At dawn yesterday, an enthusiast from Penzance, who had travelled through the night, was among the 300 birdwatchers observing the short-billed dowitcher pulling worms from the seaweed covered mud at Rosehearty, near Fraserburgh.
The identity of the dowitcher (limnodromus griseus) had been confirmed by its distinctive call less than 24 hours before. Details were transmitted around Britain by Birdnet, an agency which pages birdwatchers with news of interesting sightings.
"The phones were going berserk yesterday once people realised what was happening," said Andrew Webb, the official bird recorder in north-east Scotland. He said some people watched from dawn until dusk.
"This is the most exciting event of the birdwatching year," said Robert Coleman of the Royal Society for the Protection of Birds. "Word gets around very quickly on the grapevine. When a rare bird like this turns up, we all rally together to make sure that everyone gets a chance to see it.
"There have only ever been two sightings of this bird in Europe - one in Ireland, the other in Germany. It is an American wading bird that has probably been picked up by one of the hurricanes and blown thousands of miles off course. If it stays until the weekend I would expect over 1,000 people to turn up."
A number of other, more common, American waders, notably pectoral, white- rumped and semi-palmated sandpipers, have been blown on to the Western Isles over the past week.
The short-billed dowitcher is about the size of a pigeon, has long legs and is grey with a long probing beak. The one found in Aberdeenshire has some wing feathers missing, which may reflect a traumatic journey, but, according to experts, it does not seem too exhausted. In order not to disturb the dowitcher further, the birdwatchers are not venturing closer than 25 metres.
Mr Webb said the bird's sex was uncertain. It was feeding well, but he did not expect it to remain in Aberdeenshire for more than a few days. "It will probably move south as winter comes," he said.