Up to 20 protected wedge-tailed eagles have been "possibly shot" or poisoned and then dumped in parkland in Victoria.
The environment department says the latest discovery of four carcasses in the Black Range State Forest added to more than a dozen bodies found in the Yea area over the past few years.
"Because of the location of the carcasses, we believe that they have been intentionally destroyed, possibly shot," environment department spokesman Leigh Murray said in a statement on Wednesday.
"Last year we located eight eagles within a 25-metre radius of each other, that had been poisoned."
He said the nation's largest bird of prey were sometimes a target for the threat they pose to newborn lambs.
But he says the eagles more often eat roadkill and other dead animals.
As the wedge-tailed eagle is a legally protected species, the penalties for hunting or destroying it can be up to half a year in jail and a fine of almost $8000.
Information about those responsible can be provided anonymously to the environment department's customer service hotline or to Crime Stoppers.