Wandering albatross - the largest flying bird on earth. Its 3,5 meters wingspan gives the spectators unforgettable memories watching this majesty glide effortless over the water. Unfortunately, at present highly endangered due to large numbers being killed each year due to the longline fishing industry. Photo: Eirik Grønningsæter
By observing birds along 15 degrees east from Cape Town to the Antarctica, there will be added an extra ecological parameter to this research effort, which is otherwise mainly concerned about different aspect of the Antarctic krill in the Southern Ocean. The method used, is a modified version of the distance sampling method used for open seabird counts in the Barents Sea area in the north. The methods are modified because the species in the southern hemisphere is different from the ones found in the northern hemisphere, both in feeding techniques, general behaviour and ecology.
As most of the earlier research on birds in the Southern Ocean either is concentrated on open sea very close to land, or at the breeding sites themselves, this study is one of very few that explores the bird life far from such areas. Therefore, it was with great excitement I stepped onboard the boat in Cape Town’s harbour area, and knew that in the 40 days to come I will be surrounded by interesting birds, and hopefully produce new insight in the big puzzle of the seabird ecology in the Southern Ocean . Since the literature from this type of survey in the area is very limited, I didn’t really know what to expect. I hoped for a lot, but so far I have got more than that!
The handsome and smart looking light-mantled albatross is a true cold water species restricted to Antarctic waters, and is only encountered by the most fortunate. Photo: Eirik Grønningsæter
Immediate results show itself in the differences in the distribution of several species compared to what is believed in available literature. It is extremely interesting to see how the avifauna (bird fauna) changes, virtually from latitude to latitude moving south. As we rides the waves towards colder waters, some species fly away, always replaced by new ones that didn’t exist further north. The only species to occur every day on the cruise is the white-chinned petrel (Procellaria aequinoctialis). The largest concentration of birds was actually encountered just south of Cape Town, as we passed the continental shelf, where the bottom drops off, in rich and traditional fishing areas for the locales.
The ultimate dream
Just after this, we also encountered fairly good numbers of Leach’s storm petrel (Oceanodroma leucorhoa) a scarce species off the continental shelf of South Africa coming from Europe to spend the winter down south. The avifauna stayed much the same in the next two days, with shy-(Thalassarche cauta) and black-browed albatrosses (T. melanophrys) being quite numerous. For a birdwatcher from the Northern Hemisphere interested in seabirds, albatrosses have always been some kind of the ultimate dream to experience. Their gracefulness and the aura of tranquillity these great seafarers express are truly amazing. No human being – birder or not – will come out of an albatross encounter untouched.
There is, however, a sad side to the story of seabirds in the Southern Ocean. Albatrosses, and other seabirds, has for some years (and still are) being killed in the number of thousands each year because they get hooked when trying to grab the bait on the fishing hooks from extensive longlining activities aimed at high prized tuna species. This happens when the fishing vessels are putting their baited longlines, up to 130 km long, into the sea. It is internationally agreed upon that they need to change methods, so the bait is placed well below the surface (through tubes for instance) before the bait get out into the open sea. The problem is that about 1/3 of the world’s fishing fleet is illegal in international waters, and these do not obey neither new nor old regulations.
Between 105 900 and 257 000 seabirds were estimated killed by longline fishing from 1996-2000. This figure includes some 21 900-68 300 albatrosses and illegally fishing vessels are thought to kill 10% (per boat) more than licensed ones. Several species only breed every second year, and then only one chick is produced. Snowy albatross (Diomedea exulans), which belong to the wandering albatross group – does not mature and is thus unable to reproduce before they reach about 10 years of age. This means that they are extremely vulnerable to decrease in adult survival.
As a result of this, they belong to one the most threatened group of birds on this planet. One the most threatened seabirds, the spectacled petrel (Procellaria conspillata) we already had the fortune of meeting 5 times during this survey. The species only breeds on Inaccessible island in the Southern Atlantic and in the year 2000 the population estimate was 10 000 individuals. However, the species is in fast decline as it is believed that about 5% of the population is killed by longliners off the coast of Brazil each year! This slaughtering of seabirds by longline fishing vessels has become a very (if not crucial) part of any Southern Ocean seabird species’ life and ecology and it is important that everyone conducting any work in these regions is aware of this problem.
Abundant blue petrel
Far south in our study area, the blue petrel (Halobaena caerulea) became abundant and daily numbers of 500-1000 individuals were logged. We also encountered true cold water species like the light-mantled albatross (Phoebetria palpebrata), which with its smiling and smart looks is every birdwatchers dream to see. Especially for a Norwegian, it was also very nice to see the Antarctic petrel (Thalassoica antarctica) where many of the species’ colonies are situated as far as 300-400 km inland on the Antarctic continent. One of these colonies is situated just next to the Nowegian research station “Troll” on the nunatak “Svarthammaren”. Breeding this far from the sea means that the parent needs to fly at least 800 km roundtrip just to feed their single chick!Blue petrel is the most common species during our cruise. We have only found it in cold waters, but in the Austral winter the species migrate northwards reaching the landmasses of South Africa and South America. Photo: Eirik Grønningsæter
Apart from looking at distribution of species, it is also an important objective of this cruise to link the echosounder and sonar data as well as oceanographical data from the boat with the bird counts to look at spatial distribution in correlation to zooplankton and habitats. However, it is yet too early to say anything about these results.
Stuart Murray, an independent Scottish birder, is also on board the ship. His objective is to investigate the different moult stages and look at plumage variation in the world’s largest flying seabirds – the wandering albatross group. These albatrosses can reach a wingspan of 3,5 meters and it’s gracefulness is extremely impressive to watch even for the ones on board not normally remotely interested in birds!
Written byEirik Grønningsæter
This birdwatcher for more than 20 years has a cand.scient degree in Zoologi from the University of Oslo. During the summers Erik usually works as field assistant for different scientific projects, mostly related to birds. On this cruise he represent the Norwegian Polar Institute. During the winter season he works as a freelance nature photographer, and is running the website www.WildNature.no