Locustella naevia - spring

Common Grasshopper Warbler

AGE – BEST CRITERIA:

Most birds arrive in spring with a uniform plumage due to the complete winter moult. Such birds can not be aged. Other birds are more intriguing:
  • A few birds (perhaps young birds only?), arrive Europe with a few unmoulted, worn, inner PP and outer SS.
  • Individuals with fresh GC and SS and more worn PP and PC are known (perhaps created by differentiated periods of moult during winter?).
Until further research has been presented it is advicable to leave all birds as 2cy+.

2cy+ May. The whole wing is pre-breeding - probably also S4, although it seems like it is slightly older than rest of SS. [CV03622]

2cy+ May. SS and GC1-6 are fresh and newly moulted, in contrast to PP, PC, TT and GC7-10. However, it still seem unlikely that the older part of wing are post-breeding (or even more unlikely, from the former pre-breeding moult), and perhaps this pattern is best explained by differentiated periods of moult during winter? It may be tempting to age such birds as 3cy+, but until further information is presented it is perhaps best left as 2cy+. [CN94349]

2cy+ May. A uniform pre-breeding tail. [CN94349]

2cy+ May. A tail containing weak but detectable differencis in wear, perhaps best explained by differentiated periods of moult during winter? [CV03622]

More Locustella naevia:

Ageing autumn
Moult

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