Four Kererū, or New Zealand pigeons, have been found shot dead at the Lake Mangamahoe Wildlife Sanctuary near New Plymouth.
The birds, which are protected under the Wildlife Act, are believed to have been shot on October 9, when a neighbour reported hearing gunshots in the area.
The Department of Conservation is on the hunt for those responsible.
Taranaki-based DOC Ranger Wayne Beggs said the birds were found near a picnic table around 1.5km from the reserve's main entrance.
"The birds have been x-rayed and bullet fragments found indicate the weapon used was either a high-powered slug gun or a small calibre rifle."
He said rangers have been investigating and DOC are now appealing for information for the public.
They say anyone who noticed anything suspicious in the area around that time should contact them.
Anyone who hunts Kererū can face a $100,000 fine or up to two years imprisonment.