A wild boar which has been on the loose in Alderney for more than a month is thought to have swum there from the nearby French coast.
The boar found its way into a pig farm on Friday but, when approached, escaped by jumping over a 1m (3ft) stock fence.
Farm owner Tess Woodnutt said she would not have believed the animal could jump so high from a standing start, if she had not seen it with her own eyes.
Islanders have dubbed the boar "ghost pig", as it has only been seen at dusk.
Mrs Woodnutt said she first became aware of the boar on 27 September, when she was on holiday and received a call from a fellow islander saying one of their 40 pigs had escaped.
Her son Jake immediately went to the farm and soon established no pigs were missing.
Steve Shaw, who was Alderney harbour master for 25 years, said he did not believe it would be possible for a wild boar to get to the island by boat without the crew noticing, and he had never heard of a wild boar being found on any vessel.
Some islanders have speculated the animal could be an "iron age pig", which have been farmed on the island.
However, Alan Woodnutt, Tess's husband, said he was certain it was not.
"Iron age pigs are a cross between a wild boar and a Tamworth," he said.
"They look a bit like a wild boar but this animal was not the progeny of an iron age pig."
Mrs Woodnutt said the boar's arrival on the island was a mystery but she had had it confirmed to her by an expert in the UK that a wild boar could swim long distances in open water.
Wild boar are commonly found in Normandy, the coast of which lies seven miles (11km) to the east of Alderney.
Duty Insp Kieran McGrath from Guernsey Police said islanders should contact them if they spotted the animal and should not approach it themselves, as any wild boar could be dangerous when cornered.