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3,000 snails travel almost 5,000 km with a single objective

Call to Earth is a CNN editorial series committed to reporting on the environmental challenges facing our planet, as well as showing solutions to those challenges. Rolex’s Perpetual Planet initiative has partnered with CNN to raise awareness and educate about key sustainability issues and to inspire positive action.

(CNN) — A wooden box containing 1,000 adult snails and 2,000 young specimens set out on a 3,000-mile journey from a zoo in northern England to Bermuda last May.

The snails were neatly packed inside the box, along with damp handkerchiefs which helped keep them warm and green beans for food on board during the seven hour flight.

The box traveled alongside other regular shipments, with only a few labels distinguishing its rare and valuable contents:. The labels read “live animals”, “far east”, and “3,000 Bermuda land snails”. There was no indication that these animals, once released, could represent the future of an entire species.

The Little Bermuda land snails, as their name suggests, are native to the archipelago located in the North Atlantic Ocean. Over the past five decades, a series of threats have drastically reduced the populations of the species and it is now classified as critically endangered. In 2017, 60 of the remaining specimens were sent to Gerardo Garcia, head of ectotherms (cold-blooded species) at Chester Zoo, in an effort to save the species from extinction.

The snails have made a long journey from England to Bermuda.
(Credit: Chester Zoo)

García and his team, experts in the breeding of reptiles and small invertebrates, began to study the diet and the modes of reproduction of the enigmatic species. In the years that followed, the tiny snails began to multiply.

“When we started the Bermuda snail program at the zoo, we were on the verge of extinction for the species,” says Garcia. “Today we can say that they are in the process of recovery and that we are moving in the right direction.”

The recent release is the latest attempt to reintroduce this tiny species to its natural habitat. 1,000 snails were released on each of the islands – Trunk, Higg and Port – of Bermuda. This follows three previous versions, between 2020 and 2022, the results of which are still being tracked.

Only time will tell how successful the reintroduction will be, and Garcia suspects it will go at a snail’s pace. The species’ reproductive cycle is long and their size makes tracking difficult, as they are too small to carry an electronic tracker. But he and other scientists are hopeful, in part because of their success in reintroducing the species’ older cousin: the Bermuda land snail.

This creature – the size of a grape – was considered extinct for more than 40 years until, by chance, a man discovered one in an alleyway in Hamilton, the capital of Bermuda.

“It was 2014, and a member of the public walked into my office and opened his hand, and inside his hand was a snail shell,” recalls Mark Outerbridge, a wildlife ecologist at the Bermuda Department of Environment. “He said to me, ‘I think it might be an extinct species.'”

Scientists have reintroduced Bermuda's major and minor land snails to different islands in the archipelago. (Sandy Thin/CNN)

Scientists have reintroduced the large and small Bermuda land snails to different islands in the archipelago.
(Credit: Sandy Thin/CNN)

The solitary shell led to the discovery of a population, sparking a conservation effort. Outerbridge contacted Garcia – who had previously worked in Bermuda with skinks (a type of lizard) – and together they decided to ship 60 of the snails to Chester, where they could be studied and eventually bred.

Since then, more than 100,000 Bermuda land snails have been reintroduced to various locations in the archipelago, which Garcia considers one of the greatest examples of single-species reintroduction.

“They are doing very well: we see the animals settling, reproducing and spreading,” he says. In fact, the species does so well on its own that it thinks it no longer needs to be kept in a zoo.

The hope is that the smaller land snail will follow the slimy trail of the larger one. “We used the large Bermuda land snail as a surrogate, or the research surrogate, assuming that if they do well, the small Bermuda land snail will also do well,” says Outerbridge.

Killer peppers and chickens

But the long-term recovery of a species from such small numbers is difficult. Agriculture is not a panacea and must be combined with other conservation measures.

According to Outerbridge, major and minor land snails were threatened by predators such as flatworms, carnivorous snails and feral chickens, invasive species introduced to Bermuda by humans over the past 50 years (some on purpose, from others accidentally). For populations to thrive again, these threats must be reduced.

Gerardo Garcia (left) greets conservationist Mark Outerbridge upon his arrival in Bermuda with the box of endangered snails. (Sandy Thin/CNN)

Gerardo Garcia (left) greets conservationist Mark Outerbridge upon his arrival in Bermuda with the box of endangered snails.
(Credit: Sandy Thin/CNN)

During the early years of the Bermuda Land Snail Project, Outerbridge recalls, he felt pressure because, although the snails were multiplying in British laboratories, there was no safe place to release them. He and his great team have therefore worked hard to create a welcoming environment on the various islands where the reintroduction takes place. For example, on Trunk Island, they focused on eradicating invasive species such as Brazilian pepper, a garden plant introduced in the 1950s that outnumbered many local plants, and replanting native species such as hearts of palm and cedars. They have also introduced management plans to deal with chicken infestations.

“The islands have become life rafts for endangered species that we cannot control on the main island,” says Outerbridge.

Once the islands returned to what they were before the species declined, the team gave Garcia the go-ahead to start returning the snails.

Small snails, big impact

Garcia has long been a small-species advocate. At Chester Zoo, he works in a cluster of shipping containers outside the main zoo, away from the Sumatran tigers and Asian elephants that often attract visitors. The endangered reptiles, amphibians and invertebrates kept in the bins may not be quite as glamorous, but he insists they are no less important. These are some of the most endangered groups of species on the planet, and it is here that scientists study their biology, behavior and breeding habits in a controlled environment, with the aim of reintroducing all species into nature.

It is a small species which, according to experts, has an important role in the ecosystem.  (Credit: Chester Zoo)

It is a small species which, according to experts, has an important role in the ecosystem. (Credit: Chester Zoo)

When people ask Garcia why he goes out of his way to help creatures as small as Bermuda snails, his response is, “Why do we care about the species we have on the planet?

“Everyone, animals and plants, has a role to play,” he says. “Snails have many functions, one of which is to degrade materials. It’s part of the ecosystem, and if you remove that piece (then) the system doesn’t work.”

He hopes the work they are doing will help engage the public and send a strong message of optimism.

“We can really bring back a species that was on the verge of extinction,” he says.