Linda Cruickshank, who lives close to where the roo was found near Ballykeane Lane, said she regularly stopped by the side of the road on that part of Cadia Road to check for joeys in pouches of kangaroos hit by traffic.

Only on Sunday, Ms Cruickshank made the "very disturbing" discovery.

"Someone cut the ears off it with a knife .... they've clearly been cut off with a reasonably-sized knife," she said.

"It must have been done with a hunting knife."

Ms Cruickshank said she regularly stopped along that section of road to check dead kangaroos' pouches for joeys, which is what she'd done on Sunday.

"It's an area where they cross a lot, there's a reserve behind the Rural Fire Service HQ and they often get hit by cars and trucks along here," Ms Cruickshank said.

"I saw it was a male so wasn't going to have a joey but realised what happened to its ears."

Ms Cruickshank said she couldn't tell if the kangaroo had been hit by a car and then been mutilated afterwards or if it had been killed.

"It's very disturbing to find something like that," she said.

WIRES media officer John Grant said while it was difficult to give a definitive answer without a vet's assessment, he said ears were occasionally bitten off.

"Smaller predators such as foxes, raptors and even feral cats have been known to make a meal of soft tissue areas of a carcass such as the ears and can remove them quite cleanly," he said.

"However if these injuries are the result of human intervention it is not only a senseless act but if the animal was still alive it should be referred to the Police or RSPCA for investigation."