Cyanistes caeruleus - Spring - Ringers Digiguide

AGE – BEST CRITERIA:

Autumn criterias are still applicable, though the still juvenile feathers in 2cy are more affected to wear during the winter than adult. Moult contrast is always present in the wing of 2cy, in the vast majority between post-juvenile GC and juvenile PC. Moult contrast may also be present in RR, alula and TT. Adult birds show a uniform plumage.

2cy:

Most birds included all GC in the post-juvenile moult. The fresh and dense GC with rather bright blue outer vanes shows a contrast to the less dense and less brightly coloured juvenile PC. This contrast may be easily detected, but a few may need a more careful study. In some birds (14% at Ottenby) 1-5 outermost GC may be unmoulted juvenile (less dense and less bright blue), and then show a more easily seen contrast to inner post-juvenile GC.
A moult contrast is sometimes seen in the alula, often with CC and the innermost alula moulted post-juvenile contrasting to outer 1-2 juvenile alula. Post-juvenile alula are more dense and bright blue (like the post-juvenile GC) than juveniles ones.
Most birds, c. 70% according to Jenni & Winkler (1994), moulted all TT. Among the rest, the vast majority shows one (the longest) unmoulted juvenile T, while 2-3 retained juvenile TT are rather rare.
C. 70% (according to Jenni & Winkler [1994]) moult R1, and 5% include several RR. Only c. 25% moult no RR at all.
Iris is rather dark olive-grey.

3cy+:

Uniform plumage lacking any moult contrast.
PC denser and with a slightly brighter blue gloss.
Iris usually slightly warmer greyish-brown.

2cy March. Like most Blue Tits, this one shows a uniform set of post-juvenile GC, contrasting to the juvenile PC. [1ET29387]

2cy March, showing the same extent of moult, with exception for the two longest AL that are unmoulted juvenile. [1ES23351]

3cy+ March. Whole wing post-breeding, with no contrast between GC and PC. [1ET29390]

3cy+ March, showing variation. [1ES22354]

2cy March. Note the juvenile PC, less dense and slightly less brightly coloured than post-juvenile GC. Note also the moult contrast in AL with post-juvenile inner two feathers and a juvenile outer (longest) one. [1ES23355]

2cy March, showing variation. Like the PC, also the two longer AL feathers are unmoulted juvenile. [1ES23351]

3cy+ March. Adult post-breeding PC are denser and generally shows a slightly brighter blue gloss. Note the lack of contrast to GC, both concerning colour and structure. [1ET29390]

3cy+ March, showing variation in post-breeding PC. [1ES22354]

2cy (male) March. Most 2cy, like this one, included both R1 in the post-juvenile moult, but a few are more (or less) advanced. Note the contrast between post-juvenile R1 (more fresh, dense, blunt-tipped and slightly brighter blue) and the remaining juvenile RR. [1ES24480]

2cy March, showing a full set of juvenile RR, separable from the post-breeding RR of adult by a pointed shape to the tips as well as more pronounced wear. [1ES24467]

3cy+ March. A uniform post-breeding tail. Note the high quality and blunt-tipped feathers. [1ES23352]

3cy+ March, showing variation of post-breeding RR. [1ES24475]

2cy March. Most 2cy includes all TT in the post-juvenile moult. But a portion of the young birds shows a moult contrast, like this one, with the longest T being unmoulted juvenile. Note the more worn tip, slightly less blue colour and slightly less dense structure.[1ES24480]

3cy+ March, showing a uniform set of post-breeding TT. [1ES24475]

Cyanistes caeruleus - spring