For decades conservationists believed Bermuda’s endemic land snail, Poecilozonites bermudensis, was extinct.

They feared it had become a victim of invasive predators.

But now, around 40 years after its last sighting in the wild, a healthy colony of these snails has turned up in the heart of Hamilton in a damp and overgrown alleyway.

The discovery has amazed conservationists in Bermuda.

And steps are now being taken to protect the habitat and re-establish the uniquely Bermudian small snail on the Island.

Mark Outerbridge, Conservation Service’s Wildlife Ecologist, told The Royal Gazette: “It really is an incredible story.

“This is a unique genus of snail, found nowhere else in the world, and for years we have thought it has been extinct.

“For it to be found in Hamilton is unbelievable. It’s the last place you would imagine that a small colony of rare snails would be discovered.

Dr Outerbridge added: “But it seems that this small group has been protected by their urban isolation.

“The fact that there was so much concrete around them probably saved them from the predators that we believe killed the vast majority of the population Island-wide.

“This is another example of yet another endemic that we thought had gone extinct but has not, very much like the Cahows, which were thought to have disappeared during the 1600s, until they turned up again in 1951.

“To me what is really exciting is where they were found. It blew my mind.

“People have been looking for these snails for decades and here they are surrounded by concrete and air conditioners living in a 100 square foot alleyway in Hamilton.”

The last recorded sighting of this endemic land snail was made in the early 1970s by Stephen J Gould.

The well-known paleontologist had done his PhD as a young man on the Island and recorded them as being plentiful throughout the country.

But when he returned to Bermuda in the early 1990s their numbers appeared to have taken a dramatic plunge, to the point that he could no longer find one.

Dr Outerbridge added: “A lot of what we know today about these animals comes from Dr Gould’s work.

“He came down here as a deckhand on a ship originally and was fascinated by the evolution that had happened to these snails in Bermuda.

“He returned to the Island to do his PhD on them.

“He was still working with these species in the late 1960s and early 1970s.

“But suddenly it seemed that the snails, which had once been plentiful, completely died out.

“Dr Gould put it down to the introduction of predatorial snails that were deliberately brought to Bermuda to control the edible garden snail — another introduction that was proving a pest. One of the sad sides to this story is that Dr Gould is not alive now to hear that this animal still remains in the wild.

A survey conducted in 1988 by two US scientists in Bermuda could find no living trace of Poecilozonites bermudensis.

And later studies in 2000, 2002 and 2004 seemed to confirm that the animal was extinct.

Furthermore, it was discovered that the population of another smaller endemic snail, Poecilozonites circumfirmatus, was rapidly declining.

As a result a lifeboat project was arranged and the much smaller snail was sent to London Zoo where it has been saved from extinction.

Plans are now afoot to protect the colony of Poecilozonites bermudensis in Hamilton and look at possible spots to translocate the species around the Island to reestablish it.

Dr Outerbridge said: “We have a Canadian snail expert who is coming to Bermuda in the new year to help us look at the potential sites where the Poecilozonites bermudensis could be translocated.

“For the time being we have gathered a small population from the Hamilton alleyway and are looking after them at Conservation Services.”