X-rays revealed a shattered wing joint where shotgun pellets were found.
Based on veterinary advice, the bird was euthanised.
“The bird was quite underweight so we believe it may have been injured for several days before it was found,” Langman said.
Royal spoonbills are protected under the Wildlife Act, and hunting or killing a protected species can result in a fine of up to $100,000 or two years in prison.
Fish & Game Auckland / Waikato chief executive David Klee said shooting protected birds was unacceptable.
“Hunters must clearly identify their target and there is no excuse for shooting a royal spoonbill, which bears no resemblance to waterfowl species that can be legally hunted.
“Our Code of Conduct states licence holders must ensure they can accurately identify and distinguish game birds from protected species.
“We have very few incidents like this, but it can bring everyone in the hunting community into disrepute.”
Fish & Game compliance officers have been working alongside DoC staff since the opening of the duck hunting season to ensure hunters are following the rules.
A team is on call at weekends and will investigate any incidents.
Royal spoonbills are a mobile species found in increasing numbers around New Zealand, and are identifiable through their unique bill, long black legs and white plumage.
They feed by distinctively swishing their bill from side to side, while wading through shallow water.
People who have information about the incident in which the bird was shot are urged to call 0800 DOC HOT, or email wildlifecrime@doc.govt.nz, and quote case number CLE-9126.