They are different from other birds of prey, but at first glance they somehow resemble them with their curved beak. Birds of prey (the "daily" birds, typical representatives being eagles, hawks, falcons, etc. and the "night" birds, which are owls) catch their prey in the air or on the ground, killing it by a blow or tightening of claws and eating it by using the beak, while holding it with their legs or with the claws.
Griffon vultures have the so called "false eyes", which is the bare spot on their chest, surrounded by "woolly" feathers, forming a necklace. With these "eyes" they indicate their mood, anger, desire for domination, by changing its colour from gray (elder specimen) or pink in younger griffons to bright and dark red to green, blue and purple.
Almost all vultures feed exclusively on other vultures and are interested in individual body parts. As a rule, they do not attack live prey. However, weak animals can be an exception when vultures are very hungry or if the number of birds is large. This is common in Spain, where there live about 18,000 pairs. Their basic food are carrions of large herbivores (cattle, horses, donkeys, sheep, goats, etc.), but also small mammals: rabbits and fox. They mostly eat soft visceral tissues. On the island Cres they were observed eating a dead dolphin which had been thrown onto shore.
Among the vultures these are the biggest birds on our planet: on one part of the world there are the Himalayan vulture (Gyps himalayensis) and the cinereus vulture (Aegypius monachus), and on the other part of the world the Andean condor and the Californian condor, which all weigh more than 12 kg, with the wing span of over 3 meters (some even over 3.10 m). Also the Croatian griffon vultures which are much heavier than the Spanish ones belong to this group. It is not uncommon that they weigh more than 12, 13 or even 14 kilos.
As the quantity of available carcass is unpredictable they developed a specific way of feeding. They are looking for food using only their vision forming a group called a "comb" or a "network", in which the distance between the griffons is one kilometre or even more. They can see each other from a distance of 12 kilometres and they can spot a carcass of a sheep from a height of 6 km, simultaneously surveying an area of 100 square kilometres, in search for carcasses.
Today, perhaps 90% of griffon vultures live in Spain, where their number has reached 18,000 pairs. Also in Spain vultures feed predominantly on carcasses, so the amount of available food influences their number and colonisation. They predominantly feed on horses, donkeys and mules, the number of which in the highlands of the Pyrenees reached about 2.5 million.
A differentiation of single birds within the same colony is possible and it is important (it has been noted that birds are able to recognize if a certain bird belongs to another colony or another population). Every time when they share a meal according to these characteristics a very "precise" social hierarchy is established.
Older griffons which are also more experienced and more dominant usually eat first. By spreading their wings, lifting one leg, stretching their necks and "hissing" they want to sign that ʺthe prey belongs only to them", even willing to fight for their prey, until the rival lands on its back, demonstrating submission.
However, griffon vultures are basically social animals, so their aggressiveness and their desire for the domination decreases with the number of snacks eaten, and gradually also the younger males, and later on the females are allowed to eat, and in the end (if there is enough food) also the juvenile vultures. They have found the food together, so it is ok that each one gets at least a few bites food. Birds of the first age classes (one-year, two-year, three-year vultures) are waiting, doing concentric circles around the carcass. They are the ʺcandidatesʺ. They are waiting during the battle for domination between the older, adult birds. The importance of hierarchical relationships among vultures, which live in large groups and depend on each other, is demonstrated in the differences between vultures of a different age category. Basing on their age, their beaks and eyes are of different colour, the shape of the necklace is different and even the colour of their feathers varies.
The anatomy of vultures is specially adapted for flying, because the search for food requires long hours of sailing, surveying hundreds of square miles of land.
Interesting fact: Vultures are able to fly for days, leaving behind thousands of kilometres without eating. However, they are not able to fly by moving their wings – in such way they would be able to fly just 15 kilometres, spending so much energy as a robin crossing 2,250 kilometres.
Therefore vultures fly by making use of air currents, while spending 30 times less energy than when flying actively. Their wing span of nearly 3 meters (2.60 to 2.80 m) is an advantage, because they can make use of air currents in the atmosphere ("air corridors"), in the same way as gliders. Otherwise it would not be possible for them to fly. Their weight of more than 10 kg implies strong pectoral muscles in order to move such large wings. These strong pectoral muscles would then again add to bird weight, which would require larger wings, and then again stronger muscles, and so on. Therefore the size of this kind of birds: the griffon vulture, the cinereus vulture or the Andean condor – is the largest possible, when still being able to fly. Their flying speed is up to 160 km/h, but when they are surveying the grounds in search of food they usually fly at a speed of about 40–75 km/h.
Interesting fact: The flight of the griffon vulture is one of the most impressive natural phenomena and is literally breathtakingly beautiful – so simple and yet so perfect. The flight of the Andean condor is described in the famous song 'El Condor pasa' as: "It is breathtaking to see a condor flying ..." However, the flight of a griffon vulture on the bora wind above the sea is even more fascinating …