AUSTRALIA'S biggest wind farm in north-west Tasmania has become a "black hole" for endangered wedge-tailed eagles.

The 62-tower Woolnorth farm has killed up to 18 of the island's endangered subspecies of the wedge-tail in its giant rotor blades.

Despite their acute vision, the eagles are failing to pick out turbine blades with tips that can rotate at 300 kmh, according to Eric Woehler, chairman of Birds Tasmania.

"Eagles evolved in a landscape without wind farms," Dr Woehler said. "They just don't see the blades. The researchers there are finding that they are dying not only in the downsweep, but in the upsweep of the blades."

Woolnorth's owners say 11 of the birds have died, but Dr Woehler said Birds Tasmania believed up to 18 may have been fatally injured by the rotors, which are at their most dangerous in specific north- east wind conditions.

"It's killing eagles that were resident and drawing more in from the surrounding areas, so it will continue to be a black hole for these birds," Dr Woehler said.

There are an estimated 1500 Tasmanian wedge-tails, which are a larger bird than their mainland cousin.

Other threats they face in the state include shooting, poisoning and overhead line strikes.

The wind farm is operated by Roaring 40s, a partnership of Hydro Tasmania and China Light and Power.

Dr Woehler said observers at the site watched for eagles and could halt specific rotors when the birds were nearby.

"But since last year when the final stage of the farm was commissioned there have been an additional three deaths," Dr Woehler said.

The public relations manager for Roaring 40s, Josh Bradshaw, said the company was continuing to work closely with the State Government and Birds Tasmania to investigate further measures to reduce the risk of avian collision.

"There have been no recent incidents involving wedge-tailed eagles at the Woolnorth wind farms," Mr Bradshaw said.