Click here for more species of shorebird and wader in our guide to identification and plumage, or keep reading for Green Sandpiper.
Like several other members of the Tringa genus, the age at first breeding of Green Sandpiper is not known. Some may breed in the second calendar year, others in their third. Bear in mind then, that 2cy birds, if non-breeding, may acquire a plumage that is intermediate between juvenile and full adult breeding/non-breeding.
Green Sandpipers can be seen in the UK when on passage to their Scandinavian breeding grounds in March-April, and again in June to September as juveniles and adults head south to their wintering grounds in southern Europe and Africa. Some overwinter in the UK, usually to be found inland on freshwater pools and ponds.
Juvenile birds have on their wing coverts, tertials and upperparts the whitish edge-spotting that is characteristic of Tringa juveniles. The upperparts are greenish-brown, through at a distance, and particularly as winter progresses, juveniles/1W birds look overall brownish, and the whitish spotting on the tertials, upperparts and exposed coverts turns to buff.
1W birds appear overall brownish, with faded buff spotting on tertials, which will look increasingly notched and lanceolated as winter progresses. Hayman, Marchant & Prater (see Reading) have it that first winter birds are, by November, indistinguishable from winter adults. Personal observations support this to some degree, and the best time to distinguish 1W from older birds is late January onwards.
2cy Spring birds fall broadly into two groups:
(i) those whose partial pre-breeding moult is less advanced, and retain largely juvenile/1W plumage, appearing overall faded brown in colour. Tertials show faded spotting, notching and/or are lanceolated (particularly of course the most exposed inner and middle tertials).
(ii) those whose partial pre-breeding moult is more advanced, and have replaced some mantle and scapulars, and in some cases one tertial, with adult breeding- type feathers, which have a grey-greenish basal colour and are spotted white. These new feathers create in the field a colour contrast between the bird's upperparts (appearing grey-greenish) and its unmoulted wing coverts and tertials which will be overall faded brown.
Note that most 2cy have a partial moult between March and May, replacing a variable number of upperparts and tertials, so that, by April-May, most 2cy birds will look similar in the field.
Adult (3cy+) Spring birds (and maybe some 2cy birds) have a partial pre-breeding moult between December and February, replacing some mantle feathers, most or all scapulars, some or all tertials and some wing coverts, with olive-greenish feathers with white spotting. The spotting, when fresh, is quite striking, particularly on the tertials, in the field from about January onwards, and contrast markedly with the faded buff spotting of younger birds (particularly noticeable on the tertials). The white spotting on the tertials and lower scapulars on 3cy+ birds may in some cases appear bigger and/or whiter than on those 2cy birds which have acquired the same adult breeding-type feathers.
Adults birds in Spring show markedly less contrast between (a) the wing-coverts and (b) renewed upperparts and tertials than 2cy birds, whose wing panels will appear more contrastingly brown.
The pre-breeding moult is complete by March-April, by which time the difference between adult birds (more uniformly olive-greenish overall) and 2cy birds (showing more brown on upperparts and wing panel) should be evident.
Adult (3cy+) Winter birds are similar overall to juvenile birds, with smaller buff spotting on upperparts and tertials which is less distinct than the (fresh) buff spotting on juveniles. The complete post-breeding moult of adults begins on the breeding grounds in June or July, finishing on the wintering grounds in August or September.
Green Sandpiper juvenile. Told by the neat feather tracts characteristic of juvenile shorebirds, and fresh, buff spotting on tertials, wing coverts and scapulars.
Green Sandpiper juvenile, showing neat feather tracts and fresh, buff spotting.
This photo shows the close spotting on the tertials of a juvenile. Contrast with the more spaced spotting on the tertials of older birds.
Juvenile showing lanceolated tertials and faded spotting as early as July.
A 2cy Spring bird of type (i) (explained above): showing mostly juvenile or 1W feathers; no partial pre-breeding moult in evidence.
A 2cy Spring bird of type (ii) (explained above): acquiring adult-type breeding scapulars.
Graham Appleton in his WaderTales blog ascribes this as a juvenile per Richard Chandler, but I am not sure. For me this is a 2cy Spring bird of type (ii) (explained above) with adult breeding-type tertials and some upperparts; not that I am particularly comfortable disagreeing with an authority like Richard Chandler!
A 2cy or adult (3cy+) Spring bird in partial pre-breeding moult, showing new adult-type breeding inner tertial, greater covert and scapulars. The size and brightness/distinctiveness of the white spotting suggests a 2cy rather than a 3cy+ bird.
A 2cy Autumn bird, told by the scruffy feather tracts and the overall faded, brownish look. The extent of the wear suggests that this individual had little or no partial pre-breeding moult in the Spring, unlike most 2cy birds.
Adult (3cy+) in breeding plumage, told by the distinct white spotting on tertials, greater coverts and upperparts. This bird was photographed on its UK wintering ground in early August, after a geo-locator tracked its migration to and from Scandinavia, described here.
Adult (3cy+) in breeding plumage, photographed in the UK in July. Despite the relatively early date (mid-Summer), this bird is already showing very worn tertials (x2) and some wear to its greater coverts.
The extent of this bird's moult - note the missing tertials and inner greater coverts, and the new median coverts - together with the date the photo was taken (May) - suggests a 2cy bird undergoing an unusually extensive pre-breeding moult. More usually, none of the tertials and smaller wing coverts are moulted by 2cy spring birds, which can, however, replace all their scapulars and mantle feathers, as this bird has done. Note the exposed, dark primary coverts, normally concealed on the closed wing by the overlying greater coverts.
Click here for more species of shorebird and wader in our guide to identification and plumage.