Himalayan vulture
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The Himalayan vulture (Gyps himalayensis) or Himalayan griffon vulture is an Old World vulture native to the Himalayas and foothills in North and Northeastern India, as well as the adjacent Tibetan Plateau. After the cinereous vulture (Aegypius monachus), it is the second-largest Old World vulture species, and among the world's largest true raptors. It is listed as Near Threatened on the IUCN Red List.<ref name=iucn /> It is not to be confused with the Eurasian griffon vulture (Gyps fulvus), which is a visually similar, sympatric species.<ref>Template:Cite journal</ref>
DescriptionEdit
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The Himalayan vulture has dark brown greater covert feathers, tail and wing quills, but a pale buff uniform upperside and paler tipped inner secondaries; its legs are covered with buffy feathers and vary in colour from greenish grey to pale brown. The underside and under-wing coverts are pale brown or buff, almost white in some individuals. The whitish down on the head of immatures changes to yellowish in adults who have a long and pale brown ruff with white streaks and long and spiky ruff feathers.<ref name="Brown">Template:Cite book</ref>
The pale blue facial skin is lighter than the dark blue in Gyps fulvus with this species having a yellowish bill. In flight the long fingers are splayed and there is a pale patagial stripe on the underwing. The wing and tail feathers are dark and contrast with the pale coverts and body, one of the best methods to distinguish this species from the slightly smaller griffon vulture.<ref name=pcr>Template:Cite book</ref><ref>Template:Cite journal</ref> The feathers on the body have pale shaft streaks.<ref name="Brown"/><ref name=fbi2>Template:Cite book</ref><ref name=fbi1>Template:Cite book</ref>
It is the largest of the Gyps species, averaging larger in every method of measurement than its relatives, and is perhaps the largest and heaviest bird in the Himalayas.<ref name=RaptorsWorld/> Weight in Himalayan vultures ranges from Template:Cvt<ref>Template:Cite journal</ref> to Template:Cvt.<ref>Template:Cite book</ref> It has been estimated to weigh an average of Template:Cvt, but weights vary with conditions from Template:Cvt.<ref name=RaptorsWorld/><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> Published measurements of the wingspan vary from Template:Cvt, a similar range to that of cinereous vulture,<ref name= RaptorsWorld/><ref name="Brown"/> but the wingspan varies greatly depending on the method used to measure them.<ref>Template:Cite journal</ref>
It differs from the similar-coloured Indian vulture (G. indicus) by a stouter, more robust bill; younger birds have a pale bill and tend to have buffy-white streaks on the scapulars and wing coverts contrasting with dark brown underparts.<ref name="Brown"/> It is similar in size to the cinereous vulture (Aegypius monachus), which typically has a slightly shorter overall length but can weigh more than the Himalayan vulture.<ref name=RaptorsWorld>Template:Cite book</ref><ref name="HBW">Template:Cite book</ref>
DistributionEdit
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The Himalayan vulture lives mainly in the higher regions of the Himalayas and the Tibetan Plateau at the elevation range of Template:Cvt. It is distributed from Kazakhstan, Uzbekistan, Kyrgyzstan, Tajikistan, Afghanistan and Iran to Pakistan to India, Nepal, Bhutan to western China and Mongolia.<ref name=iucn /> Juvenile birds may however disperse further south, and vagrants have been recorded in Thailand, Burma, Singapore and Cambodia.<ref>Template:Cite journal</ref>
Behaviour and ecologyEdit
DietEdit
The Himalayan vulture perches on crags, favourite sites showing white marks from regular defecation. They tend to not range below an elevation of Template:Cvt.<ref name="Brown"/> Himalayan vultures often bask in the sun on rocks. They soar in thermals and are not capable of sustained flapping flight. Flocks may follow grazers up the mountains in their search for dead animals. This vulture makes a rattling sound when descending on a carcass and can grunt or hiss at roosts or when feeding on carrion.<ref name=pcr/> While feeding, individuals may make cackling sounds to defend their food from other vultures or even reprimand them. They are social birds, and are hence found in large flocks, while even being accompanied by crows (observed with other vulture species as well). Such crows cannot interfere with the flocks (as vultures are physically larger and stronger than crows), but vehicular traffic, human interference, and attacks from herding dogs can pose a disturbance.
They have been recorded eating carrion exclusively, some which is fed on even when putrid.<ref name="Brown" /> On the Tibetan Plateau, it was noted that 64% of their diet was obtained from deceased domestic yak (Bos grunniens).<ref name="tibet" /> The birds fed on old carcasses, sometimes even waiting for several days near a dead animal.<ref name="pcr" /><ref name="hbk">Template:Cite book</ref> However, each vulture species has a specialty diet: Himalayan vultures largely disdain offal (which is readily eaten by other vulture species), typically eating only fleshy tissue.<ref name="Brown" /> Historically, Himalayan vultures regularly fed on human corpses left out on Celestial burial grounds.<ref name="Brown" />
The Himalayan vulture is fairly defensive around other scavengers, such as foxes or smaller felines, and typically dominates other meat-eaters at carcasses, though it is subservient to gray wolves (Canis lupus), snow leopards (Panthera uncia) and cinereous vultures (Aegypius monachus).<ref name="Brown" /> In a large party, these vultures can reportedly strip a carcass of all tissue in 30 minutes, and do the same to a yak carcass in roughly 120 minutes.<ref name="Brown" /> Himalayan vultures have been observed feeding on pine (Pinus roxburghii) needles, an unexplained behaviour that cannot be for obtaining nutrition, but may be done to access essential oils and terpenes in the needles for digestive or immunity benefits.<ref>Template:Cite journal</ref>
BreedingEdit
The breeding season begins in January. The nest is a platform of sticks placed on an inaccessible ledge on a cliff. Nest in northeastern India have been recorded at between Template:Cvt in elevation, but those in Tibet have been as high as Template:Cvt.<ref name="Brown"/> Several pairs may nest on the same cliff face, with between five and seven pairs being a typical colony size.<ref name="Brown"/> The nests are relatively small for the large size of these birds and, although grow larger with repeated uses, do not generally get as massive as the nest of other large accipitrids.<ref name="Brown"/> There is at least one recorded instance of Himalayan vultures using a nest made by bearded vultures (Gypaetus barbatus).<ref name="Brown"/> On the Tibetan Plateau, Himalayan and bearded vultures were observed nesting in close proximity without conflict, which is notable because in several other cases of adjacent interspecies nesting by Old World vultures (including some involving bearded vultures) have resulted in high aggression and interspecies attacks.<ref>Template:Cite journal</ref> A single white egg marked with red splotches is the usual clutch.<ref name=hbk/> Egg laying dates in northern India have ranged from December 25 to March 7.<ref name="Brown"/> The egg is coarse and oval and can measure from Template:Cvt in height and Template:Cvt in width, with an average of Template:Cvt.<ref name="Brown"/> In captivity the incubation period was about 54–58 days. The young birds stay on with the parents for six to seven months.<ref>Template:Cite journal</ref>
ThreatsEdit
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Himalayan vultures are susceptible to toxicity induced by diclofenac, a drug whose residues in domestic animal carcasses has led to rapid declines in populations of other Gyps vultures across Asia.<ref>Template:Cite journal</ref> The Himalayan griffon vulture populations have however not shown signs of rapid decline,<ref name=tibet>Template:Cite journal</ref> although reductions in nesting birds have been noted in some parts of its range in Nepal.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
ReferencesEdit
External linksEdit
- Himalayan griffon vulture videos Template:Webarchive. The Internet Bird Collection