By Nell Lewis
CNN.com
6/22/2023
Last month a wooden crate containing 1,000 adult snails & 2,000 juveniles embarked on a 3,000-mile journey from a zoo in the north of England to Bermuda.
The snails were carefully packed inside the crate, alongside wet tissues that helped maintain the temperature during the 7-hour flight, & green beans for an in-flight meal.
The box traveled alongside regular cargo, with just a few labels to distinguish its precious & unusual contents: “Live Animals,” “This End Up,” & “3,000 lesser Bermuda land snails.” There was nothing to indicate that these animals, when released, could represent the future of an entire species.
Lesser Bermuda land snails, as the name suggests, originate from the archipelago in the North Atlantic Ocean, but a number of threats over the last 5 decades have reduced populations of the species significantly & it is now classified as critically endangered. In 2017, 60 of the remaining individuals were sent to Gerardo Garcia, head of ectotherms (cold-blooded species) at Chester Zoo, in an effort to save the species from extinction.
Garcia & his team, experts in breeding small reptiles & invertebrates, began studying the diet & breeding patterns of the enigmatic species. In the years that followed, the tiny snails – about the size of a garden pea – started to multiply.
“When we started the program with the Bermuda snails at the zoo, we were just on the edge of extinction of the species,” says Garcia. “Today, we can say that this is a process of recovery – we’re going in the right direction.”
The recent release is the latest attempt to reintroduce this diminutive species to its native habitat, with 1,000 snails released on each of Bermuda’s Trunk Island, Higg’s Island & Port Island. It follows 3 previous releases between 2020 & 2022, the results of which are still being monitored.
Only time will tell how successful the reintroduction will be, & Garcia suspects it might move at a snail’s pace. The species’ reproductive cycle is long, & their size makes them hard to survey as they are too small to carry an electronic tracker. But he & other scientists involved are hopeful, partly due to the success they have had in reintroducing the species’ larger cousin: the greater Bermudan land snail.
This creature – similar in size to a grape – was thought to be extinct for over 40 years, until, by chance, a man discovered one in an alleyway in Hamilton, Bermuda’s capital.
“It was 2014, & a member of the public walked into my office & opened up his hand, & inside his hand was a snail shell,” recalls Mark Outerbridge, wildlife ecologist for Bermuda’s Department of Environment. “He said, ‘I think this may be an extinct species.’”
The lone shell led to the discovery of a relic population, which sparked a conservation effort. Outerbridge approached Garcia – who had already been working in Bermuda on skinks (a type of lizard) – & together they decided to send 60 of the snails to Chester, where they could be studied & ultimately bred.
Since then, more than 100,000 greater Bermuda land snails have been reintroduced to multiple locations on the archipelago, which Garcia believes is one of the largest examples of a single species reintroduction.
“They’re doing great – we see that the animals are established, breeding & spreading,” he says. In fact, the species is doing so well on its own, he believes it no longer needs to be bred in a zoo environment.
The hope is that the lesser land snail will follow the greater’s slimy trail. “We’ve been using the greater Bermuda land snail as the surrogate, or the research proxy, assuming that if they do well, the lesser Bermuda land snail will do as well,” says Outerbridge.
Pepper plants & killer chickens
But the long-term recovery of a species from such low numbers is complicated. Breeding is not a silver bullet, & it needs to be done in unison with other conservation actions.
Both the greater & lesser land snail species were originally threatened by predators such as flatworms, carnivorous snails, & feral chickens – invasive species that were introduced to Bermuda by humans in the last 50 or so years (some on purpose, others accidentally), according to Outerbridge. For populations to thrive again, these threats need to be reduced.
In the early years of the greater Bermuda land snail project, Outerbridge remembers feeling the pressure of this: the snails were multiplying in the labs in the UK, but there was nowhere safe for them to be released. So he & his wider team worked hard to create a welcoming environment in the various islands where reintroduction is taking place. For instance, in Trunk Island, they have focused on eradicating invasive species such as the Brazil pepper, a garden plant introduced in the 1950s that has out competed many local plants, & replanting native species such as palmetto & cedar trees. They have also introduced management plans to deal with chicken infestations.
“They (the islands) have really become our life rafts for species that are becoming threatened in ways that we can’t control on the main island,” says Outerbridge.
Once the islands were restored to close to how they were before the species’ decline, the team gave the thumbs up to Garcia to start shipping the snails back to the islands.
Small snails, big impact
Garcia has long been a champion of small species. At Chester Zoo, he works from a cluster of shipping containers tucked outside of the main premises, away from the Sumatran tigers & Asian elephants that visitors usually flock to. The endangered reptiles, amphibians, & invertebrates kept in the containers may not be as glamorous, but he insists they are no less important. These are some of the most threatened groups of species on the planet, & it’s here that scientists study their biology, behavior, & breeding habits in a controlled environment, with the goal of reintroducing all the species back into the wild.
When people ask Garcia why he goes to such lengths to help creatures as small as the Bermuda snails, his response is: “Why do we bother about any species we have on the planet?”
“Every single one, animals & plants, has a role to play,” he says. “Snails have many roles, one of them is degrading materials. That is part of the ecosystem, & if you remove that piece (then) the system is not working.”
He hopes that the work they are doing will help to engage the public & send a strong message of optimism.
“We can pick up a species that really was on the edge of extinction & we can turn it around,” he says.
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