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Girl power at Mangawhai Beach School is behind a move to save New Zealand's rarest and most endangered bird, the fairy tern.

Jamie Davies, Alana Torrie, Tahlia Howard and Holly Brooks have designed T-shirts and lanyards, and organised a design-a-sign competition as part of a school project dubbed "Tern Around", looking to raise awareness of the bird.

The girls, who are all 12 years old and in year eight, are involved in the school's Community Problem Solving team, which sees gifted students identify and aim to solve an issue within their community, Tahlia said.

"We found out about the tern and that it's breeding right here in Mangawhai, so we decided to do that. We mainly want to raise public awareness because everyone thinks that the kiwi or takahe is the most rare. But it's the tern," she said.

Tern Around has been running for more than a year, researching the fairy tern and talking to community groups, and is set to approach organisations to help fund its projects.

Other schemes the girls have come up with include a story book for children and a programme called Sponsor a Pair, which gives sponsorship money to local volunteer group About Tern.

Coach Rob Posthumus says the group's "kid power" and the girls' passion to try to change the environment in some way is what has made the project effective.

"As a result of their agricultural display at school, lots of the community are volunteers now, after seeing what the girls have done," Mrs Posthumus said.

Last year, the group attended Future Problem Solving New Zealand, where they won second place.

The New Zealand fairy tern is unique with its own DNA and is the most critically endangered bird in the country, with just under 50 terns nationwide.

Predators such as rats, hedgehogs, dogs, ferrets and people riding their motorbikes over its nests in sand dunes are what is killing the terns' eggs, Alana said.

Jamie added: "A baby tern is the size of a bumble bee."

Five winning designs from fellow students have been chosen and the group is now looking for sponsors, to fund the signs to be made and then erected around the Mangawhai sand dunes.

Tahlia said: "We don't want it to get extinct and we want people to be more considerate."