The aerial census was carried out last year by Profs Mike Harris and Sarah Wanless from the Centre for Ecology and Hydrology, and Stuart Murray, on behalf of Scottish Natural Heritage (SNH). The results, published in the June edition of the ornithological journal 'British Birds', showed around 60,000 apparently occupied nests in St Kilda, a similar number to the previous survey of ten years ago.

On the Bass Rock however the picture is very different, with nests there having more than doubled in number from 21,559 to 48,065 over a 19 year period. 

Scotland is home to 70% of British and Irish gannets, and 44% of the world population. Together St Kilda and the Bass hold a quarter of the world gannets. But where there has been little spread in the St Kilda colony, virtually the whole summit of the Bass is now occupied by nesting gannets. Whether this means it will eventually match or surpass St. Kilda depends on how many new pairs the Bass can physically accommodate. Stuart Murray said: "There may not be much more room on the Bass. Nearly all the suitable ground is now utilised with only the lighthouse walled garden on the summit still being unoccupied."

The species also nests on the other side of the Atlantic, around the Gulf of St Lawrence, where Canadian scientists have detected a significant increase on Bonaventure Island, off the coast of Quebec. There does seem to be room, sometime in the future, for this colony to overtake St Kilda as the world's biggest, but that will depend upon the species continuing to thrive.

There is other evidence that the increase in gannet numbers is beginning to slow. Some colonies, like St Kilda, have remained stable in the last decade and a few others have even decreased slightly. In the meantime the St Kilda National Nature Reserve and World Heritage Site still retains its status as the world's largest North Atlantic gannet colony.