Lemurs are usually found on the tropical island of Madagascar so vets were stunned when one of the animals was admitted to hospital, suffering from hypothermia, after being discovered in sub-zero conditions on a common in the UK.
The severely ill ring-tailed primate, who has been named King Julien after the character in the animated film Madagascar, was found on Tooting Common in south-west London on Tuesday night.
He had collapsed in the sub-zero temperatures and was diagnosed with hypothermia, severe dehydration and shock by staff at the Blue Cross animal hospital in Victoria, London.
He was put on a drip and taken to the hospital's isolation unit for close monitoring.
Mark Bossley, Blue Cross chief vet at Victoria animal hospital, said: "We were very concerned about King Julien's health as he was very cold, scared and didn't want to eat.
"But our nurses managed to coax him into taking some drops of honey from a syringe, then he gradually started eating bits of banana and grapes."
The animal charity said there was no way of knowing where the lemur had come from. The creatures originate from the island of Madagascar in Africa and require a special licence to own.
Mr Bossley added: "We mainly treat cats and dogs at the Blue Cross but we do get the odd snake or tortoise, and we have been known to treat chickens, goats and even possums.
"But this has got to be the most unusual animal we've ever taken in. How a ring-tailed lemur turned up in Tooting Common, I'll never know."
The lemur is now on the road to recovery and strong enough to leave the hospital. He will now be transferred to the Specialist Wildlife Services who will try to rehome him.