Southern giant-petrel
Common name: Southern giant-petrel
Scientific name: Macronectes giganteus
Family: Procellariidae
Conservation status: The southern giant-petrel is 'Endangered' in Queensland (Nature Conservation Act 1992) and 'Endangered' nationally (Environment Protection and Biodiversity Conservation Act 1999). It is ranked as a medium priority under the Department of Environment and Resource Management Back on Track species prioritisation framework
Description
Southern giant-petrels have wing spans between 150-210cm and are as large as a small albatross. Unlike albatrosses, southern giant-petrels have large boulbous horn coloured bills and tipped with pale green with a nostril tube lying on top of their bill. Its feet are fleshy-grey. Adult southern giant-petrels are either sooty brown in colour with off white mottling on the head and neck (dark morph) or white with scattered black feathers (white morph). The immature dark morph is sooty brown and gradually become white around the face, followed by head then finally neck with age. Immature white morphs are similar to the adults.
Habitat and distribution
Southern giant-petrels range widely throughout the southern oceans. In summer they occur predominantly below 60°S in sub-Antarctic to Antarctic waters. At this time, they can be found in Australian waters on and around Heard and Macquarie Islands. Some adults are mainly sedentary, remaining close to their breeding islands throughout the year. Nonetheless, their numbers diminish at all sites over winter - the Antarctic colonies are completely abandoned. Throughout the colder months, immature individuals and most adults disperse widely. The dispersal is circumpolar, extending north from 50°S to the Tropic of Capricorn and sometimes beyond. Thus they are common off South America, South Africa, Australia and New Zealand.
In the past, the waters off south-east Australia were particularly important wintering grounds. However in the last 10 to 15 years the number of southern giant-petrels recorded on the east coast of Australia has been in decline. Most (84 percent) southern giant-petrels sighted off south-east Australia are immature birds
Behaviour and life history
Southern giant-petrels nest annually in small colonies amongst open vegetation, with about 30 percent of the potential breeding population not attempting to breed each year. When successful, they raise a single chick. They feed on cephalopods (e.g. squid, octopus, cuttlefish) and euphausiids (krill), attend fishing boats, scavenge on land, and prey on other birds on land or at sea.
Threatening processes
Longline fishing vessels operate throughout the range of the southern giant-petrel. Giant-petrels regularly follow boats eating discarded bycatch.
When attempting to take bait from lines, giant-petrels are frequently caught and drowned on the baited hooks, with significant numbers being killed around breeding islands.
On Macquarie Island, breeding success and/or nest-site selection have probably been adversely affected by predation by rats, cats and an elevated number of Subantarctic skuas Catharacta lonnbergi, although the threat from the latter two has been substantially reduced.. Although not showing much fear away from the breeding grounds, they are sensitive to human disturbance and will desert their nests if disturbed.
Ingestion of plastics and hooks, and their regurgitation to chicks, entanglement in marine debris, human disturbance and accumulation of chemical contaminants may also pose risks to this species. Decreases and extirpations recorded throughout the breeding range indicate present mortality rates cannot be sustained.
Recovery actions
The recovery plan recommends:
- A Threat Abatement Plan (TAP) to minimise fishing bycatch has been prepared and effective mitigation techniques have been developed and are being improved.
- Bycatch rates in the Australian Fishing Zone and the success of mitigation measures have to be monitored and the results quickly analysed .
- Measures known to be effective in mitigating seabird bycatch within the Australian Fishing Zone are promoted in programs directed towards fishing operators.
- Tourists on breeding islands have to be managed to prevent disturbance.
- Continued monitoring of breeding population size and success will determine any population fluctuations.
Further information
Environment Australia. 2001. Recovery Plan for Albatrosses and Giant-petrels. Environment Australia, Canberra.
Last updated 23 March 2011