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November, 2009Research in Environment and Life Sciences 185
Nature’s scavengers: Vultures
Sonika Kushwaha1, Amita Kanaujia*1 and Dhruvjyoti Basu2
1Department of Zoology, University of Lucknow , Lucknow-226 007, India2Gharial Conservation Alliance, Uttar Pradesh, India
*e-mail: kanaujia.amita@gmail.com
(Received: May 18, 2009; Revised received: September 15, 2009; Accepted: September 29, 2009)
Abstract: The current status of vultures once again highlights the results of human follies. It is evident that the Asian vultures are disappearing faster than the
dodo-and like them a victim of human activities. The toll on the vultures has been enormous. Mortalities have been recorded across many parts of India,
Pakistan and lowland Nepal. They are vanishing from Indian skies at an alarming pace due to a number of reasons. Diclofenac, a widely used medicine for
both humans and livestock of the non-steroidal anti-inflammatory group of drugs (NSAIDS) has been identified as the main culprit for the vulture toll. The Indian
Government banned Diclofenac in March 2006. A number of captive breeding centers are being established in India and other countries for the endangered
species.
Key words: Vultures, Breeding, Natural scavengers, Incinerators
Res. Environ. Life Sci.
ISSN: 0974-4908 2(4) 185-192 (2009)
http://www.rels.comxa.com rel_sci@yahoo.com
Review Paper
Introduction
In the past centuries man has altered the world he lives
in. The natural effect of all his activities have resulted in the
destruction of some of the animals in a habitat and greatly increased
the populations of other. A recent example of this is the precipitous
decline in Gyps vulture population in India and its neighbouring
countries.There are 22 kinds of vultures which includes 15 types of
Old World vultures and 7 types of New World vultures (Fig. 6).
There are nine species of vultures found in India: King vulture
(Sarcogyps calvus), Cinereous vulture (Aegypius monachus),
Griffon vulture (Gyps fulvus), Himalayan Griffon vulture (Gyps
himalayensis), Long-billed vulture (Gyps indicus), Slender-billed
vulture (Gyps tenuirostris), White-backed vulture (Gyps
bengalensis), Egyptian vulture (Neophron percnopterus), and
Bearded vulture (Gypaetus barbatus (Ali, 1995; Birdlife International,
2007a,b,c; Gadhvi and Dodia, 2006; Parsi, 2009). It is evident that
the Asian vultures are disappearing faster than the Dodo-and like
them a victim of human activities. They are also highly sensitive to
environmental changes (Houston, 1974). The ecological extinction
of Gyps vultures in India is also leading to further changes in the
species complement of scavengers. Important zoonotic diseases,
such as rabies and bubonic plague, which are endemic within
India and for which dogs (Canis spp.) and rats (Rattus spp.),
respectively, are the primary reservoirs, are likely to increase as
a consequence of the vulture declines (Pain, 2003). Wildlife and
domestic livestock may also be at increased risk from dog and rat-
borne pathogens, including canine distemper virus, canine
parvovirus and Leptospira species bacteria. Vultures probably
also help to control livestock diseases such as brucellosis,
tuberculosis, and anthrax by disposing of infected carcasses
(Prakash, 1999). They come to the rescue of man to dispose of
carcasses when animals die during natural calamites such as
floods, storms, drought and war. By cleaning carcasses of dead
animals, they act as the sanitation department of the natural
world.
In 2006, it was stated that vultures are dying on a big scale
due to diclofenac poisoning. Diclofenac injection is widely used in
cattle and other animals as an effective anti-inflammatory and pain
relieving medication (Fig. 1). When such animals die vultures attack
the carcasses of these animals and the residual diclofenac from
these dead animal tissues causes widespread lethal renal failure in
vultures (Lawate,2006). Identifying the cause of the Asian vulture
decline gives hope to many conservationists working to save these
critically endangered species. This includes Birdlife Partners such
as the Bombay Natural History Society, Ornithological Society of
Pakistan, Bird Conservation Nepal and the RSPB (Royal Society
for Protection of Birds). Other conservation organizations working
hard alongside BirdLife include the Zoological Society of London
(ZSL), and the Peregrine Fund.
