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Juvenile birds have brightly notched tertials, scapulars and GCs, giving an overall spangled appearance which is uniform across these three feather tracts (all feathers being of the same generation). Juvenile birds have shorter bills initially, but these are typically fully grown by late August. Juveniles show streaking on their breast and flanks until around late December, when they can be showing the chevroned breast and flanks of 1w and winter adult birds.
Juvenile Curlew typically do not moult all that many feathers; only some inner (ie., the largest) tertials and smaller coverts, occasionally some scapulars, are moulted. In consequence, juveniles will be looking very worn by Dec/Jan, with tertials, GCs and lower scapulars in particular appearing faded and notched (lanceolated). In contrast, adults will have finished their complete post-breeding by Nov, and so the presence, by Dec/Jan, of worn and notched feathers will be indicative of a 1w bird. The challenge will be to tell these worn feathers, which will look faded, from the faded and barred non-breeding feathers of adult birds.
The mantle feathers of juvenile, 1w and adult birds are fringed, as opposed to notched.
Juvenile and 1w coverts have dark, chocolate-brown centres with buff fringing, contrasting with adult non-breeding coverts which have paler, greyish centres and buff fringing, resulting in a closed wing that appears notably darker than the adult's closed wing.
1w birds will typically display worn and notched tertials, GCs and lower scapulars by Dec/Jan. A minority of juvenile Curlew will replace some or all tertials and some GCs and lower scapulars with adult non-breeding feathers, with the result that a contrast can be seen between the juvenile notched/dogtoothed tertials and scapulars and the faded, barred adult-type feathers.
By late December, most 1w birds will have replaced the streaked juvenile feathers on their breast an flanks with newly moulted-in adult-type chevroning.
1w coverts, like juvenile coverts, have dark, chocolate-brown centres with buff fringing, contrasting with adult non-breeding coverts which have paler, greyish centres and buff fringing, resulting in a closed wing that appears notably darker than the adult's closed wing.
2cy spring birds acquire a variable number of adult breeding-type scapulars and tertials, which will first be observable around late-February to early-March, the black and buff colours of which (see Adult breeding, below) will contrast with the browner, more faded-looking juvenile wing coverts and any unmoulted juvenile tertials and upperpart feathers.
Adult non-breeding birds will have finished their complete post-breeding moult by November. Tertials, and scapulars will appear faded and barred, contrasting with juvenile type notched/dogtoothed feathers. The challenge by Dec/Jan will be to tell adult non-breeding feathers (faded and barred) from juvenile feathers (faded and notched). Winter adult birds have chevroned breasts and flanks, unlike the streaking of juvenile and early-winter 1w birds.
Unlike juvenile and 1w wing coverts, which have dark, chocolate-brown centres with buff fringing, the adult non-breeding coverts have paler, greyish centres and broad whitish-buff fringes, resulting in a closed wing that appears notably lighter and more buff in colour than the darker closed wing of juveniles and 1w birds.
Note that Curlew breed only in their third calendar year, and so 2cy birds will exhibit plumages that are intermediate between non-breeding and adult breeding.
Adult breeding birds transition, in a spring partial pre-breeding moult, from the overall grey of their non-breeding plumage to upperparts and tertials with blackish centres and strikingly buff (in some cases, greyish) fringes, which contrast with the retained, faded greyish non-breeding- type wing coverts.
Curlew juvenile, told by dogtooth pattern on tertials, GCs and scapulars, and uniformity of tone and patterning across all feather tracts; also wing coverts with dark centres and buff fringing. The short bill will be fully grown by late August.
Curlew 1w or 2cy, showing contrast between moulted-in adult non-breeding tertials (barred) and retained juvenile tertials (x2, both worn and notched). This individual has replaced several scapulars with adult non-breeding (barred). The wing coverts are juvenile (dark centres, worn and notched fringes) as are the feathers on the breast and flanks (streaked, not chevroned). The extent of wear suggests that this could be a 2cy winter bird. Image: Matthias Schaf.
Curlew adult winter bird in non-breeding plumage. Note the overall uniformity (faded, buff-grey), and the faded barred tertials and GCs (contrast the dogtoothed feathers of the juvenile in the first photo). The wing coverts have narrow centres and extensive buff fringing, unlike juvenile coverts. Image: Kinan Echtay.
Curlew adult winter bird in non-breeding plumage.
Curlew in mainly adult non-breeding plumage, acquiring some breeding-type scapulars, median coverts and (just visible) mantle feathers with darker centres and brighter buff fringes, contrasting with the worn grey fringes of the non-breeding feathers. Photo taken in Spring. Image: Terry Whittaker.
Eurasian Curlew in breeding plumage. Note the scapulars, mantle feathers and some smaller coverts with blackish centres and bold buff fringes, also the buffish barring of the tertials. Image: Artur Stankiewicz.
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