Range of the barnacle goose (note: also breeds in Iceland; grey is indicated as feral, but these populations were established by both wild birds and escaped captives, seetext)
Thebarnacle goose (Branta leucopsis) is aspecies ofgoose that belongs to the genusBranta of black geese, which contains species with extensive black in theplumage, distinguishing them from the greyAnser species. Despite its superficial similarity to thebrant goose, genetic analysis has shown its closest relative is thecackling goose.[2]
The barnacle goose was firstclassified taxonomically by Johann Matthäus Bechstein in 1803.Branta is a Latinised form ofOld NorseBrandgás, "burnt [black] goose" and the specific epithet is from theAncient Greekleukos "white", andopsis "faced".[3]
In the medieval period, the barnacle goose and the similarbrant goose were not distinguished, andwere formerly believed to spawn from thegoose barnacle.[4] This gave rise to the English name of the barnacle goose and the scientific name of the brant goose.[3] The barnacle myth can be dated back to at least the 12th century.Gerald of Wales claimed to have seen these birds hanging down from pieces of timber,William Turner accepted the theory, andJohn Gerard claimed to have seen the birds emerging from their shells. The legend persisted until the end of the 18th century. InCounty Kerry, until relatively recently, Catholics abstaining from meat duringLent could still eat this bird because it was considered as fish.[5] It is sometimes claimed that the word comes from aCeltic word for "limpet", but the sense-history seems to go in the opposite direction.[6]
The barnacle goose is a medium-sized goose, 55–70 cm (22–28 in) long, with a wingspan of 120–145 cm (47–57 in) and a weight of 1.21–2.23 kg (2.7–4.9 lb).[7][8][9][10] It has a white face and black head, neck, and upper breast. Its belly is white. The wings and its back are silver-grey 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-grey underwing linings are visible. They look similar tocackling geese but have grey and white instead of brown bodies, and more extensive white on the head; fromCanada geese they are additionally distinguished by being smaller, and having smaller beaks. The juveniles are similar to the adults, but like with all geese, can be distinguished by the rounded rather than square-ended mantle and flank feathers.[7]
There are three original populations of barnacle geese, with separate breeding and wintering ranges. Since the 1960s, two new breeding populations have established themselves, both located alongmigration routes of two of the original populations. The five populations are:
Breeding in easternGreenland, wintering on theHebrides of westernScotland and in westernIreland. Population increased from about 7,000 individuals in the 1960s to 44,000 in 2011.[11]
A recently established population, derived from the Greenland population, has bred more-or-less regularly inIceland since 1964. The population has rapidly increased in the last few decades, with more than 4000 breeding pairs in 2024.[12] They winter in the same area as Greenland population.[13]
Breeding onSvalbard,Norway, and wintering almost entirely inSolway Firth on the England/Scotland border, with small numbers elsewhere in the region, particularly aroundBudle Bay in Northumberland. This population increased from a few hundred individuals in the 1940s to about 34,000 in 2004,[14][15] and 40,000 by the start of the 2020s.[16]
A recent population, derived from the Russian population along with escaped captive birds, has become established since 1971; breeding on islands in theBaltic Sea, and on islands and coasts of the southernNorth Sea (Estonia,Finland,Sweden, Denmark, the Netherlands, Germany andBelgium). Winters in or near breeding range or moves to the Wadden Sea. Some exchange with Russian population continues. Rapidly increasing; the Danish, Dutch and Swedish populations each contain several thousand breeding pairs, and the Belgian, Estonian, Finnish and German populations each contain several hundred breeding pairs.[18][19][20][21]
The species has been recorded as avagrant in easternCanada, the NortheasternUnited States andIndia; care must be taken to distinguish these wild birds from escaped individuals, as barnacle geese are popular waterfowl with collectors.[22][23]
Barnacle geese frequently build their nests high on mountaincliffs, away from predators, primarilyArctic foxes andpolar bears, but also away from their feeding grounds such as lakes, rivers. Like all geese, thegoslings are not fed by the adults. Instead of bringing food to the newly hatched goslings, the goslings learn to jump down the cliff, possibly from heights of hundreds of feet.[24]
