Barnacle Geese: The curious tale of the bird which people believed grew on trees

A curious set of coincidences surrounding barnacle geese prompted our forebears to draw some strange conclusions about where Branta leucopsis came from — generating myths that lasted centuries, as Ian Morton discovers.

Wetland and waterside folk knew about ducks, geese and swans — how they paired, nested and produced eggs and fledglings.

There was, however, one notable exception: a medium-sized adult goose with a white face and a black neck, which appeared annually without the usual evidence of propagation. Imaginative ancestors made a logical assumption when they came across timbers floating in from the sea, with small creatures each attached by means of a grey-black foot. This they likened to the neck of that black-and-white goose and reasoned that this barnacle must be the earliest stage of its development.

The theory entered literature. The 11th-century Exeter Books of Riddles, an Anglo-Saxon poetic relic, posed this conundrum: ‘My beak was close fettered, the currents of ocean running cold beneath me. There I grew in the sea, my body close to the moving wood. I was alive when I came from the water clad all in black, but part of me white. When the living air lifted me up, the wind from the wave bore me afar.’

Royal clerk Giraldus Cambrensis wrote, in his Topographia Hibernica of 1187, that the barnacles were ‘embryos of birds of this species on the seashore… they hang down by their beaks from a piece of fir timber tossed along in the sea as if they were seaweed, covered with shells and already formed… they derive their food from the sap of the wood or from the sea by a secret and most wonderful process of alimentation’. The compendium of 13th-century knowledge Speculum Maius, by Vincent of Beauvais, confirmed the theory. The barnacle goose was thus established in the natural narrative.

Barnacle Goose (Branta leucopsis) gosling stretching. ©Peter Hering / Minden / naturepl

Folklore offered an alternative: the goose was the fruit of waterside trees, hanging from the branches by its beak as it ripened. Irish clergy happily ate it during Lent and on Fridays, on the grounds that it was fruit, not flesh. The belief became sufficiently widespread for Pope Innocent III to issue a 1215 edict that ordered the goose off the refectory menu. He did not dispute its ‘unusual reproduction’, but ruled that, as these geese lived and fed like ducks, they were, therefore, birds.

Still the myth lived on. The Travels of Sir John Mandeville of 1356 recorded that ‘in our country there were trees that bear a fruit that become birds flying, and those that fell in the water live, and they that fall on the earth die’. After visiting Scotland in 1435, Aeneas Silvius Bartolomeus, later Pope Pius II, wrote: ‘I heard that in Scotland there was once a tree growing on the bank of a river which produced fruits shaped like ducks.

When these were nearly ripe they dropped down of their own accord, some on to the earth and some into the water. Those that landed on the earth rotted away, but those that sank into the water instantly came to life, swam out from below the water and immediately flew into the air equipped with feathers and wings. When I eagerly investigated this matter… the famous tree was to be found not in Scotland but in the Orkney Islands.’

Barnacle geese: What you need to know

  • The barnacle goose is protected, with a UK wintering population of some 90,000 individuals
  • Barnacle goslings have a tough start in life. The adults nest on North Atlantic island cliffs to avoid foxes and the young must launch to ground level to reach feeding areas. The plunge — and patient foxes — account for 50%
  • The sessile or acorn barnacle clustered on shoreline rocks was never involved in the goose saga, but offers a medical breakthrough. It cleans its rock and adheres by means of a powerful glycoprotein, a process that scientists at the Mayo Clinic and the Massachusetts Institute of Technology have replicated as a paste. It is a promising means of instantly cleaning a wound and stemming excessive blood loss, potentially lifesaving in civilian and battlefield emergencies
  • In the absence of migratory knowledge, the winter disappearance of certain species gave rise to other wondrous theories. Mediterranean white cranes flew to Africa to do battle with pygmy folk, redstarts turned into robins, garden warblers became blackcaps and swallows took refuge in mud or overwintered on the moon, together with storks and turtledoves. The 17th-century Cornish clergyman Charles Morton, who became vice-president of Harvard, worked out that the moon was 179,712 miles away and that the avian travellers survived on stored fat and slept through each return journey, which took 60 days at 125mph

Both stories had been denounced at the highest secular level. The 13th-century Holy Roman Emperor Frederick II noted ‘a curious popular tradition that they spring from dead trees, that this goose hangs from the dead wood by its beak until it is old and strong enough to fly’ and sent envoys north to bring him examples of the barnacles.

He found ‘no resemblance to any avian body. We therefore doubt the truth of this legend. In our opinion this superstition arose from the fact that barnacle geese breed in such remote latitudes that men, in ignorance of their real nesting place, invented this explanation’. His insightful judgement was supported by a contemporary, saintly philosopher Albertus Magnus, who mated a barnacle goose with a domestic goose and witnessed the eggs and chicks that resulted. The legend, he declared, was ‘altogether absurd’.

Flock of Barnacle Geese (Branta leucopsis) foraging on grassland of farm. Photo by: Arterra/Universal Images Group via Getty Images

Yet the story was simply too good to lose. Early-16th-century historian Hector Boece, principal of King’s College Aberdeen, admitted that ‘geese commonly called clacks… are wrongly imagined to be born on trees’, but went on to retell the alternative tale, reporting that Alex Galloway, parson of Kinkell, picked up some driftwood ‘and saw that seashells were clinging to it… opened them up, whereupon he was more amazed than ever for within them he discovered not sea creatures but rather birds of a proportionally small size’.

The tree connection also persisted. Geese as hanging fruit were illustrated in the 1552 Cosmographia by Sebastian Muenster and, in his General Historie of Plantes, published in 1597, herbalist and gardener John Gerard wrote — complete with an illustration — that ‘there are found in the north parts of Scotland and the islands adjacent, called Orchades, certain trees of white colour tending to russet wherein are contained little living creatures which of shells in time do open and out of them grow those living things which falling into the water do become foules whom we call Barnakles, in the north of England brant geese, and in Lancashire tree geese… this much by the writing of others and also from the mouths of people of those parts which may very well accord with truth’.

Two Barnacle Geese (Branta leucopsis) in flight. (Photo by: Arterra/Universal Images Group via Getty Images)

In 1751, English naturalist John Hill recorded reports of Dutch sailors returning from Greenland ‘who have found immense numbers of their nests with the females sitting on the eggs’. He attributed the old legend to ‘ignorant fishermen’ who mistook the barnacles’ feeding filaments for developing feathers.

The truth was emerging, but, in 1767, the father of modern scientific order Carl Linnaeus classified the pedunculate barnacle as Lepas anserifera, meaning goose-forming, and this remains its scientific identity.

Although the bird was classified by Johann Bechstein, in 1803, as Branta leucopsis, a combination of the Old Norse for burnt and the Greek words for white and face, it is forever our barnacle goose.