Sunday, 18 December 2011



Snow Buntings exhibit a great deal of variation in the characters used for sexing. Intermediates occur, making it necessary to take all characters into consideration. Males are generally whiter and blacker than females of corresponding age. A bird with ALL WHITE primary coverts is a MALE. The lesser coverts are uniformly white in males but in a few cases, there are some small scattered spots. The secondaries are mainly white in males, occasionally with small black marks near the tip of the outer web. The dark tip of the primaries on the underwing is blackish and sharly set off in males. The dark centres of the scapulars are jet black, and the tips rounded or bluntly pointed in males, best visible on the middle feathers. The dark centres to the upper tail coverts are similar in this respect. They tend to end bluntly in adult males, and come to a point in first-year males, but intermediates do occur. Males have less dark in the third outermost pair of tail feathers than females, very little in adults and usually restricted to the tip of the inner web in first-year males. Males are on average larger than females, and many can be sexed on measurements.

In females, the primary coverts are mainly BLACKISH, with WHITE ONLY ON THE EDGES. The lesser coverts are greyish-brown to blackish, with some off-white tips, never appearing as white as in males. The secondaries are white, with the dark pattern on the tips ranging from small dark subterminal markings on the outer web in adults to about distal half of feathers. The dark tip of the primaries on the underwing is diffusely demarcated and browner. The tip of the dark centres of the middle scapulars is sharply pointed in females, and the base colour is browner or greyer than in males. The dark centres of the uppertail-coverts come to a point in females, often more so than in first-year males, but many are intermediates and the character is most useful in adults. In females, the dark pattern of the third outermost pair of tail feathers usually covers the centre inner web, the dark pattern normally dominating over white areas. Individuals showing intermediate characters frequently occur. These are either first-winter males or adult females, so correct ageing should solve the most difficult caes.


Juvenile Snow Buntings have a partial moult about three weeks after fledging, late July or August to September, involving head, body, lesser and median coverts and sometimes inner greater coverts and tertials. Adults moult completely after breeding, between the first half of July and September, taking between 28 and 37 days.

Some Snow Bunting plumages are ambiguous, but most can be aged based on a combination of criteria. However, with progress of wear and bleaching, ageing becomes progressively more difficult. MostBritish birds involve the form insulae, averaging more extensive dark patterning than other forms. Particularly, first-year males may show characters fairly typical of females, such as all-dark primary coverts, dark bases to the greater coverts and dark tips to the outer secondaries. Adult males frequently show dark tips to the primary coverts.

Juvenile tail feathers, which are retained throughout the first year, are more tapered than those of adults of both sexes. The tip of the dark centre of the innermost pair of tail feathers is more pointed in first-year birds. Between males of different ages there is usually a marked difference in the amount of dark on the third outermost pair of tail feathers. In adults, the dark pattern is usually restricted to a relatively short dark patch along the shaft. There is often a limited amount of dark on the inner web, usually a narrow patch, isolated from the shaft patch. In first-year males, the pattern along the shaft is longer than in adults and the dark pattern on the inner web is more extensive and usually connected to the shaft streak. This difference is also useful in most females.


Adult males often have the longest primary covert ALL WHITE, sometimes with a small dark spot at the tip. Adult females often show a similar pattern, with a spot near the tip, but with a varying amount of dark on the outer web. Quite frequently, the primary coverts of adult females are all dark, except for white bases on the inner web. In first-year birds of both sexes, the outer web is often all dark


In males and adult females, there is no black on the inner webs of the secondaries, except for a small dark spot near the tip of the outer web in some females. First-year females usually show dark patches on the outer three ones.


In adult males, the alula is BLACK, whereas it is DARK GREY in first-year males.


The dark centres of the longest uppertail coverts tend to end more bluntly in adult males, and come to a point in first-year males. Intermediates occur.


In adult males, the dark parts of the primaries are almost glossy black with sharply defined white fringes. Immature males have dark grey primaries, and the white fringes are often less well defined.

Text adapted from Urban Olsson

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