A "weird puking bird" with a bizarre mating dance has won New Zealand's annual avian beauty contest, triumphing after British comedian John Oliver launched an unlikely global campaign.

The unfancied Australasian crested grebe soared to an unexpected victory in the Bird of the Century ballot on Wednesday, backed by voters from far-flung cities including Tokyo, London, and Paris. 

Oliver used his popular television show to meddle in New Zealand's beloved competition, urging viewers to back the species more commonly known by its Maori name "puteketeke".

Baffled organizers were soon in a flap as tens of thousands of votes poured in from 195 countries, briefly crashing counting systems.

With a striking plumage of black, white and brown, New Zealand's online bird encyclopedia celebrates the water-loving puteketeke as a "majestic and distinctive" species.

Oliver, meanwhile, less charitably dubbed it the "weird puking bird". 

Puteketekes are known for eating their own feathers in an effort to trigger their gag reflex and throw up parasites, said competition organizer Nicola Toki from the conservation group Forest and Bird. 

"Puteketeke began as an outside contender, but was catapulted to the top spot thanks to its unique looks, adorable parenting style — and propensity for puking," Toki said.

They are also known for a strange and elaborate mating ritual which they perform with gusto but limited success — it is believed New Zealand's puteketeke population has dwindled below 1,000. 

It involves enticing a potential mate with weeds dangling from their beaks before chest bumping them and engaging in a chorus of chirps that experts have called the "growling cat display". 

"I have never identified with anything more," Oliver said.

'Alarmingly aggressive campaign'