18 Dec 2008

13th Dec 1988 - Vultures

We are surrounded by thick cloud again this morn­ing and have to go down the road some way to get under it. Surprisingly griffons are amongst the first birds to be seen, floating along level with the cloud base, about thirty in all.

At night these vultures roost communally in loose groups, usually on cliff ledges or rock outcrops. They leave as soon as temperatures rise suffic­iently or wind currents are adequate for soaring. But on misty mornings, like today, they may not vacate the site until ten or eleven o'clock and birds may stay put when it is wet or foggy. The members of a colony fly off together up to sixty kilometres in one direction, then they split up and apparently each individual systematically circles one area, searching the ground but still keeping an eye on its neighbours just in case they find food first.

After a rather circuitous journey we manage to get onto rough ground above farmland, and then we see the vultures descending on something just over the ridge and out of our sight. Vul­tures are attracted to a carcass by sight, and often by the movements of other birds on the ground or in the air ‑ here crows, ravens and magpies are also in attendance. A hundred or more vultures may alight some distance from the food and approach timidly. We see at least ten birds on the ground and another fifteen in the air. Those on the ground appear to be pulling at something while others appear to be defending themselves - or their meal.

Natural history films often show vultures feeding together in a squabbling mass, but this only happens if all the birds are equally hungry -and it looks more exciting on film. Usually they take turns, the hungriest birds first while others queue up and wait. Feeding birds maintain their positions by threatening, chasing and fighting others. Fights, which are usually brief and highly ritualised, also break out amongst the nearest onlookers. After feeding for several minutes a bird at the carcass may be displaced by a hungrier one from nearby group. Many gorge so much that they are unable to take off and may have to eject part of meal before flying.

We walk up a jeep track to level with the cloudbase, which had by then risen to about 950 metres, passing a plantation of what appeared to be cupressus sp. and Monterrey pine, eventually emerg­ing in an area of heather, gorse and grass. A few ponies and cattle graze the hills, but there are no sheep at this time of year. Higher up there is deciduous woodland ‑ beech, alder and Pyrenean oak. There are few small birds, apart from half a dozen siskin around the alders and flying into a crevice contain­ing only mosses so far as we could see.

By the time we reach the place where the vultures were feeding, they have dispersed; a high fence and locked gate prevent us from see­ing what they had been feeding on.

Traditionally, each community had its own "mule tip", a place where they took mules, cattle, etc when they died and left the bodies to be cleaned up by the vultures. This practice is dying out as farmers prefer to bury the carcasses in pits and use a chemical to speed up the decom­position pro­cess. These pits are actually illegal and are depriving the vultures of food. People studying vultures now sometimes provide carcasses at conv­enient places, and in recent years the vulture population has increased by up to 400% in some areas. As this particular area was fenced off, we might have come across either a mule tip, or a study area here.

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