Native bird populations are under threat from exotic birds that have escaped from captivity, the Northland Regional Council says.
The council asked for any sightings of Indian ring-necked parakeets, rainbow lorikeets or sulphur-crested cockatoos in the wild to be reported.
Council biosecurity manager Don McKenzie said the exotic birds threatened native species by competing for food, taking nesting places and introducing diseases.
"Lorikeets and parakeets can also become significant agricultural pests of some cereal and fruit crops," he said.
McKenzie said a number of Indian ring-necked parakeets in particular have been reported missing recently.
Indian ring-necked parakeets are native to India and Africa, are about 40cm long and could be green, yellow, grey or blue.
"Most males have a distinctive thin black line around their necks. Females and young birds don't have this marking."
The council was aware of at least eight pet exotic birds loose in Northland.
"These birds are good breeders and can establish populations quite quickly so it's important to act fast before they breed and spread to other areas," McKenzie said.
"We need people to tell us if they have accidentally set their birds free or have seen them at large and urge them to do so as soon as possible and we'll do our best to retrieve them or locate their owners."
All three bird species were listed as "unwanted organisms" by the Ministry for Primary Industries.
It was legal to keep, sell and breed all three species, but not to release them into the wild.
Rainbow lorikeets come from Australia, are around 30cm long with a distinctive blue head and belly and look similar to rosellas.
Sulphur-crested cockatoos, another Australian native, are large with distinctive yellow crest feathers.
McKenzie said the three bird species were common in captivity and wild populations usually established from caged birds that escaped.
"Clipping their wings is recommended as a precaution and pet owners who no longer want the birds should contact a local bird club or pet store to rehome them."
McKenzie asked anyone who loses a ring-necked parakeet, and a rainbow lorikeet or a sulphur-crested cockatoo, or anyone who sees one in the wild, to call the council on 0800 002 004.