Unable to fly, the goslings, in their first days of life, jump off the cliff and fall; their small size, feathery down, and very light weight helps to protect some of them from serious injury when they hit the rocks below, but many die from the impact. Arctic foxes are attracted by the noise made by the parent geese during this time, and capture many dead or injured goslings. The foxes also stalk the young as they are led by the parents to wetland feeding areas.[25] Due to these hardships only 50% of the chicks survive the first month.[26]
The Svalbard population was heavily reduced by the early 2020shighly pathogenic avian influenza (HPAI) outbreak, with mass mortality involving 11,400 killed in the 2021/22 winter, or about 31% of the population.[16] The two subsequent breeding seasons were however highly productive, allowing the population to recover to close to its former levels by the 2023/24 winter.[16]
The natural history of the barnacle goose was long surrounded with a legend claiming that they wereborn of driftwood:
Nature produces [Bernacae] against Nature in the most extraordinary way. They are like marsh geese but somewhat smaller. They are produced from fir timber tossed along the sea, and are at first like gum. Afterwards they hang down by their beaks as if they were a seaweed attached to the timber, and are surrounded by shells in order to grow more freely. Having thus in process of time been clothed with a strong coat of feathers, they either fall into the water or fly freely away into the air. They derived their food and growth from the sap of the wood or from the sea, by a secret and most wonderful process of alimentation. I have frequently seen, with my own eyes, more than a thousand of these small bodies of birds, hanging down on the sea-shore from one piece of timber, enclosed in their shells, and already formed. They do not breed and lay eggs like other birds, nor do they ever hatch any eggs, nor do they seem to build nests in any corner of the earth.[28]
The legend was widely repeated in, for example,Vincent of Beauvais's great encyclopedia. However, it was also criticized by other medieval authors, includingAlbertus Magnus.[28]
This belief may be related to the fact that these geese were never seen in summer, when they were supposedly developing underwater (they were actually breeding in remote Arctic regions) in the form ofbarnacles—which came to have the name "barnacle" because of this legend.[29]
Based on these legends—indeed, the legends may have been invented for this purpose[30]—some Irish clerics considered barnacle goose flesh to be acceptablefast day food, a practice that was criticized byGiraldus Cambrensis, a Welsh author:
...Bishops and religious men (viri religiosi) in some parts of Ireland do not scruple to dine off these birds at the time of fasting, because they are not flesh nor born of flesh... But in so doing they are led into sin. For if anyone were to eat of the leg of our first parent (Adam) although he was not born of flesh, that person could not be adjudged innocent of eating meat.[28]
At theFourth Council of the Lateran (1215),Pope Innocent III explicitly prohibited the eating of these geese during Lent, arguing that despite their unusual reproduction, they lived and fed like ducks and so were of the same nature as other birds.[31]
The question of the nature of barnacle geese also came up as a matter of Jewish dietary law in theHalakha, andRabbeinu Tam (1100–71) determined that they werekosher (even if born of trees) and should be slaughtered followingthe normal prescriptions for birds.[28]
In one Jewish legend, the barnacle goose is purported to have its beak forever attached to the tree from which it grew just as theAdne Sadeh is fixed to the earth by its navel cord.[32] The mythical barnacle tree, believed in theMiddle Ages to have barnacles that opened to reveal geese, may have a similar origin to the other legends already mentioned.[33]
^"...all the evidence shows that the name was originally applied to thebird which had the marvellous origin, not to theshell..."Oxford English Dictionary, 2nd Edition, 1989
^Lankester, Edwin Ray (1970) [1915].Diversions of a Naturalist. Books for Libraries Press. p. 119.ISBN0-8369-1471-6.this identification was due to the exercise of a little authority on the part of the clergy in both France and Britain, who were thus enabled to claim the abundant "barnacle goose" as a fish in its nature and origin rather than a fowl, and so to use it as food on the fast-days of the Church
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