Nature notes: trouble for swifts

The rain is making life difficult for swifts. In sunny weather they go torpedoing through the sky on their curved-back wings, picking up flying insects and small, drifting spiders — the so-called aerial plankton that gets carried up by warm air currents. When it is raining, there is little to be had up there. Their solution is to fly, often a long way, to the edge of the rain, and especially to the rear of a depression where warmth is lifting their food back into the sky again. Now some swifts have eggs in their nests under the roofs, and these are in danger of getting cold if the incubating bird is hungry and has to fly off for a long time. Also, later in June, the nestlings that have hatched successfully will be at risk of starving if it rains and their parents find it hard to collect food. However, nestling swifts have the ability — unusual for infant birds — to draw on fat reserves, and can go without food for several days without coming to any harm.