By Mark Kinver
Science and nature reporter, BBC News
A wildlife group says a species of snail that almost halted the building of the controversial Newbury bypass has become extinct on a nearby site.
The snail's demise is a worrying sign, campaigners say (Image: Roger Key/English Nature)
Buglife said no Desmoulin's whorl snails were left in the area where they were relocated in 1996 to allow the new 30-mile route to be built.
It blames the creatures' demise on the location not being properly maintained.
Environmental watchdog English Nature said the snails' decline was not a result of the habitat's condition.
It said such snails could experience large swings in population size and argued that the animals' true status was not easy to judge at this stage.
The species Vertigo moulinsiana came to the nation's attention during one of the highest-profile anti-road campaigns of recent years.
Green campaigners dug tunnels and occupied trees at the site of the proposed bypass to try to stop the highway going ahead.
The snails themselves were the subject of a legal row; the planned route went through marshes where the molluscs, protected under international legislation, lived.
Hundreds of protesters camped in nearby woodlands
A compromise was eventually agreed that saw the creatures' habitat being moved to a specially constructed "translocation site" so that the road builders could move in.
"What happened was that the pipes that fed the water the snails needed on the translocation site became silted up; hence, the fen dried out and this is when the snails got into trouble and became extinct," explained Matt Shardlow from the invertebrate conservation group Buglife.
"The site could sustain the snails but it is a high-maintenance location. It is high maintenance because it is artificially created and unless you keep it going then troubles begin," he told BBC News.
'Boom and bust'
English Nature conservation officer Russ Money said there had been problems with the site, but this was a result of vandalism and low water levels.
"It is quite a dangerous inference to suggest the decline of the snails we have seen at the translocation site is the result of maintenance issues we have had there," he said.
"We have also seen massive declines in populations in quite a number of our protected sites which have no relationship with the bypass."
He added that there were healthy populations of the invertebrate in nearby locations outside the protected area.
Roger Key, a senior invertebrate ecologist for English Nature, called the snails a "boom and bust" species and said it was far too early to describe them as extinct.
"What we have actually found is that an area's population suddenly disappears then reappears in much greater numbers.
Dr Key added that the snails were more plentiful than previously thought: "At the time of the inquiry into the Newbury bypass, everyone thought it was a really rare species; but when we started looking, we found more and more.
"They are 1.5mm long and live in deep swamp litter, so they are likely to have been under-reported," he suggested.
Last October, the Environment Agency carried out a series of nine surveys in the area as part of its obligations under the EU's Habitat directive.
The survey at the translocation site did not find any snails, but a spokesman for the agency said it was not possible to blame this on the level of maintenance.
"One of the factors could be drought or it could have been something else; there could be a whole range of reasons for this," the spokesman added.
Buglife's Matt Shardlow said the Newbury bypass was an example of a bigger question political leaders had to address.
"If the government instead of budgeting for 30 miles of road put that money into nature conservation then we could sort out the loss of species and habitat.
"At the moment, we are facing budget cuts," he said. "So, rather than actually having more money to look at biodiversity, we are looking at less money; hence in the future we are not going to even know if these European protected species are in trouble."