Why 1,329 tiny snails are released on a remote island

More than 1,300 pea-sized, endangered snails bred in a zoo have been released to wander (very slowly) on a remote Atlantic island.

The release brings two species of Desertas Island land snails back into the wild. They were previously considered extinct – neither species had been seen for a century.

When a team of conservationists found a small surviving population on the rocky cliffs of Deserta Grande Island near Madeira, they launched a rescue operation.

The snails were taken to zoos in Britain and France, including Chester Zoo, where they were given a home in a converted shipping container.

The tiny molluscs come from the windswept mountain island of Deserta Grande, southeast of Madeira. The habitat there has been destroyed by rats, mice and goats brought to the island by humans.

All of these invasive predators were thought to have eaten the tiny snails to extinction. Then a series of conservation expeditions between 2012 and 2017 proved otherwise.

Conservationists discovered only 200 surviving individuals on the island.

These snails were believed to be the last of their kind, so they were collected and taken into captivity.

At Chester Zoo, the conservation team has created a new home for 60 of the valuable snails. Proper food, vegetation and conditions were recreated in miniature habitat pools.

1,329 snail offspring bred at the zoo have now been marked with identification points using non-toxic pens and nail polish and transported back into the wild for release.

“(It’s a) color code,” said Dinarte Teixeira, a conservation biologist at the Madeira Institute for Conservation and Forests. “This allows us to detect and track them, where they spread, how much they grow, how many survive and how well they adapt to their new environment.”

A wild refuge for snails has been restored on Bugio, a smaller neighboring island in the Ilhas Desertas (Desert Islands) archipelago.

Bugio is a nature reserve and invasive species have been eradicated there.

Chester Zoo’s Gerardo Garcia said the reintroduction was “an important step in a species recovery plan”.

“If things go as well as we hope, more snails will follow them next spring. It is a great team effort that shows that it is possible to change the situation for critically endangered species.”

“These snails are such an important part of the natural habitat (on the islands they come from),” explained Heather Prince of Chester Zoo. She explained that in addition to providing food for other native species, snails break down organic matter and add nutrients to the soil.

“They help plants grow. It all depends on the little guys – the insects and snails that are so often overlooked.”