There's an interesting article on the BBC News site this week about the mystery of the Amazonian Manatee's migration habits.

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 may be at greater risk than 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.