Chester Zoo’s conservationists have bred 300 near‑extinct tiny snails and introduced them back into the wild.

Only 21 Madeiran land snails were found clinging to a rock on Portugal’s Bugio Island; they were believed to be the last of their kind.

Experts at Chester Zoo braved treacherous conditions, climbing cliffs to return the snails to their natural home in the Madeira archipelago, remote in the Atlantic Ocean.

The Madeira government asked Chester Zoo to help with this snail conservation effort.

Conservationists scrambled from the water up a cliff face in the dark, searching for cracks in the rocks where the snails could be safely left.

Tamas Papp, assistant team manager for invertebrates at Chester Zoo, said, “We knew we had one shot to save them. If we missed this chance, that was it: they were gone.”

“It might be the trickiest reintroduction we’ve ever done,” Papp added. “We had a short window due to rough weather, and there’s no jetty on the island. We had to jump straight into the water, climb out, put helmets and harnesses on, and start scrambling up the cliff face.”

The snails, measuring no more than a third of an inch (8 mm), are important as they eat vegetation and enrich the soil.

They will be monitored as they settle back into the wild.

Bugio Island in the Atlantic, to which the snails have been returned after a breeding programme