On the night watch

As the diurnal delights of the animal kingdom slip into a deep slumber, John Lewis-Stempel explores the velvety black shadows where the wild things are

- John Lewis-Stempel

WHEN the black velvet curtain drops, the farmyard, the meadow, the hill, the river remain the same theatrical stage. But the cast changes at night. Where swallows lacily wheeled around the cowfield in the sunshine comes the nightjar, hawking by hard angles in moonlight. Where butterflies fluttered in the afternoon garden, at midnight the pale ghosts of moths flicker on the honey-suckled arbour. In place of bees on the lane's verge, glow-worms. Instead of the thrush chanting in the orchard, the nightingale serenading. At night, the desolate fen is no longer the hunting ground of the marsh harrier, but of the short-eared owl.

Almost 70% of the world's animals are nocturnal for good reasons. Animals that feed by night exploit sources of food that are also taken by day animals, but without coming into direct competition with them. Also, daylight desiccates and is thus anathema to moist-skinned molluscs and amphibians. Above all, at night, it is easier to evade detection by predators. Darkness is concealment, refuge, sanctuary. It is at night that great mass migrations of British Nature occur, the sweet coming of swallows, the dispersal of moles through the clover-perfumed grass, the eel migrations down the black, slithery river.