Why bats are nocturnal
Many of us believe that bats hunt at night to avoid predators. But, scientist John Speakman of the University of Aberdeen says his observation of bats in the 24-hour daylight of the Arctic summer casts doubts on that theory. Most probably, he says, bats fly at night to avoid competition with insectivorous birds. Flying consumes so much energy that each female bat is only able to produce a single off-spring a year. An insectivore, on the other hand, might produce five young ones every six weeks. If bats flew during the day, when most insects are active, they could eat enough to overcome this problem