Life’s Good at the Mega-Roost
It’s one of the most spectacular mass migrations on Earth, but one that has largely remained hidden from human eyes. Each year, millions of straw-colored fruit bats fly to Zambia’s Kasanka region in October, drawn by the area’s bounty of fruits like figs, loquat, and mango. Giant masses of bats roost in nearby trees, clinging to branches that sag or break under the collective tons of weight.
As evening falls, 150,000 bats per minute will leave the roost to forage, flying as far as 37 miles and in the process pollinating flowers and dispersing millions of seeds from ecologically and economically important trees. Over the course of their stay, the bats will consume twice their collective body weight in food and devour the equivalent of several billion bananas. While predators routinely attack the mega-roost, the sheer size of the roost deters some birds of prey; those hunters that do succeed in picking off a few bats have a negligible impact on the group as a whole.
Ten weeks into this mega-roost, just as mysteriously as the bats arrived, they depart—in some cases flying more than a thousand miles to the Congo rainforest.