|Adult Griffon Vulture (Martin Kelsey)|
The second sensual impression was an assault of sound, a wheezing, baying and moaning which echoed across the small gorge. Unlike the barrage of sound typical of seabird colonies, this could be pinpointed to specific locations. There one beheld the spectacle of vigorous copulation between these massive birds. The male perched on top of the female, their tails swivelled to ensure the meeting of cloacas, This was not the split-second flurry typical of most birds. It was a heaving noisy union which lasted impressively close to a minute.
Mid-December and the breeding season of the Griffon Vultures was already underway. Indeed as we scanned the gorgeous architecture of these ancient rocks, we found at least one pair of birds where whilst one stood the other was sitting tight on the nest, apparently already incubating their single egg. My friend, Ángel Sanchez, who is a senior conservationist in the government of Extremadura, as well as being an excellent ecologist and naturalist, has described the fascinating ecological differences that drive the different breeding cycles of our two largest carrion feeders: the Griffon and Black Vultures. Griffon Vultures feed on the carcases of large herbivores, be they wild (deer or boar) or livestock such as sheep or cattle. For these species the mortality rates are highest in late summer to early winter. Black Vultures, on the other hand, nesting in trees and colonial in only a very loose way, and tending to be more solitary by nature, evolved to feed on smaller prey, especially rabbits. On a visit this week to the Lacañada Hide where animal remains had been laid out to lure-in vultures, it was the Griffons which poured in like a frenzied scrum to disintegrate a whole carcase in minutes, whilst the Black Vultures moved in to feed on the scattered remains and morsels that the Griffon Vultures had disregarded.
|Black and Griffon Vultures (Martin Kelsey)|