BirdLife: The Magazine June 2017 - Page 20

THE SEX ISSUE IT PAYS TO DISPLAY Before sex, of course, comes the courting period – and few know how to catch the eye quite like birds. Males have evolved an array of dazzling displays designed to attract females, strengthen pair bonds and prove they’re made of the right stuff to raise their would-be partner’s young Alex Dale 20 BIRDLIFE • JUNE 2017 THE EYES HAVE IT INDIAN PEAFOWL Pavo cristatus Photo Percom/Shutterstock In most bird species, the males are the flamboyant sex, and the females are the ones who do the choosing. This arrangement has come about because the process of producing eggs involves a great amount of energy on the female’s part, so she is extra careful to ensure that these efforts aren’t expended on a male who will produce weak offspring. Females take the business of selecting a mate seriously, scrutinising their calls and their plumage for any JUNE 2017 • BIRDLIFE IN MOST BIRD SPECIES, MALES ARE THE FLAMBOYANT SEX hints that can tell her about his strength, health or vigour – traits, after all, that will be passed on to his young. Thus, to maximise their chances of spreading their genes, in some species the males have developed flashy courtship displays to show off their charms in the best possible light, and woo females away from their rivals. Traits preferred by the female of the species are exaggerated over time. There is no better, or more famous, illustration of the evolutionary cost of this process for the male than of the peacock – encumbered, thanks to many generations of sexual selection, with an impossibly ornamental tail, which it flares in spectacular fashion in its attempt to court a peahen. 21