KEY POINTS:
The wandering albatross does just what its name suggests: wandering at random in its long search for food in the southern oceans of the world, a study of the bird has found.
Experts used to think that there was a hidden method to the apparent madness of the
albatross's long-distance flights, which can take the bird from one corner of the world to another, and back again, in search of a meal. However, scientists have found that the wandering albatross has no apparent strategy when it comes to where it decides to land on the ocean and forage for squid and fish.
More than a decade ago, scientists were astounded to find that when they tracked the movements of the wandering albatross, the bird seemed to carry out a search pattern that followed a Levy flight, a pattern named after the French mathematician Paul Pierre Levy.
A Levy flight occurs when a search is conducted in a semi-orderly manner, with clusters of short searches over a relatively small area interweaved between long-distance flights from one region to another. Mathematicians showed this was an optimal strategy for foraging for sparse food.
But scientists have collected fresh data on the feeding habits and movements of wandering albatrosses living on the sub-Antarctic island of South Georgia. They used logging instruments that monitor when they land on water and how long they stay there between flights.
The results, published in the journal Nature, reveal that the birds do not follow a Levy flight pattern. When the scientists reanalysed the earlier albatross data, they found that it too did not conform to the mathematical pattern, as previously reported. They also analysed earlier studies of foraging patterns of bumblebees and deer, which were also thought to forage using the Levy flight pattern, and discovered that they too failed to conform to the expected pattern of movements.
"It now seems that the albatrosses come across food at simple random intervals. Our work also questions whether other animals thought to exhibit Levy flights do all forage in the same way," said Andrew Edwards, who carried out the work at the British Antarctic Survey, located in Cambridge. "The idea of albatrosses following a Levy flight pattern was quite appealing. They can travel up to 10,000 kilometres on one foraging trip. But at the moment these results question that they adopt this kind of foraging strategy."
- Independent
