Tuesday, May 17, 2011
Southern Giant Petrel
I had read a few reports about a Southern Giant Petrel seen at Mornington beach in Victoria, it was only a short drive so I went to investigate. Sure enough, there it was. Only a young bird, it seemed more at home on the water than on land. It waddled along the beach and approached within a metre of me before returning to the water and feeding on the remains of a fishermans catch. Some information from the Queensland Department of the Environment:
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.