Up to eight captive-bred Tasmanian devils released as part of a re-wilding program have been killed on the island's roads.
The latest four to die were set free last week in the Forestier Peninsula woodlands east of Hobart, after being bred at the Devil Ark sanctuary near Newcastle.
The animals died on the peninsula's Tasman Highway, a winding forested tourist route where they had travelled up to 15 kilometres from their release site. Microchip checks confirmed the identities of the devils, which were part of a precious population of animals living in the wild free of the devil facial tumour disease which is wreaking havoc on the species.
"It is obviously very sad, and we certainly can't view it as anything but a setback," said Devil Ark's operations manager, Mike Drinkwater.
"But when we're talking true re-wilding, roadkill is going to be an ever present danger," he said. "It's a problem for animals right across this country."
The eight came from a total of 59 healthy animals released at two Tasmanian sites to combat devastating losses of the animal to the transmittable cancer known as devil facial tumour disease.
The first four died within days of each other in September at Narawntapu National Park in Tasmania's north.
Another spate of deaths after the second release indicated the animals that travelled furthest from their release site may be more likely to die on roads, Save the Tasmanian Devil Program director Howell Williams said.
Dr Williams agreed it was possible more devils had been hit by vehicles and were unseen in roadside checks. But he said it was vital to keep the re-wilding program going.
Over the past 20 years the deadly facial cancer had wiped out most devils in Tasmania, with some populations dealt 95 per cent losses.
Small numbers persisted in the wild and Dr Williams said these were becoming inbred.
"They are not ecologically functional," he said."They might as well be extinct in the wild. So we are trying to boost the population."
More than 600 devils live in a captive insurance population in Tasmania and around Australia, with strong numbers breeding at Healesville Sanctuary outside Melbourne and the Devil Ark at Barrington Tops.
"There is no textbook on how to release Tasmanian devils," Dr Williams said. "Obviously we are doing everything we can to hone our technique."
Attempts have been made to keep the animals in their release zones by distributing food for them.
The devil program will considers methods of keeping animals in a local area after release, so they could settle down, he said.
The Tasmanian government is issuing urgent pleas to drivers to slow down at night.
