Birders and snappers have flocked to a Sussex park to see a rare bird normally resident in Asia.
But experts believe the bird, a red breasted goose spotted in Tilgate Park and near Ifield Millpond in Crawley over the weekend, is escaped from captivity.
The goose, considered vulnerable by the International Union for Conservation of Nature, breed in Arctic Siberia but migrates in winter along northwestern shores of the Black Sea in Bulgaria, Romania and Ukraine.
It has been captured on camera by members of the Argus Camera Club.
But Dr Viola Ross-Smith, science communications manager for the British trust for Ornithology, said: "Given the time of year and location, and the fact that we can just about make out a yellow ring on this bird's leg, it seems highly likely that it has escaped from an aviary collection somewhere.
"We do get wild red-breasted geese coming to Britain, but typically later in the year - November is the peak time for these birds.
"These are birds breeding in Siberia and instead of migrating to their normal wintering grounds in South East Europe, they come here and hang out in flocks with other migratory geese species, like Brent Geese and Barnacle Geese. They are normally found nearer to the coast."
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Dr Ross-Smith believes this is the most likely explanation for the goose's recent appearances in Crawley.
Sussex is a good county for birdwatching, though, and wild rare birds have been spotted this year.
Most notably a citrine wagtail, a scarce visitor to the UK which is normally resident in north Asia, Russia and small parts of western Europe, was spotted at Widewater Lagoon in Lancing this spring.
The RSPB confirmed the identification of the bird as a citrine wagtail.
A spokeswoman for the charity said: "Citrine wagtails are a rare sighting here but are becoming an increasing vagrant (a species that is currently outside their wintering and breeding area) to western Europe and are now breeding in Poland.
"Most sightings are recorded during autumn with some spring records occurring. We are not aware of any other sightings in the UK at the moment."
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