Where does the critically endangered Herald petrel go when it leaves Queensland?
On the northern edge of the Great Barrier Reef, approximately 620km northwest of Cairns, is a small, remote coral cay called Raine Island. This remote location is the only known Australian breeding site of the critically endangered herald petrel (Pterodroma heraldica).
In partnership with the island’s Traditional Owners—the Wuthathi People from Cape York and the Meriam Nation (Ugar, Mer, and Erub) People from the eastern Torres Strait—the Raine Island Recovery Project team visits the coral cay at least three times a year. During an early field trip, while scientists were undertaking other work, they spotted a herald petrel flying straight towards them. The most distinguishing feature of these seabirds is their unique flight patterns, making them stand out from other birds on the island.
The herald petrel spends most of its life arching and gliding over oceans, returning to land only to breed. They have short, sturdy bills, suitable for picking soft prey from the water surface or biting scientists when they catch them on land. Senior conservation officer Dr David Stewart said most of the team, which includes Traditional Owners, don’t mind.
“It’s often safer for us to get bitten than to cause them harm by wearing heavy protective gloves,” David said.
He has studied petrels for almost half a century and herald petrels since they were sighted on the island about a decade ago. David explained we still have much to learn about the species.
“We are limited by what we can learn about the herald petrel because we only observe them for a few short days in the winter when they visit Raine Island to breed. When we return in the summer, they have gone. We have seen some behaviours, like their courtship flights, which consist of high-speed synchronised dives and loops over the island, but we have many unanswered questions.”
Each year, the team surveys and monitors the bird’s ecology and breeding success. In the first survey, they caught and banded 24 herald petrels. They now estimate 40–50 herald petrels breed on Raine Island.
In June 2017, they found an adult herald petrel caring for a single egg. Returning two months later, they were thrilled to discover a healthy-looking chick, confirming this seabird breeds in Australia.
In 2018, the team caught 18 petrels, attaching small geolocators supplied by the Zoological Society of London. Twelve months on, they caught 15 of the 18 tracked petrels again at Raine Island and removed their geolocators. Two years later, they found another two tracked birds. By 2023, 17 of the 18 tracked birds had returned. Unfortunately, the last one has vanished.
The trackers provided general information about the birds’ movements for the first time in Australia. They showed that after breeding, the petrels stayed within the Pacific Ocean, dispersing east towards the Solomon Islands before changing directions to an area north of New Guinea before returning to Raine Island. The birds cover 3,500–4,000km each way. The team plans to use more sophisticated trackers to study the birds’ movements in real time.
“We need to gather baseline data now that we can use in future years to study how climate change impacts their behaviour,” David said. “For example, a change in sea temperature of a couple of degrees may affect their ability to feed, and sea-level rises may impact where they lay their eggs on the sand.”
With permission and in collaboration with the Wuthathi and Meriam Nation Peoples, the team are also assisting David to collect blood samples for genetic testing by CSIRO and the University of Tasmania.
“Genetic testing will establish if they are a distinct species and how related they are to other herald petrel populations,” David said.
“We have observed dark-plumaged petrels on Raine Island, which may be a different species. Recently, we have also seen a bird from another species bonded with a herald petrel. We don’t know if they had chicks, but if so, that throws new genes into the population.”
About Raine Island
Raine Island is a protected national park for scientific purposes and is inaccessible to the public. Raine Island supports the world’s largest remaining green turtle nesting population and hosts up to 84 bird species, with 16 of these known to breed on the island. See Raine Island Recovery Project.