Scientists on sub-Antarctic Macquarie Island have used satellite tags to track the foraging behaviour of a threatened sea-bird, the grey petrel, for the first time. The grey petrel weighs one kilogram and is a burrowing seabird which breeds on Macquarie Island, half way between Australia and Antarctica.

The grey petrel (Procellaria cinerea), also called grey shearwater, occurs in the open seas of the Southern Hemisphere, mainly between 49°S and 32°S. The biggest colonies are at the Antipodes Island, with an estimate of 53,000 pairs, and Gough Island with 10,000 pairs. Here a chick is identified with a small silver leg band. (Photo: Marcus Salton)
The grey petrel (Procellaria cinerea), also called grey shearwater, occurs in the open seas of the Southern Hemisphere, mainly between 49°S and 32°S. The biggest colonies are at the Antipodes Island, with an estimate of 53,000 pairs, and Gough Island with 10,000 pairs. Here a chick is identified with a small silver leg band. (Photo: Marcus Salton)

Parks Wildlife Ranger, Marcus Salton, said researchers have been studying the birds on the Macquarie Island for the past 16 years but until now knew nothing about their at–sea foraging behaviour and habitat use. “Over winter for the first time we attached a small satellite transmitter to ten adult grey petrels to track their movements over more than 100 days,” Mr Salton said.

Small satellite transmitters were attached to the back of 10 grey petrels to track their movement over more than 100 days. The results showed that some birds flew as far as 3000 km. (Photo: Marcus Salton)
Small satellite transmitters were attached to the back of 10 grey petrels to track their movement over more than 100 days. The results showed that some birds flew as far as 3000 km. (Photo: Marcus Salton)

“The results were astounding, showing the birds foraged over a very broad area. Some flew as far as 3000 kilometres east of Macquarie Island past New Zealand, while other birds foraged several thousand kilometres northwest near to Australia”, Mr Salton said. “The tags also show the birds regularly return to their burrows on the Island during the breeding season.”

The grey petrel is currently listed as a threatened species due to impacts on the birds on land and at sea. Introduced predators such as cats, brown and black rats are contributing to the decline, as well as longline fishing, which is a major problem. One estimate says 45,000 birds were caught by fisheries in the last 20 years. Other predators are the weka, a large, brown flightless bird native to New Zealand and the house mouse.

An adult grey petrel sits with its chick in the burrow. Grey petrels build their burrow on steep well-drained terrain. By late March or early April, they lay their one egg, which both birds incubate. After hatching, the chick is cared for by both birds until it fledges between late September and early December. (Photo: Richard Dakin)
An adult grey petrel sits with its chick in the burrow. Grey petrels build their burrow on steep well-drained terrain. By late March or early April, they lay their one egg, which both birds incubate. After hatching, the chick is cared for by both birds until it fledges between late September and early December. (Photo: Richard Dakin)

“This at-sea foraging data will help identify key feeding grounds for grey petrels during their breeding season. With this information, we can better manage fisheries interactions with the birds and explore the potential impacts of changing ocean conditions on the health of the grey petrel population.”

The research is a joint initiative of the Tasmanian Department of Primary Industries, Parks, Water and Environment and the Marine Conservation Program Albatross and Petrel program.

An adult grey petrel coming in to land. On their foraging trips they will dive from heights up to 10 m for food such as squid, fish and crustaceans. (Photo: Marcus Salton)
An adult grey petrel coming in to land. On their foraging trips they will dive from heights up to 10 m for food such as squid, fish and crustaceans. (Photo: Marcus Salton)

Source: Australian Antarctic Division