Plectrophenax nivalis - Autumn

Plectrophenax nivalis - autumn

Snow Bunting

AGE – BEST CRITERIA:

1cy show moult contrast in the wing, often (c. 35% of the birds) between post-juvenile MC and juvenile GC, but many birds (c. 56%) included 1-2 innermost GC. Very rarely, TT may also be included. Adults show a uniform and fresh wing. Shape and pattern of RR are useful as well as pattern and shape of PC.

A general difference in coloration and pattern of feathers is evident between 1cy and adult birds with 1cy birds most often having more extensive black areas on PC, RR, PP and SS. However, to determine the age based solely upon the amount of black in the feathers is not recommended since the variation is pronounced.

1cy:

Always show a moult contrast in the wing, often situated between MC and GC or with a few (1-4) inner GC being moulted. Rarely, one or more TT may have been included in the moult. The centra of post-juvenile coverts are, in the cases of inner GC, MC and LC in males and all coverts in females, black to dark ashy grey compared to the more faded grey or greyish-brown of the juvenile coverts (middle and outer GC in males are hard to asses since they often are dominantly white). Post-juvenile GC show deeper rusty brown tips than unmoulted juvenile, with the tips being less abraded, at least until late autumn-early winter.
Juvenile RR generally show abraded and more pointed tips, and the blackish centra of R1 is more pointed than in adults. The margin between blackish centra and lighter edges of R1 is thinner and diffuse. R4 most often show extensive black markings.
Juvenile PC show more extensive black areas as well as being (on average) slightly more pointed and abraded than in adult birds (however, there is a clear variation between individuals and between sexes).

2cy+:

Uniform plumage lacking any moult contrast (though rare occasions of retained/forgotten feathers are known to occur).
Whole wing and tail in better condition with broader and denser feathers, and (esp. in males) blackish and black parts being more intensely jet black and with better gloss. Wear might become harder to asses in late winter.
Tips of RR generally blunter and broader with sharper contrast between black centra and broader light edges of R1. R4 in males show limited and well-defined black markings.
Generally show less extensive black tips of PC and SS and sharper contrast between dark and light parts of the feathers, although variation (esp. in females) can be great.

1cy (male) November, showing retained juvenile GC, TT and AL contrasting with post-juvenile MC and LC. Unmoulted GC show abraded tips and blackish grey centra. [3218283]

1cy (male) November. Retained juvenile GC1-8 contrast to post-juvenile GC9-10. Juvenile GC are centered dark brownish-grey in contrast to the black centra of the post-juvenilr feathers as well as having paler buffish, rather than rusty-brown tips. [3218278]

1cy (female) November. Retained juvenile GC, TT and AL in contrast to the more dark-centered, post-juvenile LC and MC. [3218281]

1cy (female) November with retained juvenile GC1-8 in contrast to post-juvenile GC9-10, MC and LC. Juvenile GC tend to be dark brownish-grey in contrast to the blackish-grey in the moulted feathers as well as having paler buffish, rather than rusty-brown tips and fringes. [3218289]

2cy+ (male) November. Uniform, fresh wing with jet black feather centra to inner GC and pure white LC, MC and outer GC. Note that some white is showing at the tips of inner GC. [3218310]

2cy+ (female) November showing uniform, fresh wing without any contrasts between the wing-c. GC are broad with neat fringes and blackish-grey centra. [3218275]

1cy (male) November with rather narrow juvenile PC and AL. The PC are slightly abraded and show buffish fringes and indistinct border between light and dark parts of the feathers. Note that the blackish parts are rather extensive. [3218283]

1cy (male) November showing variation in the distribution of dark tips in PC. Indistinct border between blackish tips and white in PC. The juvenile AL shows a brownish-black colour. [3218278]

1cy (female) November showing narrow, pointed, rather loose structure and brownish-black colour to the juvenile PC and AL. [3218281]

1cy (female) November showing more difficult (rather adult-like) juvenile PC with broader, rounder tips. [3218272]

2cy+ (male) November with broad, fresh adult-type PC and AL. Jet-black AL, tips of PC and bases to PP. Sharp border between black and white in PC. [3218310]

2cy+ (female) November with broad, fresh adult-type PC and AL. Fringes are whitish and broader than in most 1cy birds. [3218275]

1cy (male) November with narrow, juvenile TT. Note post-juvenile GC9-10. Juvenile TT often appear rather dark-centered with vivid, rusty-brown tips, not as pale as retained juvenile GC. [3218278]

1cy (female) November with narrow, juvenile TT. Note post-juvenile GC9-10. [3218289]

2cy+ (male) November with broad, fresh, adult-type TT, GC and SS showing no contrast between generations and with black, glossy centra. [3218310]

2cy+ (female) November with broad, fresh, adult-type TT, GC and SS showing no contrast between generations. [3218275]

1cy (male) November showing typical juvenile tail-feathers. Pointed and narrow with the blackish centra of R1 extending with thin buffish edges all the way to the tip. Note extensive black tip on R4. [3218266]

1cy (male) November. A rather pale individual showing variation in R4 coloration. Faded dark markings on R4. [3218278]

1cy (female) November showing typical juvenile tail-feathers. Pointed and narrow with the blackish centra of R1 extending with thin buffish edges all the way to the tip. [3218289]

1cy (female) November showing variation with broader but still rather pointed RR. [3218281]

2cy+ (male) November. Broad, rounded and glossy adult-type RR. Black centra of R1 bordered by a broad whitish tip. R4 with limited, well-defined black markings. [3218310]

2cy+ (female) November. Fresh, broad, rounded adult-type RR. Wide brown tips of R1. [3218275]

More Plectrophenax nivalis:
Sexing autumn
Moult

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