Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Himalayan Vulture - Gyps himalayensis
Himalayan Vulture - Gyps himalayensis

[Image: Himalayan_Vulture_%28by_a_road%29_%282926948182%29.jpg]

Scientific classification
Kingdom:  Animalia
Phylum:  Chordata
Class:  Aves
Order:  Accipitriformes
Family:  Accipitridae
Genus:  Gyps
Species:  Gyps himalayensis  Hume, 1869

The Himalayan vulture or Himalayan griffon vulture (Gyps himalayensis) is an Old World vulture in the family Accipitridae. Closely related to the European Griffon Vulture (G. fulvus) and once considered a subspecies of it, this species is found along the Himalayas and the adjoining Tibetan Plateau. It is one of the two largest Old World vultures and true raptors.

Length: 1,030–1,150 mm (40.6–45.3 in)
Culmen: 71–77 mm (2.8–3.0 in)
Wing: 755–805 mm (29.7–31.7 in)
Tail: 355–405 mm (14.0–15.9 in)
Tarsus: 110–126 mm (4.3–5.0 in)

This is a huge vulture, and is perhaps the largest and heaviest bird found in the Himalayas. Adults have a ruff that is long and pale brown with white streaks. The ruff feathers are long and spiky. The head is covered in down which is yellowish in adults but whitish in immature vultures. The underside and under-wing coverts are quite pale brown or buff, being almost white in some specimens. The legs are covered with buffy feathers and the feet can vary from greenish grey to white. The upperside is unstreaked, pale buff with the tail quills, outer greater coverts and wing quills being a contrasting dark brown. The inner-secondaries have paler tips.

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. The feathers on the body have pale shaft streaks. They are distinguished from the Indian vulture (G. indicus), which can somewhat similar in color by being much larger with a stouter, more robust bill. Younger birds have a pale parts to the bill and tend to have buffy-white streaks on the scapulars and wing coverts contrasting with dark brown underparts. They are similar in size to the Cinereous Vulture (Aegypius monachus), which has a slightly shorter overall length but in large specimens can weigh more than the Himalayan vulture. Weight in Himalayan vultures can range from reportedly as little as 6 kg (13 lb) to as much as 12.5 kg (28 lb). A field study estimated an average of 9 kg (20 lb) for the Himalayan vulture, but weights can vary with conditions from 8–12 kg (18–26 lb). The wingspan of birds varies greatly depending on the method used to measure them and published measurements vary from 2.56 to 3.1 m (8.4 to 10.2 ft), a similar wingspan range as a Cinereous Vulture.

The species is found mainly in the higher regions of the Himalayas, the Pamirs, Kazakhstan and on the Tibetan Plateau (technically in China), with northwestern limits of the breeding range being in Afghanistan and southern limits in Bhutan. Juvenile birds may however disperse further south and vagrants have been recorded in Thailand, Burma, Singapore and Cambodia.

[Image: 220px-GypsHimalayensisMap.svg.png]

Behaviour and ecology

The Himalayan vulture perches on crags, favourite sites showing white marks from regular defecation. They tend to not range below an elevation of 1,215 m (3,986 ft). 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. They have been recorded eating carrion exclusively, some which is fed on even when putrid. On the Tibetan Plateau 64% of their diet is obtained from dead domestic Yak (Bos grunniens). They feed on old carcasses sometimes waiting a couple of days near a dead animal. They disdain offal, which is readily eaten by other vultures, and instead typically eat only fleshy parts. Historically, Himalayan vultures regularly fed on human corpses left out on Celestial burial grounds. This species is fairly contentious around other scavengers and typically dominates other meat-eaters at carrion, though is subservient to Gray Wolves (Canis lupus), Snow Leopards (Panthera uncia) and Cinereous Vultures at carcasses. In a large party, these vultures can reportedly strip a human or sheep carcass of all meat in 30 minutes and do the same to a yak carcass in roughly 120 minutes. Himalayan vultures have been observed feeding on pine (Pinus roxburghii) needles, an unexplained behaviour that cannot be for obtaining nutrition.

[Image: 1600px-Himalayan_griffon_%28Gyps_Himalay..._Spiti.JPG]

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 1,215 and 1,820 m (3,986 and 5,971 ft) in elevation, but those in Tibet have been as high as 4,245 m (13,927 ft). Several pairs may nest on the same cliff face, with between five and seven pairs being a typical colony size. 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. There is at least one recorded instance of Himalayan vultures using a nest made by Bearded Vultures (Gypaetus barbatus). 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. A single white egg marked with red splotches is the usual clutch. Egg laying dates in northern India have ranged from December 25 to March 7. The egg is coarse and oval and can measure from 87 to 103.6 mm (3.43 to 4.08 in) in height and 65 to 74 mm (2.6 to 2.9 in) in width, with an average of 94.8 by 70.1 mm (3.73 by 2.76 in). In captivity the incubation period was about 54–58 days. The young birds stay on with the parents for six to seven months.

