AGE – BEST CRITERIA:
In 1cy, all SS are uniformly juvenile, and show juvenile type barring. Older age classes show (most or all) SS with adult type barring, and in c. 35% of the birds at Ottenby, two different generations of SS are present. Two to four age categories are discernable, depending on the extent of the post-breeding moult of the individual.
1cy October (male). Uniformly juvenile SS, lacking moult contrasts. The SS shows five bars (and a sixth bar is barely visible behind the GC tips). The bars are medium brownish and rather narrow, and the ground colour of the SS is rather warm yellowish brown. 
2cy+ November (male). SS are uniformly post-breeding, showing no moult contrast (if a moult contrast is present, the age may be able to specify to 2cy or 3cy+). The SS show four adult type bars (a fifth bar is just visible behind the tips of the GC), rather broad and dark blackish-brown. The ground colour of the SS is rather cold greyish-brown. 
2cy October. Birds with less extensive moult of remiges show moult contrasts in the arm. The unmoulted SS3-4 and SS7-9 are of typical juvenile type, showing five or six narrow bars, in contrast to the surrounding SS showing adult pattern with four broad bars. 
3cy+ October (male). Birds showing moult contrast in SS, and where the old (worn) generation shows adult type pattern (similar barring as the adjecent fresh feathers) are possible to specify as 3cy+. Note that wear have made the unmoulted SS paler yellowish-brown. 
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