Researchers find that white-headed vultures have a surprisingly predatory foraging technique, and could explain why they're less prone to flying into man-made objects like wind turbines. Matthew Stock reports.
Vultures are famous scavengers - feeding off the carcasses of other animals. They're vital to the ecosystem and human health, helping stem the spread of disease by eating dead animals that would otherwise rot. Naturalists believe their eyesight evolved to help them scan the ground for carrion, while avoiding the sun's rays hitting the retina. But this has led to a troubling phenomenon: vultures are prone to hitting objects like pylons and wind turbines. SOUNDBITE (English) DR. STEVE PORTUGAL, SENIOR LECTURER AT ROYAL HOLLOWAY UNIVERSITY OF LONDON, SAYING: "They're not looking where they're going; their whole visual set-up is designed to be looking down. And it's this that makes them so prone to flying into man-made objects ahead of them." But one species - the white-headed vulture seen here - doesn't seem as liable to collision. Along with field observations, researchers examined the binocularity of vulture species. Essentially, they gave them an eye test SOUNDBITE (English) GRAHAM MARTIN, EMERITUS PROFESSOR AT UNIVERSITY OF BIRMINGHAM, SAYING: "We simply examine the eye with an opthalmoscope... we're moving around the bird and working out where we can and cannot see into the eye, whether we can see into both eyes at the same time and that sort of thing." Research published in IBIS, the journal of avian science, found that white-headed vultures are more hunter than scavenger. SOUNDBITE (English) DR. STEVE PORTUGAL, SENIOR LECTURER AT ROYAL HOLLOWAY UNIVERSITY OF LONDON, SAYING: "What we found was that the white-headed vultures actually have a visual system, a visual set-up, that's more similar to active hunting hawks and eagles and much less like their close relatives.... White-headed vultures actively hunt prey, this means they must be able to make contact with their talons onto a moving object, which vultures feeding on carcasses are never going to have to do." Understanding how birds see the world could help inform future sites for structures like wind farms. While the white-headed vulture stand a better chance of avoiding collisions, deliberate poisoning is threatening it and many other vulture species in Africa. It's classed as critically endangered, with a very high risk of extinction.