It sounds like a dog and was once said to start life as a mollusc. But this kind of barnacle is most certainly a bird, and one that provides some brilliant viewing opportunities at its main Scottish havens on Islay and by the Solway Firth.
What to look for
The barnacle is a small, dapper goose. Its three-tone plumage has striking contrasts between its all-black neck, white face and grey wings. Aside from its size, one of the ways to home-in on a barnacle goose is to listen for its calls, which are fast and shrill and can sound remarkably like a yapping dog.
The barnacle goose gets its name from an old notion that it began life in a shell, growing on a seashore ‘barnacle tree.’ A benefit of this belief was that people could use it as an excuse to eat goose during Lent - a time when the Church frowned on consumption of meat - on the basis that they weren’t eating flesh, but shellfish.
When and where to see
There are scatterings of barnacle geese in autumn and winter between the south isles of Orkney, through the Hebrides, along parts of the west coast and in the inner Solway Firth. Look from September until mid-April.
Two places in Scotland stand out as possibly the best barnacle goose flock viewing places in the world. In the south, Caerlaverock and nearby parts of the Solway Firth host the entire barnacle goose population from Svalbard in the high arctic (sometimes more than 24,000 birds). On Islay, Loch Gruinart is the hub for watching birds from the Greenland population, more than half of which winter on the island. Numbers here can top 30,000 birds.
For more information see the RSPB's barnacle goose page.