Image copyright Wellington Zoo

New Zealand's only resident pelican has been put down after living at Wellington Zoo for nearly 40 years.

Wellington Zoo said Lanky had arthritis and had been struggling to support his own weight. He had stopped eating or taking his medicine.

He was euthanised "in his best interests", the zoo said in a statement on Monday.

An Australian pelican, Lanky was the longest living resident of Wellington Zoo, arriving there in 1978.

"Lanky had regular medical examinations and we were able to manage the arthritis in his ankles with pain relief and anti-inflammatories, but his lameness increased over recent months," said the zoo.

His recent refusal to eat was in contrast to his appetite in better days, when he consumed a kilo of fish a day, sometimes "sneaking food off his neighbours" in his favourite haunt of Monkey Island, said Senior Keeper Phil Wisker.

Pelicans from Australia do occasionally drop into New Zealand but Lanky was the only one permanently in the country.

He originally arrived in Wellington from Australia's Adelaide Zoo, after being rescued with three other wild pelicans from a local drought, the zoo said.

"All of us here at the Zoo are sad to see Lanky go, as he has been a real character and much loved by everyone who has cared for him over the last decades," it said.