Europe's biggest snake 'thriving' in UK and living in people's attics, study finds
10 February 2025, 19:08
Europe’s biggest snakes are “thriving” in the UK and are taking refuge inside people’s homes to cope with the cold weather, a new study has found.
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The Aesculapian snake, which can grow up to two metres in length, has established a healthy population in parts of North Wales and London after escaping a zoo in the 1970s.
The study observed that the snakes, which are native to Southern Europe, were “fond of human homes” as they looked for warmth in “attics and wall cavities”.
However, despite the species being non-venomous, the Government will soon consider adding it to the list of alien species of special concern, which would be grounds for their eradication.
Professor Wolfgang Wüster, a snake scientist from Bangor University and co-author of the study, has said he would either like to see the snakes given the same protections as native species or simply be left alone.
He said: “It would be both a tragedy and a travesty if we eradicated a harmless species that is now thriving in only a couple of places in the UK when the same species is threatened and declining just a few hundred miles away in continental Europe.”
The Aesculapian snakes mainly feed on small rodents like rats and mice and don't pose any threat to humans or pets.
Even within its native range, Professor Wüster points out that there has never been a report of an Aesculapian snake harming a pet.
“Aesculapian snakes are of course perfectly harmless and can just be picked up – even if they bite, the worst consequence would be some very minor scratches,” he said.
The snakes were also found to coexist well with the normal suburban wildlife and there was no indication that native species were suffering due to their presence.
Their normal range extends over southern Europe from Spain to the Caucasus, but scientists say their “climate envelope” is now shifting further north.
Currently, Britain's Aesculapian snakes can only be found along the Regent's Canal, London, and around Colwyn Bay, Wales.
The snakes were introduced to Wales in the 1970s when an “unknown number of individuals” escaped from the Welsh Mountain Zoo after their enclosure collapsed.
Since then, these escapees have established a stable breeding population in the area surrounding the zoo.
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In the study, published in PLOS One, Dr Tom Major and his co-authors caught 21 Aesculapian snakes and fitted them with radio trackers before putting them back where they found them.
By following their movements over two summers, they found that the snakes were surviving by warming up inside human residences.
The researchers write: “We observed Aesculapian snakes actively seeking and returning to use inhabited buildings, and climbing large structures to access the attics and wall cavities of houses.”
Male snakes were particularly fond of human homes, while females generally preferred to live in wooded areas.
The researchers point out that this behaviour is very unusual compared to other UK snake species like adders and smooth snakes which typically avoid built-up areas.
Writing in The Conversation, Dr Major said “They were frequently entering buildings – relatively warm refuges – while they were digesting food or preparing to shed their skin.
“They also used garden compost bins for shelter and to incubate their eggs.”
If you do find a snake in your home Professor Wüster says the best thing to do is call the RSPCA rather than risk trying to remove it yourself.
