It’s an attractive piece of real estate – coastal living in a safe neighbourhood with waterfront views, 55km south-west of Melbourne. The floating island, installed at the Avalon coastal reserve on the western side of Port Phillip Bay, features sand and shell grit floorings, and twigs and branches for cozy nooks.

It has been specially designed for Australian fairy terns by BirdLife’s waterbird program manager, Chris Purnell, who has deployed some unusual tactics to charm them.

He says fairy terns were already foraging in the shallow waters of the reserve, located on the site of disused saltworks, and in recent years the birds have even tried to nest on the disused levees. But when water levels dropped, foxes got in, rendering the breeding attempt “a complete failure”.

“What would have been a significant event – 18 nesting birds in Port Phillip Bay, something that hasn’t happened for over a decade – was sabotaged. So we thought we’d give them a floating habitat.”

These small seabirds – just shy of a ruler’s length – are listed as vulnerable under Australia’s environment laws. There are up to 7,500 spread across the southern states. Ornithologist Dr Claire Greenwell – whom Purnell calls “the fairy godmother of fairy terns” – says the “lion’s share” of the birds are in Western Australia.

The floating nest site in Port Phillip Bay designed to give fairy terns a home safe from people and predators. Photograph: Chris Purnell/Birdlife Australia

Fairy terns are faring less well in the east, mainly due to higher populations of people along the coast.

As a beach-nesting bird, fairy terns often lay their eggs on wide sandy beaches next to clear blue water – exactly the sort of places people enjoy for recreation, Greenwell says. The overlap puts the birds and their offspring at risk from people, cars, foxes and other predators, as well as weather events like storm surges.

They lay their eggs directly on to the ground, she says, and the eggs take 21 days to hatch.

In Victoria, there are only about 150 birds left, Purnell says, a situation made worse by the few reliable nesting sites. The floating nest site at Avalon is intended as a safe haven.

But attracting the birds to the purpose-built pontoon requires an element of subterfuge. Fairy terns usually rely on the presence of other fairy terns to see if a site is any good.

“If they’re flying over, they see one of their buddies or a pair of buddies already sitting there, they’re likely to jump on it,” Purnell says.

Using cadmium yellow for the legs and bill, surf mist for their backs and black for their hoods, Purnell has painted a set of 3D-printed fairy tern decoys, randomly placing them in pairs to create the illusion of birds already using the site.

The fairy tern models have even fooled other birds. Photograph: Chris Purnell/Birdlife Australia

Do birds know the models are fake?

“I think they’re pretty convinced,” he says. “I had cameras on them – you could see the other birds’ reactions to them.

“The ravens would attack them. They got right up in their face, thought that they were real and were looking around for chicks. We had a heron come in and knock one over.”

To add to the conceit, Purnell broadcasts fairy tern courtship calls from the onsite cameras – another ruse designed to attract passing birds.

It might seem like an unusual strategy, but Greenwell says the approach – which scientists call social facilitation – has been used for seabird restoration all around the world, with many examples where it has been hugely successful.

“It’s used to encourage birds back to sites where they have formerly nested, or it can be used on artificial sites that we’ve created, as a method to encourage them to a potentially safe area.”

The floating nest site, supported by the Corangamite Catchment Management Authority and the Victorian government, is just one way to help the birds. Beachgoers can make simple changes to protect the eggs and chicks during spring and summer – like not driving on the beach, keeping dogs on a lead and staying away from nesting areas.

“Fairy terns, as a beach-nesting coastal seabird, cannot thrive unless we have the community on board because of where they nest,” Greenwell says.