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

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

The release returns two species of land snails from Desertas Island to the wild. Before this, they were believed to be extinct; neither species had been detected for a century.

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

The snails were taken to zoos in the UK and France, including Chester Zoo, where a home was created for them in a converted shipping container.

The tiny mollusks are native to the mountainous, windswept island of Deserta Grande, just southeast of Madeira. Their habitat has been destroyed by rats, mice and goats that were brought to the island by humans.

All of these invasive predators were thought to have eaten the small snails to extinction. Then, a series of conservation expeditions, between 2012 and 2017, demonstrated the opposite.

Conservationists discovered only 200 surviving individuals on the island.

It was believed that these snails were the last of their kind, so they were collected and taken into captivity.

At Chester Zoo, the conservation’s scientific team built a new home for 60 of the prized snails. Food, vegetation and suitable conditions were recreated in miniature habitat tanks.

1,329 baby snails, raised at the zoo, have been marked with identification points (using non-toxic pens and nail polish) and transported back to the wild for release.

“(It’s a) color code,” said Dinarte Teixeira, a conservation biologist at the Madeira Institute for Nature and Forest Conservation. “This will allow us to detect them and track where they disperse, 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.

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

“If all goes as well as we hope, more snails will follow next spring. It’s a great team effort that shows that it is possible to turn the tide for highly threatened species.”

“These snails are a very important part of the natural habitat (on the islands where they come from),” explained Heather Prince of Chester Zoo. In addition to being food for other native species, he explained, snails decompose organic matter and provide nutrients to the soil.

“They help plants grow. That’s all down to the little guys: the insects and snails that so often go unnoticed.”