The call follows the discovery of a wounded cockatoo in a backyard in Le Hane Plaza, Caringbah, on January 4. The cocky had been shot in the chest by a slug gun.

The RSPCA is now investigating.

RSPCA inspector Ainslie Lund said the bird had suffered before it died.

"A post-mortem showed the slug from the gun entered the front of the bird, pierced its bowel and lodged in its back," she said.

"It was an extremely slow and painful death."

Ms Lund said there had been numerous incidents of birds being shot around the area during the past 12 months.

"It is a callous, deliberate attempt to kill the native wildlife," she said. "They [the offenders] knew what they were doing.

"Under the Animal Cruelty Act, this is aggravated cruelty with intent, which is the worst charge against an animal.

"But it is also a charge under the Crimes Act and carries a maximum penalty of $22,000 and two years imprisonment."

Anyone with information is advised to call the RSPCA on 9770 7555.