Antarctica is a real bird paradise. The Southern Ocean provides a rich food base and the remote islands provide excellent breeding opportunities. Especially the albatrosses and the different petrel species stand out with their body sizes and their way of life. A representative, the northern giant petrel is special on that occasion again in many respects. Now Australian researchers have reported that this species probably is also surprising in terms of age, because a forty-year-old animal was discovered.
The bird was discovered dead on a New Zealand beach. Since it was banded, the age and also the place of origin of the bird could be determined exactly. Information about the find was then passed on to scientists at the Australian Antarctic Division AAD. From the information it was apparent that the bird originally hailed from Macquarie Island and was now forty years old.
Dates on the bird’s band showed it had been banded as a chick at Mawson Point on Macquarie Island on January 23, 1981. This makes the animal the oldest known representative of its species. For the researchers of the AAD, the discovery of the bird is a real stroke of luck. The data not only provide information about the age of the bird, but also about its preferred locations during its long life. The tape was part of a program to collect such data. “Between 1967 and 1987, more than 3,000 northern giant petrels were banded on Macquarie Island alone,” explains Dr Barbara Wiencke, seabird specialist at the AAD. “With a recovery rate of only 2 percent, lots of birds had to be banded to recover just a small number.” Australia’s banding program was established in 1953 to find out more about the migratory habits of birds and bats on Australian soil. Meanwhile, the birds on subantarctic islands and in Antarctica are no longer banded, as this is stressful for the birds. More reliance is being placed on satellite tracking as this is more detailed and accurate in addition to being easier to attach.
The data that the researchers take from the banding program is very revealing. In terms of age, 40 years is a real record. Normally the time span between banding and recovery is a little more than 8.5 years, experts say. However, this says nothing about the longevity of giant petrels. The data are also very exciting in terms of migratory behaviour. There are more than 2,200 kilometres between Macquarie and where the old bird was found in New Zealand. Northern giant petrels are native to the entire Southern Ocean region and also migrate long distances between breeding and feeding areas. “In a satellite tracking study of northern giant petrels from Macquarie Island, some adult birds travelled more than 2,000 kilometres during the breeding season,” explains Dr Wienecke. The record of one animal is 10’846 kilometres, from Macquarie to Namibia.
This shows that not only albatrosses cover long distances in the course of their lives, but also giant petrels. This fact was also shown in another recently published study. This means that the birds are also at risk from deep-sea fishing, especially longlining. They have a very wide food spectrum and eat krill and fish as well as squid, which are used as bait in longline fisheries. They also eat carcasses and weak and sick young on the beaches of the subantarctic islands. This makes the primitive looking birds not the most beautiful photo subjects, but the most ecologically valuable. It is therefore important that these animals can continue to reach their old age undisturbed.
Dr Michael Wenger, PolarJournal
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