Cinereous Vulture - Natural History

Natural History

The Cinereous Vulture is a largely solitary bird, being found alone or in pairs much more frequently than most other Old World vultures. At large carcasses or feeding sites, small groups may congregate. Such groups can exceptionally include 12 vultures, with unconfirmed reports of up to 30 in very old reports.

They breed in loose colonies, with nests rarely being found in the same tree or rock formation, unlike other Old World vultures which often nest in tight-knit colonies. In Spain, nests have been found from 300 m (980 ft) to 2 km (6,600 ft) apart from each other. The Cinereous Vulture breeds in high mountains and large forests, nesting in trees or occasionally on cliff ledges. The breeding season lasts from February until August or September. The commonest display consists of synchronous flight movements by pairs. However, flightplay between pairs and juveniles is not unusual, with the large birds interlocking talons and spiraling down through the sky. The birds use sticks and twigs as building materials, and males and females cooperate in all matters of rearing the young. The huge nest is 1.45–2 m (4.8–6.6 ft) across and 1–3 m (3.3–9.8 ft) deep. The nest increases in size as a pair uses it repeatedly over the years and often comes to be decorated with dung and animal skins. The nests can range up to 1.5 to 12 m (4.9 to 39 ft) high in a large tree such as an oak, juniper, almond or pine trees. Most nesting trees are found along cliffs. The egg clutch typically only a single egg, though 2 may be exceptionally laid. The incubation period can range from 50 to 62 days, averaging 50–56 days. The newly hatched young are semi-altrical. Fledging is reported when the nestlings are 104–120 days old, though dependence on parents can continue for another 2 months. Radio-satellite tracking suggests the age of independence of juveniles from their parents to be 5.7–7 months after hatching (i.e. 2–3 months after fledging. The nesting success of Cinereous Vultures is relatively high, with around 90% of eggs successfully hatching and more than half of yearling birds known to survive to adulthood. They are devoted, active parents, with both members of a breeding pair protecting the nest and feeding the young via reguritation in shifts. This species may live for up to 39 years, though 20 years or less is probably more common, with no regular predators other than man.

Like all vultures, the Cinerous Vulture eats mostly carrion. The Cinereous Vulture feeds on carrion ranging from the largest mammals available to fish and reptiles. In Tibet, commonly eaten carcasses can include both Wild and Domestic Yaks, Bharal, Tibetan Gazelles, Kiangs, Woolly Hares, Himalayan Marmots, Domestic Sheep and even humans, mainly those at their celestial burial grounds. Reportedly in Mongolia, Tarbagan Marmots comprised the largest part of the diet, although that species is now endangered as it is preferred in the diet of local people. Among the vultures in its range, the Cinereous is best equipped to tear open tough carcass skins thanks to its powerful bill. It can even break apart bones, such as ribs, to access the flesh of large animals. It is dominate over other scavengers in its range, even over other large vultures such as Griffon Vulture or fierce ground predators such as foxes. While noisy Gyps vultures squawk and fly around, the often silent Cinereous will keep them well at bay until they are satisfied and have had their own fill. Its closest living relative may be the Lappet-faced Vulture, which takes live prey on occasion. Occasionally, the Cinereous Vulture has been recorded as preying on live tortoises, which the vultures are likely to kill by carrying in flight and dropping on rocks to penetrate the shell, and lizards. Additionally, Cinereous Vultures have been recorded as flying low around herds of Argali with females and lambs, possibly seeking to predate the lambs.

This species can fly at a very high altitude. It has a specialised haemoglobin alphaD subunit of high oxygen affinity which makes it possible to take up oxygen efficiently despite the low partial pressure in the upper troposphere.