There has been an increase in sightings of so-called "angry birds'' around Auckland, the Ministry for Primary Industries says.
The ministry is aiming to eradicate red-vented bulbuls, birds from Asia it says threaten the country's crops and native birds.
The "angry birds'' label comes from their likeness to birds from the game of the same name, and the ministry reckons it aptly reflects their nature too.
"The red-vented bulbul is one of the most invasive bird species in the world and in New Zealand is listed as an unwanted organism under the Biosecurity Act 1993,'' said ministry response manager Jaap Knegtmans.
"We think there are at least five in Auckland. It's difficult to know exactly how many there are because they are quite mobile, moving large distances around the city.''