For the first time, automated cameras are being used on a remote island off the Australian Antarctic Territory (AAT) to record the breeding success and population size of southern giant petrels and the duration of their breeding season.
Southern giant petrels (Macronectes giganteus) inhabit at least three sites in the AAT: Hawker Island, near Davis; Frazier Island, near Casey; and Giganteus Island, near Mawson. Since the 1950s sporadic attempts have been made to record the number of breeding pairs, and the numbers of eggs and chicks on the islands. However, the major focus of earlier visits was to band chicks to determine their distribution once fledged. As a result, the data collected have been inconsistent within and between sites, due to different survey methods and the difficulty of accessing the colonies regularly and at the same time each year. Surveys also have the potential to disturb the birds, causing some to abandon their nests.
To solve these problems, the Australian Antarctic Division is trialling the use of digital cameras to spy on the Hawker Island colony. Hawker Island was recently declared an Antarctic Specially Protected Area to help protect the southern giant petrel (Australian Antarctic Magazine 11: 33, 2006). The species is also protected under the Agreement on the Conservation of Albatrosses and Petrels (ACAP) and Australia’s Environmental Protection and Biodiversity Conservation (EPBC) Act.
Australia has an obligation through ACAP and the EPBC Act’s national Recovery Plan, to monitor southern giant petrel populations and assess population trends. As it is difficult and expensive to get to the breeding islands each year, our hope is that the cameras will offer a cheap and effective way of obtaining accurate and consistent baseline information that will help us better understand population levels and trends for the breeding colonies in the AAT.
The digital cameras, which have been used successfully to monitor Adélie penguins in Antarctica, have been mounted on tripods at each end of the colony and programmed to take a series of photos of the nest sites each day for about six months. The cameras were set up this spring before the birds returned from their oceanic feeding grounds, and will be removed by the Davis wintering party next April, when the birds have left and the sea ice allows easy access to the island. Images from each camera will be downloaded at Davis station and forwarded to the seabird team in Hobart.
Because the Hawker Island colony is small, two cameras should be able to observe the entire colony. We hope that after three to five years of observations it will be possible to define a breeding chronology and population trend. If the 2008–09 trial on Hawker Island is successful, the intention is to progressively establish other cameras on Frazier and Giganteus Islands.
Protecting Southern Giant Petrels
Southern giant petrels breed on the Antarctic continent and subantarctic islands, including Heard Island, Macquarie Island, South Georgia, Marion Island, and Îles Crozet. The largest colonies on the Antarctic continent are found on the Antarctic Peninsula. The birds nest in ice-free coastal areas, rocky bluffs, open flats, edges of plateaux or offshore rocks. Outside the breeding season they can migrate and disperse great distances over the Southern Ocean.
A recent review of southern giant petrel numbers conducted by the Scientific Committee on Antarctic Research estimated a global population of around 54 000 pairs. While there are uncertainties with much of the population data, Parties at the 2008 Antarctic Treaty Consultative Meeting agreed the southern giant petrel population south of 60ºS did not warrant special protection under the Environmental Protocol to the Antarctic Treaty. The small colonies of birds in the Australian Antarctic Territory, however, remain protected by Australian legislation and international agreements.
IAN HAY
Senior Policy Officer, AAD