AGE – BEST CRITERIA:

Autumn criteria are still applicable, though 2cy are more affected to wear during the winter than ad. Moult contrast present in the wing of 2cy, generally among GC and often between inner GC and TT. Sometimes also among RR and TT, or rarely between TT and inner SS. Ad birds show a uniform plumage without moult contrasts.

2cy:

• Often show moult contrast in GC: Slightly worn post-juv inner GC are denser and often clearly longer and broader than notably worn juv outer GC, edged deeper chestnut-brown, with brown colour of outer vane diffusely bleeding onto shaft of feathers. Juv GC show looser structure with narrower and more sharply offset pale and bleached straw-coloured edges, sometimes fading to whitish near tip. Some birds may have included all GC, and the contrast is then found towards the still juv and worn PC. Word of caution: Amount of black in outer vane increases progressively from inner to outer feathers regardless of generation; note juv-like pattern on ad-type outermost GC (GC1-2), showing narrower brown fringe sharply offset from black centre of the feather, not reaching shaft. Fringe of ad-type GC1 typically paler brown than adjacent feathers, creating false contrast.
• Juv CC shorter and more frayed in tip than ad-type, with warm brown or straw-coloured fringe, similar to juvenile GC.
• Single TT may have been included in the post-juv moult. Post-juv TT are slightly worn, though original contour of feathers often better preserved, showing broader shape, deeper brown outer vanes and darker blackish inner vanes than on notably worn juv ones. The latter typically show strongly bleached straw-coloured fringes to outer vanes and duller brownish centres, commonly with wear eating into most exposed pale areas creating broken feather contours already by mid-April. Juv TT may also contrast well to moulted post-juv inner GC.
• In general, juv PC are less dense, narrower and more pointed than ad-type. By spring, most birds show significantly more wear than ad, especially in tips and outer vanes of outer PC, with pale fringes sometimes almost completely worn off. Typically, juvenile feathers show dull blackish centres with bleached pale buffish or off-white fringes to outer PC, whereas ad-type are a deeper glossy black, with fresher, whiter fringes of outer PC sometimes corresponding with white colour on outer vanes of inner PP, though often edged warmer buff. Fringes of inner PC less worn, warmer brown and thus more similar in both juv and ad-type. However, due to variation in both age-groups, PC are often difficult to use for ageing.
• Juv PP are generally heavily worn and bleached, with exposed part of tips a faded, dull brown.
• Juv RR are slightly narrower, more pointed, and generally more worn than ad ones, typically showing completely worn-down white fringes at tips, causing blackish centres to reach edges of feathers. Some individuals have replaced single or several RR and then exhibit moult contrasts. Recently grown fresh ad-type RR (presumably caused by accidental loss and replacement rather than a scheduled moult) are not uncommon irrespective of age class.

3cy+:

• Uniform plumage lacking any moult contrasts.
• Whole wing and tail slightly worn, but still in better condition than juvenile feathers in 2cy, with denser structure and better gloss. Tertials, tips of outer PP and fringes to outer PC generally significantly less worn and bleached than in 2cy.
• CC longer and denser, with colder, chestnut or rufous fringe, similar to adult-type GC.
• Tips of RR slightly blunter and broader, with white fringes on average less worn and centres a deeper black, less faded and bleached than juvenile feathers.