Researches have been tracking a species of snake that has not been seen in the UK for around 300,00 years.
There are only three types of snakes native to the UK - an adder, grass snake and a smooth snake.
However, there is a fourth species of "accidentally released snakes" that is quietly making itself at home in the UK.
The Aesculapian snake is native to central and southern Europe, but has now been accidentally re-introduced to the UK, according to BBC Countryfile.
It's estimated this particular snake species was last spotted in the UK around 300,000 years ago, the BBC wildlife experts added, disappearing during a previous ice age.
The Aesculapian snake, which can grow up to 2 metres in length, is non-venomous and mostly eats rodents such as rats.
They have long smooth-scaled bodies, round pupils and the adults are grey, olive or brownish in colour, according to Frog Life.
Juveniles have a well-defined dark stripe on the side of their heads as well as a dark mark (usually in the shape of a V or U) on their necks.
An Aesculapian snake can grow up to 2 metres long. (Image: Getty Images)
The Aesculapian snake species is believed to have three "thriving" populations across the UK which have descended from escapees.
One of them is located in Colwyn Bay (North Wales).
Researchers from Bournemouth University have recently conducted a study on the re-introduced Aesculapian snake and why they are thriving in the UK's chiller temperatures.
Radio trackers were implanted into 21 of the snakes and a team from the University monitored their movements over two summers (June to October 2021 and May to September 2022).
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The results of the study found that the Aesculapian snakes were climbing walls and entering buildings, hiding out in areas such as attics.
They also used garden compost bins for shelter and to incubate their eggs, BBC Countryfile reported.
The snakes also digested food or prepared to shed their skin as ways of keeping warm.
BBC Countryfile added: "The snakes appeared to coexist with suburban wildlife and there were no indications that their presence was affecting native species."