Red-throated Thrush vs Naumann's Thrush

In short

The most reliable field mark between Red-throated Thrush and Naumann's Thrush is the color and distribution of reddish tones: Red-throated Thrush males have a distinct red throat (females and immatures lack this, but show streaked underparts), while Naumann's Thrush shows reddish on the face, breast, flanks, and rump, with a pale brown back and head. Both species have reddish underwings, but Naumann's Thrush is more extensively rufous below and on the rump. Immature and female Red-throated Thrushes can be especially tricky, as they lack the red throat and instead show streaked underparts, so careful attention to the overall pattern and distribution of reddish coloration is key. Structure and size are similar, so plumage is the primary separator in the field.

Identification tips

1. Red throat in adult males: Only Red-throated Thrush males show a clear red throat patch. If you see a bird with a red throat, it's a male Red-throated Thrush. This mark is absent in Naumann's Thrush of any age or sex.
2. Reddish face, breast, flanks, and rump in Naumann's: Naumann's Thrush shows reddish on the face, breast, flanks, and rump, with a pale brown back and head. If the reddish is broadly distributed and not just on the throat, favor Naumann's.
3. Plain grey back vs pale brown back: Red-throated Thrush has a plain grey back, while Naumann's has a pale brown back and head. This can help in good light, especially on perched birds.
4. Reddish underwings in both: Both species show reddish underwings in flight, so this is not a separator.
5. Streaked underparts in female/immature Red-throated: Female and immature Red-throated Thrushes lack the red throat but have black-streaked underparts. Naumann's immatures have weaker patterning and more extensive reddish below.
6. White belly and undertail in Naumann's: Naumann's Thrush has a white belly and undertail, contrasting with the reddish flanks and rump. Red-throated Thrush does not show this strong contrast.
7. Reddish rump in Naumann's: Reddish on the rump is a feature of Naumann's Thrush, not Red-throated.
8. Supercilium: Naumann's Thrush has a pale supercilium (eyebrow), which can be a subtle but helpful mark if visible.
9. No strong structural differences: Both are similar in size and build; do not rely on jizz or structure for separation.
10. Age-related pitfalls: Immature and female Red-throated Thrushes can be confused with Naumann's due to lack of red throat and presence of streaking. Always check the distribution of reddish and the presence/absence of streaks.
11. Seasonal context: Both species are rare vagrants in Europe; context does not help much unless you are in their core breeding or wintering ranges.
12. Flock composition: Naumann's may be seen in small flocks in winter, but this is not a strong separator.
13. Habitat overlap: Both use similar habitats, so do not use habitat as a primary field mark.
14. Voice not diagnostic: No vocal differences are described for field separation.
15. When in doubt, focus on the throat and extent of reddish below: The combination of throat color (red in male Red-throated only), extent of reddish on the underparts and rump (more in Naumann's), and presence of streaking (female/immature Red-throated) are the most reliable clues.

Size

Both species are medium-sized thrushes and are similar in overall structure and mass. Red-throated Thrush is described as a large thrush, while Naumann's Thrush is called medium-sized but stocky, reminiscent of a small fieldfare. In practice, size is not a reliable separator between these two, especially at a distance or in mixed flocks.

Plumage

• Immatures and Females: Red-throated Thrush females and young birds lack the red throat and instead have black-streaked underparts. Naumann's Thrush immatures have a weaker patterning than adults but still show reddish on the face, breast, flanks, and rump, with a pale brown back and head. Both have reddish underwings, but Naumann's is more extensively rufous below and on the rump.
• Adult Males: Red-throated Thrush males have a clear red throat (the namesake feature), plain grey back, and reddish underwings. Naumann's Thrush males lack a red throat but have reddish on the face, breast, flanks, and rump, with a pale brown back and head, and white belly and undertail. The reddish is more broadly distributed in Naumann's, while in Red-throated it's concentrated on the throat (males) or absent (females/immatures).
• In Flight: Both show reddish underwings, so this is not a separator. Look for the extent of reddish on the rump and flanks (more in Naumann's) and the presence or absence of a red throat (only Red-throated male).

Behaviour

Both species are migratory and may be seen in small flocks during migration or winter. Naumann's Thrush is noted for sometimes forming small flocks in winter. There are no strong behavioral differences noted for field separation.

Habitat

Both species breed in open woodland areas across Siberia and Manchuria, with overlapping ranges. Both are rare vagrants to western Europe. Habitat is not a reliable separator in the field, especially on migration or in wintering areas.

Voice

No diagnostic vocal differences are described between these two species in the provided notes. Both may have songs reminiscent of other thrushes, but these are not detailed or contrasted here.