An "exceptional number" of North American birds have been seen in Cornwall after being blown off course by a hurricane, an organisation said.
This autumn, 18 species native to the Americas were seen compared to 10 in 2010 and seven in 2009, the Cornwall Birding Association said.
Hurricane Katia, which affected the East Coast of the US in early autumn, was behind the "influx", it added.
The RSPB said some good species had arrived this autumn in the south west.
The association's Paul Freestone said: "We have certainly had an excellent autumn with an exceptional number of American vagrants.
"The hurricane created ideal conditions for pushing migrating American landbirds across the Atlantic to our shores."
'Many will die'
Species reported in Cornwall from the Americas between August and November included wading birds such as the lesser yellowlegs and spotted sandpiper and small birds like the scarlet tanager and red-eyed vireo.
Tony Whitehead, from the RSPB, said the combination of birds migrating across the Americas and the weather system had caused them to arrive in the UK.
"The birds will arrive exhausted, with some surviving for a while and living amongst similar UK species, but many will die shortly after they arrive," he added.
Mr Freestone said the number of each species that reached Cornwall this year had increased compared to autumns of 2009 and 2010, with most species arriving around or shortly after the hurricane hit the East Coast of the US.
During the autumn, there were about 20 separate reports of a wading bird that migrates from North to South America, called a buff breasted sandpiper.
The species was seen at various locations in Cornwall, including at Marazion, Wadebridge and the Lizard, he said.
This was compared to three in 2010 and two in 2009.
The rarities were reported and counted by birdwatchers throughout the season and collated by the association.
Two species seen this autumn, a wading bird called a greater yellowlegs and a songbird called the scarlet tanager, have both only ever been recorded in Cornwall on one other occasion, Mr Freestone said.
Hurricane Katia caused large waves and strong winds off the East Coast of the US.
The remnants of the hurricane caused storm-force winds and heavy rain to affect areas of the UK in September.