LONDON - A bird called sooty shearwater is now the undisputed holder of the record of having the longest migration. These birds also known as the Muttonbird and Titi replace Arctic terns as having the longest migration period.
The bird traverses Pacific Ocean in a figure-eight pattern annually and records 74,000km in the process. In contrast the Arctic tern travels only about 35,400km between the polar icecaps. Scientists wanted to test the distance traveled by the sooty shearwater (Puffinus griseus) and hence fitted 33 birds with electronic tags. These tags were able to record position, air temperature as well as the depth to which the birds dived while feeding.
One year after the tags were fitted, scientists managed to recover 20 of which 19 provided the full information required. "These extraordinary migration routes represent the longest recorded of any animal tracked to date," scientists report in the Proceedings of the National Academy of Sciences.
The records showed that the birds traveled about 1094km a day. Sooty shearwater typically has breeding burrows in New Zealand. From here the birds went to the northern hemisphere and reached Japan, Alaska or California for feeding. "The only other bird species known that could rival the migrations of the sooty shearwater would be the arctic tern. But we don't know if they do that in a single season, because nobody's ever tracked them," said Scott Shaffer, of the University of California, who was a part of the international research team, which conducted this study.
To catch fish, the birds dived 14m, but could dive up to 68m when required. "When they cross the equator, they're traveling fast and not stopping much to feed," Dr Shaffer said. "They feed near Antarctica during the austral summer, then zip north to feed in one of three areas of the north Pacific."
Sooty shearwaters are abundant in Atlantic Ocean with their numbers approaching 20 million. But in recent times this number is falling rapidly.
