The communal nests are guarded by about a dozen Terns, who are either feeling unwell or haven’t found a mate. These guards keep away any predators by attacking en masse, putting to flight any animal who wanted to eat the eggs or young chicks.

Central American Terns always fly back to the same areas of Mexico and Columbia on each migration, so the female knows her mate will be back in around seven weeks, by which time both she and her fledglings will be strong enough to fly back on the next migration.

This is an extract from the book Animals Evolution Avoided