Lying in the Atlantic Ocean, 40 miles or so north-west of the Outer Hebrides, St Kilda is home to about one million breeding seabirds, which come to the islands each spring to breed and raise their young.
But for hundreds, perhaps thousands, of years, the UK archipelago was also home to "the bird people".
This extraordinary group of men, women and children lived what amounted to a hunter-gatherer lifestyle, right into the early decades of the 20th Century.
Their feathers were used to stuff pillows and bedding, and the whole skins of gannets, our largest seabird, were used as shoes
Surprisingly, perhaps, the St Kildan people rarely ate fish - it was simply too dangerous for the islands' small population of menfolk to head out to sea in a rowing boat in search of unpredictable and possibly non-existent shoals.
They also found fish rather bland and insipid - at least compared to their own diet of choice, seabirds.
We set out to tell their extraordinary story, and marvel at their bizarre lifestyle, some eight decades after they finally left the islands.
Bird oil medicine
Rare and historic footage of the islanders, to be broadcast during the BBC programme Birds Britannia, helps reveal the intimate relationship between these "bird people" and their feathered prey.
During the spring and summer months, the men of the main island, Hirta, clambered barefoot down steep cliff faces on ropes, clinging on with their prehensile toes.
Here, they harvested young gannets (known as gugas), auks and fulmars; while the women took puffins from their burrows on the nearby island of Dun.
As well as being eaten in vast quantities, the birds would be put to almost every conceivable use.
Their feathers were used to stuff pillows and bedding; the oil in the stomachs of fulmars was used both as fuel and as a primitive form of medicine; and the whole skins of gannets, our largest seabird, were used as shoes.
But the islanders had a problem: this amazing abundance of seabirds was only available for half the year.
During autumn and winter all these birds headed out into the Atlantic Ocean, leaving the cliffs and burrows deserted until the following spring.
To prevent themselves starving, the islanders came up with an ingenious solution: they built stone cairns, known as cleits, where they stored the carcasses of the birds.
The theory was that the wind passing through the gaps between the stones would dry the birds; though as one observer pointed out, with the humid climate and high rainfall, the birds often ended up decayed rather than dried.
The bird people of St Kilda had little choice but to harvest seabirds in this way.
St Kilda is the most remote part of the United Kingdom.
When I visited St Kilda to film a programme with Bill Oddie, almost a decade ago, it took four days to get there - longer, incidentally, than I once took to get to Antarctica.
I had no idea what to expect.
Wildlife presenter Bill Oddie explains how the 'bird people of St Kilda' once lived
But it really was worth it; and not just because of the birds.
I recall coming up on the deck of our boat, as dawn broke.
As I looked up, the mist began to clear, revealing the massive stacks and cliffs of these incredible islands - what one of our Birds Britannia contributors, Donald Murray, described as being like the mythical sea-kingdom of Atlantis.
We spent just two days on St Kilda - two days that will always be in my memory.
It wasn't just the birds that stayed with me - amazing though they were - but the experience of walking down the village street, past the homes where these people lived right up to my own grandparents' day.
I felt as if I was walking back in time.
It is impossible for someone like me, brought up with every modern convenience, to imagine how the islanders lived their lives.
But just for a few brief moments I could sense the presence of the bird people of St Kilda around me.
Despite the rigours of their unique lifestyle, the bird people survived until the early 20th Century.
Then, following a gradual decline in the population, they made the difficult - and indeed irreversible - decision to leave their island home.
Eighty years ago, in August 1930, they set sail for a new life on the mainland, leaving behind an incredible place that remains home to millions of seabirds to this day.
The Seabirds episode of Birds Britannia will broadcast on BBC Four on Wednesday 17 November at 2100BST.
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