Phylloscopus collybita - Spring

AGE – BEST CRITERIA:

Individual differences in wear and moult makes ageing problematic at times. Moult contrasts are often present in MC, GC, tail and TT in both age classes, and should be examined carefully. Iris is of little or no help due to the fact that most 2cy have developed a slightly warmer colour (as well as individual variation in 3cy+).

2cy:

Outermost GC are still juvenile (in Scandinavia it is very rare to find individuals that have moulted all GC). Juvenile GC are generally worn, faded and freyed, in contrast to inner GC that may be either pre-breeding (rather fresh) or post-juvenile (intermediately worn) or both.
The RR are assessed in the same way – presence of any juvenile RR (often extremely worn) proves the bird as 2cy, while presence of pre-breeding and post-breeding/post-juvenile (which can not be separated) does not prove any age.
TT are assessed according to the same principle. A few 2cy also show a moulted inner SS (from either of the post-juvenile or the pre-breeding moult).
The still juvenile PC and PP in 2cy have become more worn (sometimes considerably so) and freyed than in 3cy+, but differences are not always obvious.

3cy+:

Moult contrasts may be found in both GC, TT and RR, but always consist of pre-breeding and post-breeding generations only – never juvenile.
The post-breeding PC and PP in 3cy+ have become slighty or moderatly worn, in general fresher than in 2cy.

A word of caution: Note that Chiffchaffs may spend their winters in N Europe as well as in Sub-Saharan Africa, and the choice of wintering grounds will have deep impact on the state of wear in single birds in spring.

2cy March. LC, MC and GC6 + GC8-9 are pre-breeding, while rest of GC (as well as PC) are juvenile. Note that, on this early date, the juvenile GC are still only moderately worn. [SN9770]

2cy June. LC and MC seem to be predominantly pre-breeding while GC5-9 are post-juvenile and GC1-4 (and PC) are juvenile. Note that, by late spring, the juvenile GC have become considerably worn. [SS3013]

2cy April. LC and MC seem to be a mixture of post-juvenile and pre-breeding feathers, while GC9 is pre-breeding and GC1-8 are juvenile. [SN9916]

2cy April. LC and MC are pre-breeding while the GC actually contains three generations of feathers: GC9 is pre-breeding, GC7-8 are post-juvenile and GC2-6 are juvenile. Oddly, it seems that GC1 has also been moulted during the winter but, considering that the same goes for the inner two PC, this may perhaps more likely be explained by replacment after an accident, rather than true moult. [SN9944]

3cy+ May. LC and MC seem to contain both pre-breeding and post-breeding feathers. GC9 is pre-breeding and GC1-8 (and PC) are post-breeding. [SS3003]

3cy+ April. LC may perhaps be pre-breeding, but rest of wing (MC, all GC and PC) is post-breeding. Note the difference in wear in the post-breeding GC in this bird compared to the bird to the left (one month later). [SN9929]

2cy April. Whole tail juvenile (and much worn) apart from both R1 which are pre-breeding. [SN9905]

2cy May. The whole tail is pre-breeding (and fresh) apart from the much worn left R2 which is juvenile. [SN9954]

2cy April. A predominantly post-juvenile tail, but with pre-breeding R1 (both) and left R2-3. Note that no juvenile R is present and, hence, this tail does not reveal the age of the bird (the same tail, albeit with post-breeding instead of post-juvenile feathers) may also be found in 3cy+. [SN9904]

2cy April. An interesting tail which actually contains three generations of RR: both R1 are juvenile, left R5 is pre-breeding and rest of the tail is post-juvenile. [SN9899]

3cy+ May. A uniform post-breeding tail. Note that this tail (as well as the one to the right) does not help the ageing process - the only useful tails are the ones that contain juvenile feathers, proving the bird as 2cy. [SN9980]

3cy+ June. A predominantly post-breeding tail, but with pre-breeding R4 (both) and right R5. [SS3011]

2cy May showing a uniform set of juvenile TT. Note however that, in spring, 2cy Chiffchaffs may show TT of any of the three generations (juvenile, post-juvenile and/or pre-breeding). However, the only TT helpful in the ageing process are juvenile ones (proving the bird as 2cy). [SN9981]

2cy April. A uniform set of post-juvenile TT. [SN9900]

2cy April showing a uniform set of pre-breeding TT (as well as a prebreeding S6). [SN9905]

2cy May. The two longer TT are pre-breeding while the short one most likely is post-juvenile. [SN9951]

3cy+ April. The central T is pre-breeding while the longest (and probably also the shortest) are post-breeding. [SN9938]

3cy+ June, showing a uniform set of post-breeding TT. Note the increasing wear during breeding period in late spring/early summer. At a first glance, the TT may appear older than the SS, but careful study of the feather tips shows that they are all of the same generation (the heavier wear in the TT is because those feathers are more exposed/less protected in the closed wing). [SS3011]

3cy+ April showing a uniform set of post-breeding TT. The feathers may appear surpringsly fresh (indicating pre-breeding generation) but note that they are from the same generation as the SS, which are also unusually fresh in this individual. It is likely that this bird have spent it's winter in a dark and moisty environment (C or N Europe?). [SN9903]

3cy+ April showing a uniform set of pre-breeding TT. Intrestingly, these TT appear rather similar to the ones to the left. Careful study will, however, reveal that they are from a fresher generation than the inner SS, and therefore must be pre-breeding. [SN9937]

Phylloscopus collybita - spring