THE number of wedge-tailed eagle deaths at a Tasmanian windfarm may be higher than officially acknowledged.

Up to six of the endangered eagles may have been killed in the past year after being struck by turbines at the Woolnorth windfarm in the far North-West.

Windfarm operator Roaring 40s, jointly owned by Hydro Tasmania and China Light and Power, puts this year's official death toll at four.

However, a further two eagles found dead at the windfarm this year are not included in the tally.

It is believed autopsies on these two dead birds failed to prove conclusively they were turbine victims.

The birds, one believed to have died in recent months and the other up to a year ago, may have been roadkill.

However, wedge-tailed eagle carer Craig Webb said the low level of road traffic at the remote Woolnorth windfarm would suggest the deaths were more likely caused by the turbines.

Mr Webb, who operates Raptor and Wildlife Refuge of Tasmania at Kettering south of Hobart, said the far North-West eagle population could not sustain the current rate of mortality.

"Besides the science of it and the impact on the species, I can't help feel for the individual birds being killed. It's just sad," he said.

If the two dead eagles were killed by turbines it takes the overall number of deaths to seven since the windfarm began in 2002.

Roaring 40s chief executive Mark Kelleher last month said he was upset by the death toll and serious efforts were being made to reduce it.

Mr Webb said he was impressed by the efforts of Roaring 40s to address the problem but stressed the death toll must not be allowed to escalate.

Wedge-tailed eagles in Tasmania are listed as an endangered species.

They have been isolated for 10,000 years from their mainland counterparts and are a separate sub-species.

The Department of Primary Industries and Water website says only about 130 pairs successfully breed each year in the state.