A snake species has returned to the wild after a 10,000-year hiatus, having started breeding in the wild after escaping from a zoo in Wales.
The Aesculapian Rat Snake is a non-venomous reptile that can reach up to 6ft in length.
It was once native to Britain before the last Ice Age, but is now more commonly found in southern Mediterranean and Balkan countries.
In the 1960s, they were imported from Italy by Robert Jackson, the founder of the Welsh Mountain Reptile Zoo in Conwy.
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In the early 1970s, baby snakes were found in the zoo grounds – initially believed to be grass snakes due to their yellow markings, but later confirmed as Aesculapian Rat Snakes, which had started breeding and slowly spread beyond the zoo.
Bangor University PhD student Tom Major, who has been studying the snakes for five years, says the species now has a stable population in the Colwyn Bay area.
Major said they have a ‘limited’ range, are reluctant to cross over roads and are struggling to find prey – typically eating rodents up to the size of rats.
Speaking to NorthWalesLive, he said: “We found a snake yesterday that was born around September 2018 and that weighed eight grams in 2019.
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“Three years later, it weighed 15 grams – about the same as an HP pencil.
“Even allowing for six months of hibernation each year, and the cooler climate, it’s an extraordinarily slow growth rate. It suggests it might have eaten just once or twice in the past three years.”
Aesculapians can reach up to two metres in length in southern Europe, making them one of the continent's largest snakes.
In colder North Wales, however, Major believes they are unlikely to grow much beyond 1.5 metres - although this still makes them Britain's longest snakes.
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After beginning with field surveys, Major started radio tracking nine snakes last year, and plans to repeat the exercise this summer.
“We learnt they have a limited range, moving up to 500m per day, and are often constrained by things like roads,” he said.
“They spend long periods hidden in hay bales and in the walls of buildings.”
Major said people needn’t be alarmed if they spot a snake, adding: “On the Continent the snake co-exists with all other species, including animals you find here such as badgers, stoats and domestic cats.
“For a naturally balanced ecosystem, diversity is usually a good thing. It is used to living alongside humans and there is little or no evidence of it causing any harm.”
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In spite of this, the Aesculapian Rat Snake is considered a ‘Management Priority Species’ for Wales, which means the Colwyn Bay population has been monitored since 2004 so that ‘rapid response can be taken if necessary’, the North Wales Wildlife Trust said.
If you find an Aesculapian snake in the Colwyn Bay area, report it to Tom Major at [email protected].
Jess Hardiman