Scavengers at a glance
The scavenger’s have bare heads i.e. featherless. This is
again an adaptive feature since they prevent the fouling of feathers
during feeding. The beaks are long and hooked to feed upon the
carcasses (Fig. 2). They are operated by well developed
manidibular muscles and easily tear open the flesh. They tear the
carcass and pick the bones nearly clean. Some vultures have
other adaptations as a result of their feeding strategy.
Vulture’s toes are weak, poorly padded and have only
slightly curved talons (Fig. 3). The toes and tarsi are featherless,
thus helping in quick clean up after feeding. A vulture’s foot looks
more like a turkey’s than a hawk’s. But again, the foot reflect’s the
life-style of the bird. Being scavengers vultures need not catch and
November, 2009Research in Environment and Life Sciences 186
Fig. 1: Diagrammatic representation of Diclofenac effect (source: AFP) Fig. 2: Bare heads with hooked beaks
A B
Fig. 3: Vulture toe
Fig. 4: Bath after meal Fig. 5: Sun basking, after the meal
Kushwaha et al.
November, 2009Research in Environment and Life Sciences 187
kill its prey. So they need to balance themselves while feeding on
carcasses. This is easily achieved by their large feet.
Vultures digestive systems have the unique ability to kill
virus and bacteria present in their food. The acidity in the stomach
is so powerful that it breaks down the meat quickly, before any
pathogens have a chance to infect it. The pH levels in their stomachs
is between 1 and 2 (Houston and Cooper, 1975). That measurement
is comparable to gastric and hydrochloric acid from the human
stomach and is more caustic than acid rain. It is also a higher pH
level than the stomach contents of other carnivorous birds, including
herons and barn owls. That acid inside a vulture’s body can also
be wielded as an effective defense mechanism. Their defensive
vomit is foul-smelling enough to drive away predators. If enemies
approach too closely, the high amount of acid in the vomit is strong
enough to burn them as well (Cristen, 2009).
Vultures have a large wing-span so they can easily soar
or sail which is the most remarkable and highly specialized mode of
flight. It rises without loss of kinetic energy. They use thermals to
soar up at high altitudes.
Urohydrosis defines birds excreting on their legs as a means
of cooling themselves. Vultures urinate on their own legs as measure
Natural scavenging vulture, Gyps indicus
Fig. 6: Classification of vultures ( Ali and Ripley, 1995; Collar et al., 2001)
VULTURES
New World Vultures Order
Falconiforms
Family
Cathartidae
Genera, Species1. Cathartes aura
2. Cathartes burrovianus
3. Cathartes melambrotus
4. Coragyps atratus
5. Gymnogyps californianus
6. Sarcorhampus papa
7. Vultur gryphus
RANGE
Canada to Tierra del
Fuego, Southern South
America
Absent in Madagascar, Ceylon, Malayan Islands or Australia
where herd forming mammals are absent
RANGE
Africa, Asia & Europe
GENERA, SPECIES1. Aegypius calvus
2. A.monachus
3. A.occipitalis
4. A.tracheliotus
5. Gypaetus barbatus
6. Gypohierax angolensis
7. Gyps africanus
8. G.bengalensis
9. G.coprotheres
10. G.fulvus
11. G.himalayensis
12. G .indicus
13. Necrosyrtes monacus
14. Neophron percnopterus
15. Sarcorampus papa
Family
Accipitridae
Old World Vultures
ORDER
FALCONIFORMES
November, 2009Research in Environment and Life Sciences 188
of thermoregulation, allowing evapotranspiration to keep heat away
from their bodies. As an added benefit, they have such strong and
chemically potent urine that kill bacteria or parasite clinging to the
birds feet.
Vultures lack a syrinx (Voice box) so they are generally
silent, but they will occasionally hiss or grunt. Vultures have acute
eyesight. They can see large carcasses from several miles. Since
they locate their food by sight, they cannot find it in dense forest.
The males and females have no morphological differences.
Thus it is very difficult to identify their sexes. Vultures are
Monogamous i.e. they pair up for life. They lay just a single egg
each year. A unique feature is that they take a bath after each meal
(Fig. 4). They do this so that the blood from carcasses does not
stay in their feathers or on their skin, infecting the vultures with
diseases.
