Green Sandpiper

Often the question posed by ornithologists at the times of migration is: is it a Green Sandpiper or a Common Sandpiper? At a distance and without its voice, this can be a problem to solve through comparison.
The Green Sandpiper is a little bigger, bulkier and slightly longer-legged than the Common Sandpiper. Its plumage is also more contrasting with a darker upperpart and a brighter whitish underpart; this is particularly visible when in flight. From above, the white rump and the white leading edge of the tail feathers, which give its English name, match with the dark back and the barred pattern on the tip of the tail. From below, the dark underside of the wings contrast with the white body (a lesser contrast is visible above and no contrast is visible below in the Common Sandpiper). Among the seven species of sandpipers found in the European area, this is the only one with a dark underside of the wings.
During the spring migration, birds are in the breeding plumage. The Green Sandpiper has a deep blackish brown upperparts with a fine light barring (while the Common Sandpiper has a lighter one with more whitish and beige barring). Its underparts are pure white including the flanks, which also have some dark markings on the anterior edges (the Common Sandpiper has buffy-cream flanks with many dark spots). The head, nape and upper chest are darkly streaked (in the Common Sandpiper, this area is much paler and lacks the 'breastplate' effect). It has a very visible white eye-ring and a feeble whitish supercilium over the black loral area (in the Common Sandpiper, the supercilium is a complete whitish one creating a dark 'cap'). Finally, its legs are greenish (yellow-green in the Common Sandpiper). In the autumn migration, those characteristics remain valid. The upperparts are only slightly more uniform.
The chick is covered in gray-brown down with blackish streaks and whitish underneath.On either side of the head, a black stripe starts at the beak and runs through the eye. The juvenile resembles the adult breeding bird, but the upperparts are spotted with beige rather than whitish and the flanks are all white with no markings in front.