The Transworld Journeys of an Amazing Bird 

New Data Helps Scientists Track Arctic Terns from Greenland to Antartica

by Nancy Garduño, age 13

The Arctic tern is a bird with a reputation for being well traveled. It has the ability to migrate to the far Southern Ocean from its Arctic breeding grounds. Researchers estimate that the round-trip distance could be as much as 25,000 miles.
   
Scientists interested in studying the journey of the Arctic tern face many obstacles. 
   
Devices, such as tracking tags, are usually used to locate Arctic animals. Large birds like albatrosses can be tracked by using these tags. However, smaller animals like Arctic terns, which weigh less than four ounces, are too small to carry these tags.
   
Carsten Egevang and his colleagues at the Greenland Institute of Natural Resources, have found a solution to this problem. By creating a tiny data logger weighing just one-twentieth of an ounce, scientists can now measure the light intensity, timing of sunrise and sunset, and length of twilight to calculate latitude and longitude. This tells them the bird’s whereabouts.
   
In a recent experiment conducted by the National Academy of Sciences 11 terns took a journey fitted with the devices. Beginning in Greenland or Iceland during August, terns took two routes southward. Some outlined the African coast and others crossed from West Africa to Brazil to follow the South American coast. They stopped for about three weeks in a plentiful feeding zone in the mid-Atlantic east of Newfoundland.
   
Once they reached the Southern Ocean, the terns spent four months flying mainly east and west, through food-rich areas. Arriving back home in May and June, the terns had traveled on average 44,000 miles. One tern in particular totaled an astonishing 50,700 miles—the longest animal migration ever recorded electronically.

Source: [The New York Times]


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