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. The Himalayan griffon vulture populations have however not shown signs of rapid decline although reductions in nesting birds have been noted in some parts of its range in Nepal.

Study shows how vultures evesdrop to gather vital flight information
Social network helps birds pick best way of using thermal updrafts

Date:  November 7, 2018
Source:  Swansea University

[Image: 181107130309_1_900x600.jpg]
Footage of a vulture in flight caputred during the research.
Credit: Hannah Williams

A new study has revealed how vultures use their very own social networks to work out the best way to take advantage of thermal updrafts to help them fly vast distances.
The research, carried out by a team from Swansea University led by PhD student Hannah Williams, examined how the vultures seemed to make risky but efficient choices in flight when they observed the flight of other vultures in the network.
Their paper Social eavesdropping allows for a more risky gliding strategy by thermal soaring birds has just been published in the Journal of the Royal Society Interface and Hannah hopes it will help provide a better understanding about the strategies birds use to navigate the aerial landscape.
She said: "Thermal updrafts are chaotic in their occurrence, so it makes sense for these heavy birds to 'eavesdrop' on the movements of other birds to find thermals, just as human pilots do when gliding.
"We worked with Dr Olivier Duriez, of the University of Montpellier, to track the movements of five vultures at a bird of prey centre in France, using special tag technology contained in backpacks worn by the birds.
"We hypothesised that birds would fly towards areas where other birds had been circling and that they would do so at fast speeds. It is a risky flight strategy to glide at fast speeds, but it appears they may take this risk when using information from the network."
Working with her co-authors from the Swansea Laboratory for Animal Movement and SHOALgroup, both based in the University's Biosciences Department, Hannah explained that the research data was collected in just three days but it had taken more than six months to design the necessary tracking experiment and the tag technology.
She said: "This is part of a multi-year collaboration and the design of the tags, which notably collect high-frequency airspeed data, has been a long and challenging process.
"From here we hope to delve further into how birds may acquire information from other birds in the sky, to make better movement choices. "
Co-author Dr Andrew King, of the Department of Biosciences, said: "We are used to hearing about how flocking species like pigeons and starlings use social information. This data, gathered simultaneously from a number of soaring vultures, provides a great example how relying on others for information can be beneficial at a very different spatio-temporal scale."
Hannah, from Lancashire, completed her doctorate last year after studying with the Swansea Laboratory for Animal Movement and SHOAL. She said: "This publication was the project that brought all the aspects of my PhD together -- animal attached logging devices, flight dynamics and social behaviour.
"Thanks to a great set-up in France using captive birds that could fly freely each day and a team of hardware engineers and movement specialists at Swansea University, we were able to collect the high-frequency flight data needed to investigate this eavesdropping behaviour."
She now plans to continue her research into animal movement at the University, working with Dr Emily Shepard, from the College of Science, studying flight patterns of condors.

Story Source:  Swansea University. "Study shows how vultures evesdrop to gather vital flight information: Social network helps birds pick best way of using thermal updrafts." ScienceDaily. (accessed November 8, 2018).

Journal Reference:
  1. Hannah J. Williams, Andrew J. King, Olivier Duriez, Luca Börger, Emily L. C. Shepard. Social eavesdropping allows for a more risky gliding strategy by thermal-soaring birds. Journal of The Royal Society Interface, 2018; 15 (148): 20180578 DOI: 10.1098/rsif.2018.0578
Vultures are thought to form networks in the sky, with individuals monitoring the movements of others to gain up-to-date information on resource availability. While it is recognized that social information facilitates the search for carrion, how this facilitates the search for updrafts, another critical resource, remains unknown. In theory, birds could use information on updraft availability to modulate their flight speed, increasing their airspeed when informed on updraft location. In addition, the stylized circling behaviour associated with thermal soaring is likely to provide social cues on updraft availability for any bird operating in the surrounding area. We equipped five Gypsvultures with GPS and airspeed loggers to quantify the movements of birds flying in the same airspace. Birds that were socially informed on updraft availability immediately adopted higher airspeeds on entering the inter-thermal glide; a strategy that would be risky if birds were relying on personal information alone. This was embedded within a broader pattern of a reduction in airspeed (approx. 3 m s−1) through the glide, likely reflecting the need for low speed to sense and turn into the next thermal. Overall, this demonstrates (i) the complexity of factors affecting speed selection over fine temporal scales and (ii) that Gyps vultures respond to social information on the occurrence of energy in the aerial environment, which may reduce uncertainty in their movement decisions.
[Image: wildcat10-CougarHuntingDeer.jpg]
[-] The following 1 user Likes Taipan's post:
  • Claudiu Constantin Nicolaescu

Forum Jump:

Users browsing this thread: 1 Guest(s)