Satellite tags employed to solve albatross's mysterious decline

British Antarctic Survey (BAS) has satellite tagged 16 juvenile Grey-headed Albatrosses in order to understand what is driving the species' rapid decline.

Grey-headed Albatross is now classified as Endangered due to a catastrophic population drop on South Georgia, its largest breeding stronghold. Since 1977, numbers have more than halved, and over the last decade the decline has accelerated to a worrying 5 per cent a year – far faster than any other albatross species. Colonies that once teemed with nests and chicks are now sparse, with large, bare areas of tussocky grass dominating slopes that were once predominately teeming with birds.

A comparison of the Grey-headed Albatross colony on Bird Island, South Georgia, in 1979 and 2017 (British Antarctic Survey).

The reason for such a startling decline was unknown. By recording sightings of ringed birds, researchers worked out that juvenile survival rates were far lower than normal. When they fledge, juveniles rove the Southern Ocean in search of food for up to seven years, before returning to breed on South Georgia. Exactly where they are going has remained unknown, although scientists do know that it involves different areas to the adults.

The only clue was a handful of reports from Japanese longline fishing vessels, which had been reporting juvenile Grey-headed Albatrosses as bycatch. However, there was some confusion over whether they were being wrongly identified, as they are notoriously hard to distinguish from juveniles of other species. With too many youngsters going missing after fledging and no confirmed knowledge of where they go, scientists decided to fit satellite transmitters to fledglings at their nests on South Georgia, with a hope to solving the long-standing mystery.

Satellite tags were attached to 16 chicks in the nest (Derren Fox).

Of the 16 youngsters fitted with the transmitters, only nine successfully managed to leave the island. One of the side effects of a declining population with more spread-out nests is that it leaves fledgling albatrosses more exposed to predation from giant petrels, which accounted for the deaths of seven of the tagged juveniles before they could take to the air.

Despite this setback, the remaining nine juvenile Grey-headed Albatrosses are now at large in the Southern Ocean, and researchers have become engrossed with monitoring their progress.

"Initial results have shown some of the juveniles headed to the area where they were reported to have been killed by the Japanese fishery, which is the first time we've tracked the species to that area," explained Stephanie Winnard, International Marine Project Officer for the RSPB. This ties in with recent research by the RSPB and BAS, which showed high overlap between Grey-headed Albatrosses from South Georgia and the extensive tuna fisheries of Japan and Chinese Taiwan.

Once this has been confirmed, the Global Seabird Programme can get to work. "We had already been engaging with the fishing agencies of Japan and Chinese Taiwan, as well as directly with some of the fishermen themselves," added Winnard. "Now we can ensure this work is even better targeted to try and ensure that these incredible voyagers can get home safely."

You can follow the progress of the young albatrosses by clicking here.

Grey-headed Albatross is now listed as Endangered, but it is hoped that this year's research will provide a valuable insight into ongoing declines (Steve Copsey).