AGE – BEST CRITERIA:
During spring, ageing is primarily based on assessment of wear in PP, GC and PC. Both age classes may (but most do not) show a moult contrast with pre-breeding inner GC (but many 2cy show the same contrast as during autumn, between post-juvenile and juvenile GC). Moult contrasts may also be present in tail in both age classes. Colour of iris gives no support during spring.
- Juvenile GC and TT are worn and often rather frayed. The pale tips may be worn off (leaving a small gap in the feather tip) or may still show, but now often bleached pale buff.
- A moult contrast (with 1-3 moderatly worn inner post-juvenile GC) may be present in many 2cy birds. Note that Cramp & Perrins (1993) state that a few GC are included in the pre-breeding moult (in both age classes), creating a contrast with fresh inner GC. In our sample this seems rare, but should still be kept in mind.
- The juvenile PC are worn (often considerably) and frayed and often appear darker brownish compared to adult ones.
- If juvenile alula feathers are still present, they are brownish worn, often in contrast to post-juvenile or pre-breeding ones showing less worn greyish tips/edges and a more glossy dark/black centre.
- Tips of PP are generally more more worn and bleached, often appearing more brownish.
- Any juvenile RR still left (often R1) are generally considerably worn, narrower and more pointed than post-juvenile or pre-breeding RR.
- Iris is not useful during spring as it has developed adult colour/pattern.
- PC often in slightly better condition than in 2cy, on average less worn and often a bit paler with slightly greyish edges.
- Alula feathers (post-breeding and/or pre-breeding) show glossy dark centra with less worn greyish tips/edges. No juvenile alula present.
- Tips of PP generally in slightly better condition, being darker and less worn and bleached.
- RR are generally pre-breeding (but single retained post-breeding RR are regularly seen, often R1). Retained post-breeding RR differs from retained juvenile RR (2cy) by being broader and in better condition.
- Iris is not useful during spring.