WHEN it rains ants, it pours鈥攁t least when birds are around.
Northern wood ants, Formica aquilonia, have a habit of dropping or
鈥渞aining鈥� off the branches of trees in their droves. Paul Haemig from Ume氓
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鈥� wings, but he also claims to have seen ants deliberately jumping: he
saw an ant 鈥渞un faster for a few centimetres, and then jump off the tree by
springing outward鈥�.
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