Jul 12, 2019

Bird Migrations

We think humans travel far, but it seems some birds have us beat and without planes or Uber. Of the nearly 10,000 species of birds, about 19% (1,850 species) are considered to be migratory. The 13-15 inch, 3.5 ounce Arctic Tern takes the prize for the longest migration at an astounding 44,000 miles (71,000 km) annually on average.

By tagging the birds, scientists learned the shortest migration was 36,900 miles (60,000 km) while the longest was 50,700 miles (81,000 km). For perspective, the circumference of the Earth is 24,901 miles (40,075 km).

This migration is completed annually at every life stage. The Arctic Tern can live for 35 years, so a single bird can potentially travel about 1.5 million miles (2.4 million km) in its lifetime.

During its migration, the Arctic Tern completes a round trip from Greenland, traversing the Weddell Sea and flying along the shores of Antarctica. The birds take a break at sea over the North Atlantic Ocean while they fuel up on food. Once this break is completed, the birds head down the coast of northwest Africa, around the Cape Verde Islands, then off the west coast of Africa towards Senegal.

Rather than traveling straight back along the path they came, they instead travel in a twisted ‘S’ shaped pattern through the Atlantic Ocean. Though this route adds many miles to their trip, the birds take advantage of the global wind system and use less energy, thanks to the wind currents.

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