Breeders shellshocked as snail trail goes cold

Eight hundred rare giant snails – one-seventh of an entire species – have been accidentally frozen to death in New Zealand after conservation officials failed to notice that a temperature probe in a cool room was broken.

The incident is an embarrassment for New Zealand, a UN-designated biodiversity hotspot. The Powelliphanta augusta snails – carnivorous land snails which grow to the size of a fist and suck worms out of the ground – are endangered.

The casualties were part of a captive breeding programme initiated after the entire Powelliphanta population – about 6,000 snails – was moved from the Stockton Plateau, on the South Island, to make way for an open-cast coal mine. A total of 4,000 have been released in another part of the mine, while 1,600 were being kept in chiller units in a Department of Conservation facility in Hokitika. John Lyall, the regional technical support manager, said staff were devastated. But the conservation group Forest & Bird said it highlighted the folly of moving native animals from their habitat. "This tragedy was entirely avoidable," said a spokeswoman, Nicola Vallance.

The snails were supposed to be kept at 10C, but the temperature plunged to zero. The fault in the probe was not immediately picked up because it happened during a public holiday last month.