Chester Zoo Returns Hundreds of Critically Endangered Snails to Restored Atlantic Island

A conservation breeding program at Chester Zoo in England has successfully reintroduced more than 300 Desertas Island land snails (Geomitra coronula) to their native habitat on Bugio Island in the Madeiran archipelago. The species had been reduced to a known wild population of just 21 individuals, found clinging to life beneath a single rock, before biologists from ZooParc de Beauval in France requested the zoo's intervention.

According to Tamas Papp of Chester Zoo's Invertebrates Team, the entire global population of the species could fit inside a single petri dish at the time of rescue. The zoo undertook a rapid breeding effort, producing hundreds of descendants from the original 21 snails. Each snail measures approximately 8 millimeters, roughly the size of a pea.

Before the reintroduction, Madeiran Government conservationists removed invasive goats, mice, and rabbits that had denuded the island's vegetation and preyed on the snails. The habitat restoration also aimed to protect at-risk seabird populations. The island has no natural sources of drinking water, which had driven the invasive mice to target the snails as a moisture source.

The release operation involved significant logistical challenges. Papp personally transported the snails to Bugio Island during a narrow weather window, as rough seas and the lack of docking facilities complicated access. The team traveled at night using red-spectrum torches to locate suitable rock crevices for placement, avoiding disturbance to the island's light-sensitive seabirds.

Chester Zoo is now working to establish a broader network of breeding centers, including facilities in Madeira, to secure the species' long-term survival. The zoo has issued a call to the European network of conservation zoos for participation, reporting a positive response. Plans include transferring animals to build a genetically healthy, secure population across multiple institutions.

Conservationists emphasize that despite their small size, the snails play an important ecological role by consuming vegetation and enriching soil. Their recovery is expected to support the broader restoration of fragile island ecosystems in the archipelago.