff, while Three-striped's are faintly paler-tipped or edged, never rufous. This difference is subtle and best seen in good light.
• Head pattern: Three-striped Flycatcher has a distinctive white supercilium that starts at the lores and wraps around the nape, creating a strong 'three-striped' effect with the dusky crown and face. Golden-crowned has a long white supercilium but it does not wrap the nape; its crown is brownish gray to dusky with a hidden golden-yellow patch (usually not visible in the field).
• Upperparts: Both are olive above, but Three-striped is paler olive, while Golden-crowned is dull olive with a greenish olive rump and uppertail coverts, sometimes with cinnamon/buffy edges.
• Wings and tail: Three-striped has dusky wings with faint pale tips/edges and a dusky tail; Golden-crowned's wings and tail are dusky with thin rufous/tawny-buff edges, especially on the coverts and flight feathers, and some rufous on the tail feathers.
• Underparts: Three-striped is bright lemon-yellow below with only a faint olive tinge on the breast (or none in some subspecies); Golden-crowned is pale yellow below, but the chin is white, the throat is pale buffy, the breast is buffy yellow with a cloudy suffusion of pale grayish olive and olive streaks on the sides. This gives Golden-crowned a more patterned, less clean look below.
• Bill and iris: Three-striped has a long, thin, blackish bill; Golden-crowned's bill is stouter and black. Both have dark irises.

Behavior is not described in detail for either species in the provided notes. Both are typical tyrant flycatchers and may perch conspicuously, but Golden-crowned's larger size and heavier build may give it a more deliberate, less agile appearance compared to the daintier Three-striped. In flight, Golden-crowned will look bulkier and longer-tailed, while Three-striped should appear more compact and lighter.

Both species overlap in Argentina, Bolivia, and Peru, but Three-striped Flycatcher has a much wider range, extending into Brazil, Ecuador, Paraguay, and Venezuela. No habitat preferences are described in the notes, so habitat is not a reliable separator based on this information alone.