Brief synthesisThe tiny archipelago of St Kilda, lying off the west coast of mainland Scotland, is breathtaking. The islands’ isolation has led to two outstanding examples of remote island ecological colonisation and subsequent genetic divergence in the two endemic sub-species, the St Kilda Wren and St Kilda Fieldmouse. They provide a living testament to the longevity of human occupation of St Kilda and, in addition, are a potentially significant genetic resource. Criterion (iii): St Kilda bears exceptional testimony to over two millennia of human occupation in extreme conditions. Criterion (x): St Kilda is one of the major sites in the North Atlantic and Europe for seabirds with over 1,000,000 birds using the island.