Locally extinct bird lured back to remote island with audio recording

After rats invaded the island more than 40 years ago, wild birds began to disappear. So a group of scientists took tried a novel approach to get them to return.

Pajaros Uno Island from above using a drone.
After researchers set up the sound systems, the calls of Peruvian diving-petrels could be heard up to 300 metres away. Source: Island Conservation

Decades after a rare creature disappeared from a remote island, researchers have used recordings of its deep mesmerising call to lure it home.

Pajaros Uno Island was home to multiple colonies of nesting seabirds, but then rats invaded and feasted on the chicks. While some more hardy species persevered, the island's rare black and white Peruvian diving-petrels fled and became locally extinct.

“Fishermen who were visiting would say you could see only rats on the island. It was full of rats and you could see rats in daylight which is not usual on islands,” Jose Cabello, from non-profit Island Conservation told Yahoo News on Wednesday.

But less than a year after Carbello and his team declared war on the rodents and restored the 70-hectare Chilean island as a safe space for birds, two Peruvian diving-petrels pairs have returned. And it appears the sound recordings are making them feel safe to nest there once again.

You can listen to the sound that was played below.

If you haven’t seen or heard of Peruvian diving-petrels you’re not alone. While they once flew up and down Chile’s coast in their millions, there are now no more than 100,000. They are listed as near threatened on the IUCN Red List of species facing extinction.

Their return to the island is significant because the species is now locally extinct in many of its former breeding burrows, which were mined for a seabird poo fertiliser called guano.

Related: World’s largest ever animal rediscovered living near tiny islands

Close up of a Peruvian diving-petrels chick.
Peruvian diving-petrels chicks have been located on Pajaros Uno Island once again. Source: Island Conservation

The continued loss of birds may have eventually destabilised the entire surrounding seven island chain – the Coquimbo Coastal Current System which lies 20km west of Chile's coast – because the nutrients from the guano sustain the surrounding reefs.

The predator removal program began in 2020 and two years later Pajaros Uno was declared predator-free. The audio recordings were played on a specialised solar-powered sound system and during the night when the sea was calm the sounds could be heard up to 300 metres away from the island.

“We played a safety call, and it stimulated the curiosity and then the visit of the petrels,” Cabello said.

A Peruvian diving-petrel in the water with its wings up.
Peruvian diving-petrels had not been seen on Pajaros Uno Island since rats invaded. Source: Island Conservation

While the repetitive, almost mammalian sound of Peruvian diving-petrels may be irritating to humans, it's soothing to members of the species. Five-minute recordings of nesting sounds were first played on a five-minute loop back on November 3 and a Peruvian diving-petrel was spotted 13 days later.

But access to the island is restricted and it was only recently that researchers were able to confirm the birds had nested. Photographs they have since collected show there are chicks inside the burrows.

“We found a natural nest. It was absolutely exciting. It looks like the birds have tried to put their nest close to the sound, almost underneath the system to feel like they are in the middle of a colony,” Cabello said.

Island Conservation's next step will be to confirm that the birds are continuing to do well and to continue to keep the island predator-free so more rare birds return. The research is supported by the David and Lucile Packard Foundation and the National Fish and Wildlife Foundation.

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