アオガラ 対 テネリフェアオガラ

The most reliable field mark between Eurasian Blue Tit and African Blue Tit is the facial pattern: Eurasian Blue Tit shows a blue crown with a dark blue line through the eye encircling the white cheeks, while African Blue Tit (especially the nominate race) features a white forehead and supercilium extending to the nape, with a deep glossy blue crown and blackish neck. Both are small, blue-and-yellow tits, but Eurasian Blue Tit is more intensely colored and has a distinctive dark line down the yellow underparts, whereas African Blue Tit’s facial white is more extensive and its blue crown is glossier. Juvenile Eurasian Blue Tits are yellower and less contrasting than adults, which can cause confusion with African Blue Tit, but the facial pattern remains a key separator. Structural differences are subtle, but Eurasian Blue Tit is slightly smaller and lighter on average.

1. Facial pattern is the most reliable mark: Eurasian Blue Tit shows a blue crown with a dark blue line through the eye that encircles the white cheek and chin, forming a distinctive mask; African Blue Tit (nominate) has a white forehead and supercilium extending to the nape, with a deep glossy blue crown and blackish neck, lacking the full encircling dark line.
2. Crown color and gloss: Eurasian Blue Tit’s crown is intensely blue but not as glossy as African Blue Tit’s deep glossy blue crown. Under UV, male Eurasian Blue Tit crowns are brighter, but this is not visible to humans.
3. Extent of facial white: African Blue Tit has more extensive white on the forehead and supercilium, forming a broad white area above the eye, while Eurasian Blue Tit’s white is mostly confined to the cheek and chin.
4. Neck color: African Blue Tit shows a blackish neck, contrasting with the blue crown and white supercilium; Eurasian Blue Tit’s nape is blue, blending into the crown.
5. Underparts: Eurasian Blue Tit has sulphur-yellow underparts with a dark line down the abdomen, especially in adults; African Blue Tit’s underparts are yellow but lack the strong dark belly line.
6. Back color: Eurasian Blue Tit’s back is yellowish-green, while African Blue Tit’s back is blue, but this is subtle and variable.
7. Juvenile confusion: Juvenile Eurasian Blue Tits are yellower and less contrasting, but still show the blue crown and dark eye-line; African Blue Tit juveniles are not described in detail, but the facial white and blue crown should remain distinctive.
8. Wing and tail: Both species have blue wings and tails; no distinctive wing pattern differences are described for any age.
9. Bill and structure: Both are compact and sharp-billed; bill size and shape are not useful in separation.
10. Behavior: Foraging style is similar and not diagnostic; both are agile and often hang upside-down.
11. Habitat and range: Use location as a strong clue—Eurasian Blue Tit in Europe/Asia, African Blue Tit in North Africa, Canary Islands, Pantelleria.
12. Sex and season: Sexes are similar in both species; seasonal variation is minimal except for juvenile Eurasian Blue Tits being yellower and less contrasting.
13. Size: Eurasian Blue Tit is slightly lighter (11.8 g), but length and structure overlap; do not rely on size in the field.
14. Voice: Not reliably separable by ear based on current information.
15. Pitfalls: The main confusion arises with juvenile Eurasian Blue Tits, which can appear less contrasting and more yellow, but the facial pattern (dark eye-line encircling the cheek) remains a key separator from African Blue Tit’s broad white forehead and supercilium.

Eurasian Blue Tit averages about 11.8 g in body mass and measures 10.5–12 cm in length with a wingspan of 17.5–20 cm. African Blue Tit is similar in length (11–12 cm), but no direct mass data is available; structurally, both are compact and sharp-billed. In the field, size is not a reliable separator, as both species overlap in length and overall proportions. Use plumage and facial pattern rather than size for identification.

Juvenile Eurasian Blue Tits are yellower overall and have less contrast in their plumage, but still show the blue crown and dark eye-line encircling the white cheek, which is lacking in African Blue Tit. Adult Eurasian Blue Tits have an intensely blue crown, a dark blue line through the eye encircling the white cheeks and chin, and a yellowish-green back with sulphur-yellow underparts and a dark line down the belly. African Blue Tit (nominate race) has a white forehead and supercilium extending to the nape, a deep glossy blue crown (less encircled by dark), and a blackish neck. Its back is blue and underparts yellow, but lacks the strong dark belly line of Eurasian Blue Tit. Both species have blue wings and tails, but the facial pattern is the most consistent separator across ages and seasons. Juvenile African Blue Tits are not described in detail, but the facial white and blue crown/glossy contrast should persist.

Both species are active, agile foragers, often seen hanging upside-down to probe for insects and caterpillars. Eurasian Blue Tit is noted for rarely hovering and only occasionally foraging on the ground, preferring to glean from branches and buds. African Blue Tit’s foraging behavior is not described in detail, but as a close relative, it is likely similar. Both visit feeders and exploit a variety of food sources. Behavioral differences are not diagnostic in the field.

Eurasian Blue Tit is widespread and common throughout temperate and subarctic Europe and parts of western Asia, favoring woodlands, gardens, and parks. African Blue Tit is found in northern Africa, Pantelleria (Italy), and the Canary Islands, inhabiting temperate forests. Their ranges do not overlap except potentially in captivity or vagrancy, so location is a strong clue: in mainland Europe, a blue tit is almost certainly Eurasian; in the Canary Islands or North Africa, African Blue Tit is expected. However, habitat structure (woodland, garden, forest) is similar for both.

The African Blue Tit’s song is described as a variable repetition of one or two notes, but no detailed comparison to Eurasian Blue Tit’s vocalizations is available. Both are likely to have typical tit-like calls, but voice is not a reliable separator based on current information.