WHEN it rains ants, it pours—at least when birds are around.
Northern wood ants, Formica aquilonia, have a habit of dropping or
“raining” off the branches of trees in their droves. Paul Haemig from UmeÃ¥
University in Sweden has found that they do it most when there are birds around.
When no birds are in sight, up to 12 per cent of ants can join a downpour, he
says. But when birds come foraging, almost 30 per cent take the plunge (
Animal Behaviour, vol 54, p 89).
Haemig says some ants are being swept out of the trees by air currents from
the birds’ wings, but he also claims to have seen ants deliberately jumping: he
saw an ant “run faster for a few centimetres, and then jump off the tree by
springing outward”.
