The mystery of why Amazonian manatees migrate has been solved.

On the run, the gentle manatee migrates away from harm. (Doug Perrine NPL)

Only in recent years did scientists find that the secretive aquatic mammal migrates from shallow to deep water.

Now researchers can reveal that the manatees make this perilous journey to avoid being exposed to attack by predators during the low water season.

That means the species maybe at greater risk than previously thought, say scientists, as migration and low water levels make them vulnerable to hunters.

The international team of researchers from Brazil and the UK publish their findings in the Journal of Zoology.

Great escape

The elusive Amazonian manatee (Trichechus inunguis) is a large plant-eating mammal that lives in freshwater.

Due to its peculiar shape it has been described as a cross between a seal and a hippo.

The species is only found in the Amazon River basin from the river mouth to the upper reaches of tributaries of Brazil, Colombia, Ecuador, Guyana, and Peru.

Every year they are probably migrating through narrow channels where they are exposed to hunters

Dr Eduardo Moraes Arraut
National Institute for Space Research, Sao Paulo, Brazil

The researchers studied manatees that live within the Mamiraua and Amana Sustainable Development Reserves in the north west of Brazil.

To obtain their results, the researchers asked local inhabitants about the animals' movements, studied the shapes and depths of the local rivers and lakes and then used radio tracking tags to follow the movements of 10 manatees.

During the high water season, between mid May and the end of June, manatees live in quiet lakes called varzeas that form within river flood plains, the scientists found.

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