By James Clarke
BBC News, England
Bones may not be the only vulture flying free round England
Pumas, lynx and vultures may not be creatures people would expect to see in England.
But according to experts they could all be out there - some as escapees from zoos or wildlife parks and others as unexplained secretive residents of rural regions.
Reports of a tiger spotted in Yorkshire earlier this year remain unconfirmed, but other less-threatening but similarly-unlikely species are believed to be making England their home.
The changing climate could be a reason why breeds of owl and water fowl not normally found in the UK have been seen in this country, according to zoologist Jacqueline Pearson.
She is head of waterfowl at Blackbrook Zoological Park in Staffordshire, from where a vulture named Bones escaped in August.
Bones has not been re-captured and reported sightings of him have suggested he could be on a moor a few miles away.
People keen to help have reported seeing vultures further afield, but Ms Pearson and her fellow zoo keepers believe those vultures, spotted in locations including Cornwall, Norfolk and north Wales, could not be Bones.
"Knowing Bones, he hasn't got the instinct to go that far," she said.
"It would be different with some other birds but vultures are not hunters, they live off carrion [carcasses of already dead animals].
Police in Yorkshire received reports of a tiger on the loose this year
"Some birds of prey escape all the time, but when we began to realise there could be other vultures out there, we couldn't believe it."
Ms Pearson said any other vultures on the loose in Europe were likely to be escapees from zoos like Bones, but admitted they could be appearing for other reasons.
"Obviously with climate change there are things going on. There are griffin vultures in Spain and we're not that far from Spain.
"Owls seem to be on the move that we didn't know about, some European breeds are definitely moving into Britain."
In June North Yorkshire Police received several reports of a tiger on the loose in countryside near Tadcaster.
Lynx in freezer
A wildlife expert told officers the animal could have been a cub bought illegally and then released - and warned it could be very dangerous.
It was not confirmed that the animal people had spotted was a tiger, but whatever the cat was, it appears it is not alone.
Danny Bamping, of the British Big Cats Society (BBCS) said he receives about 200 reports a month of big cat sightings, with the number increasing over the past three to five years.
The BBCS was set up to scientifically identify, quantify, catalogue and protect the big cats roaming the British countryside, offering people the chance to report any big cats they have seen.
Mr Bamping said: "We're getting more reports than ever.
"The South West is still the area with most sightings but the area around the England-Wales border gets a lot too - they are rural areas, maybe that's why there are more there.
"They are mainly black cats, but others are brown, which I think are pumas, and there are also reports of big cats without tails, which would be lynx.
"About a third you can immediately disregard as hoaxes but that still leaves more than 60% which we take seriously."
Earlier this year it was confirmed Norfolk Police had found a dead lynx in a gamekeeper's freezer in the 1990s.
The cat was found in 1991 when officers searched the man's house after reports he had been killing birds of prey - but the identity of the animal was only made public this year after a request under the Freedom of Information Act.
Leopard in garden
It was confirmed the lynx had been shot while roaming near Great Witchingham - about 12 miles (19.3km) north west of Norwich.
Big cats sightings are not only the reserve of rural areas though - in 2005 the BBCS received a report from a man in south London that a "big black cat" had pounced on him at the bottom of his garden.
And it is not only wild big cats who may make their homes in the capital - in May magistrates gave conservationist Todd Dalton permission to keep a leopard in a cage in his garden in Peckham.
A resident of the South West?
Other animals which have unexpectedly found themselves in an unusual habitat have not fared so well.
SpongeBob, a squirrel monkey stolen from Chessington World of Adventures in Surrey in July, was bullied by other monkeys on his return and had to be moved to a new zoo in Battersea, south London.
And when Ralph, a 5ft tall South American rhea who escaped from his enclosure at a smallholding in Kent, was found four days later, his owner said he only had a 50-50 chance of survival because of the shock.
A Scottish-based group called the Wild Beasts Trust has received publicity for its aims of returning creatures such as wolves, bears, elk, boars, bison and walruses to the UK.
Members have told the BBC they are aiming to "bring back Britain's lost mammals", but the release of such animals would be illegal and the group's ambitions have been criticised as dangerous by politicians, farmers and the Countryside Alliance.
But if the group gets its way it could be that any "wild beasts" they do release find there are a number of others out there waiting for them already.