Grifone di Rüppell

Identificazione

The Rüppell's vulture is a large vulture, noticeably outsizing the closely related white-backed vulture, with which they often occur in the wild. Adults are 85 to 103 cm (33 to 41 in) long, with a wingspan of 2.26 to 2.6 m (7 ft 5 in to 8 ft 6 in), and a weight that ranges from 6.4 to 9 kg (14 to 20 lb). Both sexes look alike: mottled brown or black overall with a whitish-brown underbelly and thin, dirty-white fluff covering the head and neck. The base of the neck has a white collar, the eye is yellow or amber, the crop patch deep brown. The head does not have feathers. This is an adaptation that occurred because of the Rüppell vulture's tendency to stick its head inside of its prey when eating. Without the adaptation, feeding would become extremely messy. Silent as a rule, they become vocal at their nest and when at a carcass, squealing a great deal. Rüppell's vultures commonly fly at altitudes as high as 6,000 m (20,000 ft). The birds have a specialized variant of the hemoglobin alphaD subunit; this protein has a great affinity for oxygen, which allows the species to absorb oxygen efficiently despite the low partial pressure in the upper troposphere. A Rüppell's vulture was confirmed to have been ingested by a jet engine of an airplane flying over Abidjan, Ivory Coast on 29 November 1973 at an altitude of 11,300 m (37,000 ft).

Tassonomia

Nome scientifico

Gyps rueppelli

Autorità

(Brehm, AE, 1852)

Ordine

Accipitriformi

Famiglia

Accipitridae

Genere

Gyps

Areale e habitat

Rüppell's vulture is distributed throughout the Sahel region and East Africa, where it inhabits grasslands, mountains, and woodlands. Once considered common in these habitats, it is experiencing steep declines, especially in the western portion of the range.

Migrazione

Complete migrants

Comportamento

It cruises at a speed of 35 km/h (22 mph), but flies for 6–7 hours every day and as far as 150 km (93 mi) from a nest site to find food.[citation needed]<p>Strictly a carrion feeder, the Rüppell's vulture has been known to follow game herds on their seasonal migrations and feeds in large numbers at carcasses, usually with other Old World vulture species. Though it might take advantage of the remains of an animal killed by a lion, or other large predator, it can also feed on animals that have died from injuries, disease, or old age. Though they prefer freshly-killed meat, they can eat older carcasses without a problem. Rüppell's vultures have several adaptations to their diet and are specialized feeders even among the Old World vultures of Africa. They have an especially powerful build and, after the most attractive soft parts of a carcass have been consumed, they will continue with the hide, and even the bones, gorging themselves until they can barely fly. They have backward-pointing spikes on the tongue to help remove meat from bone. Despite their size, power and adaptations, they are not the most dominant vulture in their range; the most dominant species is considered to be the larger lappet-faced vulture.<p>This species of vulture is considered to be monogamous, forming lifelong breeding pairs. After courtship the pair will work together to build a nest using sticks, grass, and leaves that they have gathered or stolen from other nests. Rüppell's vultures build these nests on cliffs, and in key breeding areas they are known to nest in large colonies containing hundreds of breeding pairs. Both parents share in incubation of their egg over a period of 55 days. Once the chick hatches, both parents will feed and tend to it for about 150 days when it fledges. Young remain dependent on their parents after fledging, not reaching independence until the next breeding season. During this time they learn how to find and compete for food.

Conservazione

Since first being assessed by the International Union for Conservation of Nature in 1988, populations of Rüppell's vulture have decreased. The species has been listed with an IUCN Red List status of "near threatened" since 2007, and populations are estimated to decline. From 2012 to 2014 the Rüppell's vulture was listed as Endangered; however, it was reassessed in 2015 as Critically Endangered.<p>Rüppell's vulture is currently listed as an Appendix II species under CITES, which regulates the international trade of animals and plants. Under this designation, the Rüppell's vulture is defined as not being immediately at risk of extinction, although the current population could become threatened without a careful regulation of trade.<p>The total population of Rüppell's vulture has been estimated to be somewhere around 22,000 individuals, with specific populations in the following areas: Tanzania (3,000 pairs); Kenya (2,000 pairs); Ethiopia (2,000 pairs); Sudan (2,000 pairs); and West Africa (2,000 pairs).<p>Since 1992, Rüppell's vulture has been occurring as a vagrant in Spain and Portugal, with annual records since 1997, mainly in the Cádiz and Strait of Gibraltar area, but also further north.

Tendenza della popolazione

declining