ATTENTION lady nightingales: if you want a big, strong mate, go for the boy who sings his heart out.
Male nightingales sing at night during the mating season, but no one knew if the fittest birds sang the most. Robert Thomas, a behavioural biologist from the University of Bristol, measured the singing time and weight of eight male nightingales over the course of a month. Sure enough, the birds that were heaviest at dusk sang the most and lost the most weight overnight from their efforts (Animal Behaviour, vol 63, p 959). A long song meant the bird was strong enough and clever enough to find food during the day to feed his habit 鈥� and brave enough to risk revealing himself to predators.