More than 1,300 critically endangered snails have now been released into the wild, thanks to specialists at Chester Zoo.

The Desertas Island land snails were rescued from the edge of extinction, with help from a team of conservationists from the UK and Madeira.

They were thought to have disappeared altogether, having not been recorded living for more than 100 years.

However, experts recently rediscovered tiny populations of two species of the snail.

Each species consisted of fewer than 200 surviving individuals, on an isolated island called Desertas Grande in the Madeira Archipelago in the North Atlantic Ocean. 

The snails were believed to be the very last of their kind on the planet.

Sixty were flown to Chester Zoo, where their invertebrate experts worked to establish a unique breeding programme in a last-ditch attempt to boost numbers and save the species.

The Desertas Island land snails were thought to have disappeared altogether, having not been recorded living for more than 100 years (Image via: Chester Zoo)

Specialists at the zoo managed to create the perfect conditions for the snails to thrive and made a breakthrough.

They successfully bred both species for the first time ever in human care.

With a blueprint in place and the population beginning to boom, snails were sent from Chester to two other leading conservation zoos in Europe: Bristol and Beauval, France.

Now, 1,329 snails raised in Chester have returned to Bugio Island as part of a reintroduction.

The small island has been specially selected as the main threats which almost wiped out the snails have been removed.

Invasive goats, rats and mice, which have decimated the landscape, have been eradicated, while work to restore habitat on the island to its former glory has been carried out. 

Dr Gerardo Garcia, Head of Ectotherms at Chester Zoo, said: "When the snails first arrived in Chester, the very future of the species was in our hands.

"It was a huge responsibility to begin caring for them and we acknowledge the trust the IFCN, as a representative of the Madeira Government, placed in us.

The Desertas islands are the only place in the world where the snails can be found (Image via: Chester Zoo)

"As a zoo conservation community, we knew nothing about them.

"They'd never been in human care before and we had to start from a blank piece of paper and try to figure out how to create an environment in which they could flourish, and encourage them to breed.

"These snails really were on the edge of extinction and the fact that we've now been able to give them a chance of making a comeback is testament to the efforts of many people, including our highly dedicated and skilled zookeepers who have spent countless hours caring for every individual snail.

"The ultimate aim is that the snails go on to thrive in their new home and the critical human interventions we're making through reintroductions and reinforcements are no longer needed."

Heather Prince, an invertebrate specialist at the zoo, has been working on land snail conservation for more than 12 years.

She said: "within a few months we were able to crack the breeding of the Desertas land snails, successfully breeding multiple generations.

"This was key because it meant we could then support other zoos and establish a network, breeding them in the substantial numbers needed to have a chance of saving the species."

Each of the snails reintroduced on Bugio has been individually marked with a colour code using a tiny amount of infra-red paint.

This will allow specialists to track where they disperse, how much they grow, how many survive and how well they adapt to their new environment.

If successful, many more snails will join them to help give the species a further boost.

You can learn more about Chester Zoo's conservation efforts here.