The lesser frigatebird weighed just 469 grams when it arrived at the bird rescue centre.

Not only did Cyclone Gita leave destruction as it passed through New Zealand, it also left behind a rare bird.

Green Bay NZ Bird Rescue Centre in West Auckland is rehabilitating a young lesser frigatebird.

Trustee Miriam Whelan said the bird was usually found in places with warmer climates such as Fiji and Tahiti.

"There's been very, very few sightings ever in New Zealand," Whelan said.

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"We think it was probably Cyclone Gita that brought it in."

SUPPLIED Miriam Whelan says the bird is more alert, eating and beginning to flex its wings.

Whelan said the frigatebird was found in a remote location on Muriwai Beach about two weeks ago.

She said it was "severely underweight" at 469 grams.

"It probably wouldn't have survived much longer without food," Whelan said.

SUPPLIED Frigatebirds are extremely rare visitors to New Zealand, Miriam Whelan says.

"They get to a point where they don't have enough energy to get up."

Staff at the centre first thought it was a gannet until managers did some research and realised it was a frigatebird.

The Department of Conservation and Auckland Museum visited on March 13 to confirm the type of bird.

Whelan said she was "really excited" about having the bird at the centre.

The centre had not released any information earlier because staff were unsure if the bird would survive due to its low weight and weakness, she said.

However, the bird was steadily improving and now weighed 815 grams.

It was more alert and has begun to flex its wings, Whelan said.

But word had managed to get out about the rescue centre's latest arrival, she said.

"We've had a lot of people contacting us about it because they have heard about it so it's really quite exciting news for people who are into birds."

New Zealand Birds Online said lesser frigatebirds were "distinctive" tropical seabirds that only occasionally reached New Zealand.

There had been about 40 sightings of the bird around the country, it said.

Lesser frigatebirds were predominantly black with long narrow wings, the website said.

They ranged in length from 70-80 centimetres and weighed around 1 kilogram.

Whelan said the bird would likely be released on an island in Hauraki Gulf.

Staff would keep an eye on it for a while in case it needed help, she said.