At each meal the birds will gorge themselves on up to
300-500 g of carrion per day. Once satisfied and have the crop,
throat and neck are distended, they go for sun basking i.e. relax
back on their tails, wings spread to provide balance and mouth
hanging open (Fig. 5). It will be about an hour before the meal is
digested enough for the birds to take flight once more and the take
off is very labour-intensive involving much running and leaping
across the plains
Economic importance: Vultures have an important role in the
natural environment. They are nature’s disposal squads or
“scavengers”. Vultures provide the society with a number of
‘services’, most notably disposal of carrion. These services have
an impact on human health, economic activity and on environmental
quality.
An increase in uneaten carcasses poses a direct threat to
human health because the carrions provide a breeding ground for
potentially pathogenic bacteria leading to the possibility of direct or
indirect infections and are sources of disease, such as anthrax
(Pain et al., 2003). A fall in the vulture population could result in an
increase in feral dog population (Prakash et al., 2003), which in
turn could increase the incidence of animal bites and rabies among
humans. Increases in other scavenger populations may have
significant socio-economic impacts. Rats, feral cats and other species
may increase in numbers, leading to spread of disease. The spread
of rabies is largely attributable to dog populations, but increases in
prevalence rates of other diseases may be an issue. It shows that
there was a marked increase in the dog population during 1987-
1997 coinciding with the period of decline in the vulture population.
The population has increased further since 1997, with it being
estimated that there were over 29 million dogs in India in 2003. A
vulture consumes an average of 0.5 kg day-1, while a healthy dog
is estimated one fifth of its body weight a week, or about 5 kg. This
implies that one vulture less would increase food availability for 0.7
dogs (Markandya et al., 2006).
Also the loss of vultures might contribute to environmental
pollution (air and water) resulting in the increased incidence of
anthrax and water borne diseases among people. Important
economic impacts of vulture decline include the impacts on the costs
to villagers of disposing of carcasses and to collectors of cattle
bones for the fertilizer industry. This latter is an old trade among
India’s poor; vultures effectively and rapidly clean skeletons of all
soft material and facilitate the bone collector’s job, whilst feral dogs
cannot serve as substitutes to vultures because they only scavenge
choice tissues. Finally vultures, are important for their considerable
cultural and religious significance that some communities attach to
their role of disposing of human bodies. Followers of the minority
Parsi faith depend on vultures for disposal of their corposes,
considering the burial or burning of human remains to defile the
elements (Houston, 1990).The demolishing vulture population has
denied the Parsee population their traditional way of disposing their
dead. The consequential impacts include additional costs of disposal
of remains, example the use by the Orthodox Community of solar
reflectors to hasten decay of the bodies or the creation of “vulture
centres” to enable disposal in keeping with tradition. In Mumbai 8
solar concentrations, amount to Rs. 1.6 million (Markandya et al.,
2006).
In some parts of the country vultures are now so scarce
that cremation is being used as an alternative to this traditional
celestial burial.
Wider environmental impacts may include increases in
scavenger populations other than feral dogs and water pollution
due to the fouling of watercourses by rotting carcasses. Vultures
also help to control livestock diseases such as brucellosis,
tuberculosis, and anthrax by disposing of infected carcasses. The
dying out of the vultures would be an irreplaceable loss of a link in
the food chain (Prakash, 1999).
Captive breeding centres for vultures in India : The Ministry
of Environment and Forest has supported vulture conservation
breeding centres at Pinjore (Haryana), Buxa (west Bengal) and
Rani Reserve Forests (Assam) through the respective State
Governments. Funds have been released to different states (Andhra
Pradesh- 41.00 lakhs, Madhya Pradesh-41.00 lakhs, Orissa- 41.00
lakhs, Gujarat-53.30 lakhs, Jharkhand- 41.00 lakhs, Haryana- 38.00
lakhs and Punjab- 16 lakhs) for vulture conservation during the last
five years.
Pinjore, Haryana: Bombay Natural History Society
(BNHS) (2001) in collaboration with the Haryana Forest
Department established, The Vulture Conservation Breeding
Centre at Pinjore, Haryana. The Pinjore centre has 120 vultures
and The centre is funded by the Darwin Initiative for the Survival
of Species Fund of Government of U.K. (2001-2006) and
supported by RSPB, ZSL and National Birds of Prey Trust, U.K.
