Individual white barnacle geese have been occasionally visiting northern of Norway with the flocks for years now. They are characterised by pale feathers, but are not true albinos, as they have black eyes, beaks and legs.

These peculiar birds are the result of a genetic hiccup, called leucism. The standard black, grey and white gene is dominant in barnacle geese. An abnormality results in the white (or leucistic) gene which is double recessive. Of the three distinct breeding populations, we think that it’s only the Svalbard population that has ever thrown up this morph.

The barnacle goose is a medium-sized goose, 55–70 cm (22–28 in) long, with a wingspan of 130–145 cm (51–57 in) and a body mass of 1.21–2.23 kg (2.7–4.9 lb). It has a white face and black head, neck, and upper breast. Its belly is white. The wings and its back are silver-gray with black-and-white bars that look like they are shining when the light reflects on it. During flight, a V-shaped white rump patch and the silver-gray underwing linings are visible.

Barnacle geese breed mainly on the Arctic islands of the North Atlantic. There are three main populations, with separate breeding and wintering ranges - from west to east:

Breeding in eastern Greenland, wintering on the Hebrides of western Scotland and in western Ireland, population about 40,000
Breeding in southeast and northwest Iceland, population about 1000
Breeding on Svalbard, Norway, wintering on the Solway Firth on the England/Scotland border, population about 24,000
Breeding on Novaya Zemlya, Russia, wintering in the Netherlands, population about 130,000
A recent population, derived from the Novaya Zemlya population, has become established since 1975 breeding on the islands and coasts of the Baltic Sea (Estonia, Finland, Denmark, and Sweden), and wintering in the Netherlands and Germany. Its population numbers about 8,000.

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Previous post : May 15th, 2022

What Is Leucism?

Leucism is a term used to describe a wide variety of conditions which result in the partial loss of pigmentation in an animal—which causes white, pale, or patchy coloration of the skin, hair, feathers, scales or cuticles, but not the eyes.

Leucism, or leukism, is an abnormal plumage condition caused by a genetic mutation that prevents pigment, particularly melanin, from being properly deposited on a bird’s feathers. As a result, the birds do not have the normal, classic plumage colors listed in field guides or seen in most photos. Instead, the plumage may have several color changes, including:

Bold white patches where the bird should not have any
Paler overall plumage that looks faint, diluted, or bleached
Overall white plumage with little or no color visible

The degree of leucism, including the brightness of the white and the extent of pigment loss, will vary depending on the bird’s genetic makeup. Birds that show only white patches or sections of leucistic feathers, often in symmetrical patterns, are often called pied or piebald birds, while birds with fully white plumage are referred to as leucistic birds.

Here are some pictures of a leucistic common gull in north of Norway: