オオアカゲラ 対 コアカゲラ

The most reliable field mark between White-backed and Lesser Spotted Woodpecker is size: White-backed is much larger and bulkier, while Lesser Spotted is tiny and often overlooked. In flight or perched, note the wing pattern: White-backed shows white bars across the wings and a clean white lower back, while Lesser Spotted has broader, more conspicuous wing bars and a barred lower back. Males of both species have red crowns, but the extent and context differ. Lesser Spotted is typically found high in tree canopies and can be hard to spot, whereas White-backed is more conspicuous on trunks and larger branches. Vocalizations and drumming differ in volume and tone, but these are best used as supporting clues.

1. Size is the quickest check: If the bird looks tiny, sparrow-sized, and delicate, it is Lesser Spotted; if it appears robust and nearly as large as a Great Spotted Woodpecker, it is White-backed. This works for all ages and sexes.
2. Wing pattern in flight or perched: White-backed shows white bars (not spots) across the wings and a clean, unbarred white lower back. Lesser Spotted has broader, more conspicuous bars on the wings and a lower back that is also barred black and white. This is reliable in all plumages.
3. Tail pattern: Lesser Spotted has barred outer tail feathers, visible when the tail is fanned or in flight. White-backed's tail is less distinctly barred.
4. Crown color (sex and age): Adult male White-backed has a red crown; female has a black crown. Lesser Spotted male has a crimson crown with a brown forehead and black supercilium; female has a white crown. Juvenile Lesser Spotted of both sexes can show crimson on the head, so be cautious with young birds.
5. Underparts: Lesser Spotted shows streaks on the flanks; White-backed is cleaner and whiter below.
6. Bill size and shape: White-backed has a proportionally larger, heavier bill suited to excavating larger dead wood. Lesser Spotted's bill is fine and short, matching its small size.
7. Jizz and posture: Lesser Spotted often appears stumpy and almost triangular, especially in flight, and is usually high in the canopy. White-backed is bulkier and more likely to be seen lower on trunks or large branches.
8. Habitat context: If the bird is in a mature, undisturbed broad-leaved forest with lots of large dead wood, White-backed is more likely. If in a park, edge, or mixed woodland with thin dead branches high in the canopy, suspect Lesser Spotted.
9. Vocalizations: White-backed's drumming is loud and forceful; its calls are 'kiuk' and 'kweek.' Lesser Spotted gives a repeated 'keek' and a lighter, vibrating rattle when drumming. Use these as supporting clues, especially if the bird is not seen well.
10. Behavior: Lesser Spotted is often overlooked due to its small size and tendency to forage high in trees. White-backed is more conspicuous and less likely to be missed if present.
11. Seasonal and age pitfalls: Both species' juveniles can show red on the crown, so do not rely solely on head color in young birds. Use wing and back pattern as the primary check.
12. Confusion risk: Both can be confused with Great Spotted Woodpecker, but White-backed is closer in size and structure to that species, while Lesser Spotted is much smaller and more delicate.
13. No marked seasonal change: Both species retain similar plumage year-round, so seasonal variation is not a major pitfall.
14. Population context: Lesser Spotted is declining in many areas and is much less likely to be encountered than White-backed in some regions, but local abundance varies [ebird].
15. Nest hole clues: Lesser Spotted's nest holes are smaller (2.5–5 cm diameter) and higher up (often 10–20 m), while White-backed's are larger and lower, but this is rarely useful in the field unless nest excavation is observed.

White-backed Woodpecker is the largest of the spotted woodpeckers in the western Palearctic, measuring 24–26 cm in length with a wingspan of 38–40 cm [wikipedia]. In contrast, Lesser Spotted Woodpecker is the smallest European woodpecker, only 14–16.5 cm long with a wingspan of 24–29 cm and weighing around 20 g [wikipedia]. The difference is dramatic: Lesser Spotted is less than two-thirds the length and much lighter, appearing delicate and sparrow-sized, while White-backed is robust and closer in size to Great Spotted Woodpecker.

• Juvenile/immature birds: Both species' young can show some red on the crown, but Lesser Spotted juveniles of both sexes have more or less crimson on the head, while in White-backed, only the male shows a red crown (female is black-crowned).
• Wing pattern: White-backed Woodpecker (all ages) has white bars across the wings (not spots), and a striking white lower back. Lesser Spotted Woodpecker shows broader, more conspicuous bars on the wings, and the lower back is also barred black and white, not clean white. The outer tail feathers of Lesser Spotted are barred as well.
• Adult males: Both have red crowns, but in Lesser Spotted, the red is limited to the crown with a brown forehead and black supercilium; in White-backed, the red is more extensive on the crown.
• Adult females: White-backed female has a black crown; Lesser Spotted female has a white crown.
• Underparts: Both have pale underparts, but Lesser Spotted shows streaks on the flanks, while White-backed is cleaner below.
• Seasonal change: Neither species shows marked seasonal changes in plumage.

Lesser Spotted Woodpecker spends most of its time high in the canopy, often at the tops of tall trees, and is easily overlooked due to its small size and secretive habits. Its flight is described as stumpy and almost triangular, bounding from tree to tree. White-backed Woodpecker is more likely to be seen on trunks or large branches and is generally more conspicuous due to its size and bolder behavior. Both species drum and forage for insects in dead wood, but Lesser Spotted often targets thin dead branches, while White-backed is more associated with larger decaying wood.

Both species are woodland birds, but Lesser Spotted Woodpecker is more often found in parks and mixed woodlands, especially where there are tall trees and dead branches. It is highly dependent on decaying wood in the canopy and is sensitive to the removal of dead trees. White-backed Woodpecker prefers mature, often broad-leaved forests with abundant dead wood, especially in less disturbed areas. While their habitats can overlap, White-backed is generally found in larger, older forests, whereas Lesser Spotted can occur in smaller woodlots and urban parks if suitable dead wood is present.

White-backed Woodpecker's drumming is very loud and forceful; its calls include a soft 'kiuk' and a longer 'kweek.' Lesser Spotted Woodpecker gives a repeated 'keek,' which is loud for its size, and its drumming is a vibrating rattle that, with experience, can be distinguished from the deeper, more resonant drumming of larger species like White-backed. Lesser Spotted's vocalizations are often the first clue to its presence, as it is otherwise inconspicuous.