(Jatayu, 2002-2003).
Kushwaha et al.
November, 2009Research in Environment and Life Sciences 189
Raja Bhat Khawa, west Bengal: India’s second Vulture
Conservation Breeding Centre was set up in December 2005 at
Raja Bhat Khawa, West Bengal jointly by Bombay Natural History
Society and West Bengal Forest Department. The Raja Bhat Khawa
centre has 76 vultures of three species (white-backed, long-billed,
and slender-billed vulture).
Rani, Assam: the Govt. of Assam in collaboration with the
BNHS, Bombay has established a vulture conservation and
Breeding centre at Rani. The Rani centre has 33 vultures of two
species (white-backed and slender-billed vulture).The objectives
of the project is to have 50 pairs of Vultures for breeding with the
ultimate goal to release than in the wild.
Some active groups for vulture conservation in India:
Besides the captive breeding centres, the Gypsophils are also
playing an important role to stop the Mother Nature’s cleaners
from extinction.
Surat (Gujarat): Vulture conservation project is one of the
major projects started by Nature Club Surat in the year of 2005
(Jatayu, 2002-2003). This project was based on 6 simple and
basic steps like:
� Observation in regions where these birds are found, study
their activities and collect appropriate useful data.
� Check the data and Plan as per the study that what are the
steps to be taken in direction of conservation.
� Act as per the plan and situation to carry out direct and indirect
efforts.
� Check out-put, and make sure that all the efforts putting up by
the volunteers is on the right path.
� Contact experts and take corrective Steps if required as per
their experience.
� Continue above 5 steps during through out the project.
Jodhpur (Rajasthan): Dr. Anil Kumar Chhangani from J.N.V
University, Jodhpur (Rajasthan) is doing extensive random surveys
in about 23 districts of Rajasthan since last 6-8 years. He has been
monitoring nesting sites, making census, recording predation, observing
species interaction and locating seasonal migration in Rajasthan. He
is conserving vultures in their natural habitats through the rescue
programmes, involving the Forest Department as well as the localites.
His team has saved more than 30 long-billed and white-rumped
vultures in the last two years in the study area. He aims for monitoring
of breeding sites to locate the nest fallen chicks for rescue and care
and thus increase the breeding success and conservation.
Bundelkhand (Uttar Pradesh and Madhya Pradesh):
Exhaustive surveys are being carried out since 2007 in
Bundelkhand Region by Dr. Amita Kanaujia and Sonika Kushwaha
from University of Lucknow. The study is being carried out with due
permission from the Head Forest Offices of Uttar Pradesh and
Madhya Pradesh. The region stretches over districts of Southern
Uttar Pradesh and Northern Madhya Pradesh. It comprises of
Jhansi, Lalitpur, Jalaun, Hamirpur, Banda and Mahoba in Uttar
Pradesh, and, Sagar, Chattarpur, Tikamgarh, Panna and Damoh
in Madhya Pradesh including parts of Gwalior, Datia, Shivpuri and
Chanderi. The activities are in order to present the overall view of
the vulture situation: to provide the data on status (distribution,
numbers or abundance and threats) of vultures. The study is
tentatively on the following lines :-
� To identify the actual mortality factors responsible for vulture
decline.
� To suggest or find out necessary control measures needed for
the conservation of vultures.
� The study also monitor the remaining wild populations and
lobby for the diclofenac free environment.
� The study aims to evaluate the status, habitat, breeding and
nestling behaviour and feeding habits of vultures.
� Efforts are being made to prevent the disturbance and destruction
of natural habitats aboded by vultures.
� Efforts are also being taken to arrange for safe food for vultures
through vulture restaurants.
Katerniaghat Foundation (Uttar Pradesh): The Foundation
was established on 17th March 2008. It is contributing to conservation
with the support of U.P. Forest Department and its Katerniaghat
Wildlife Division. They started a project for monitoring vulture
population in collaboration with BNHS (Kat’s Eye, 2009).
Besides India, its neighbours, both Nepal and Pakistan
have recognised the crucial role of breeding centres for the
conservation of vultures and centre have been established in both
countries in the last two years. In Nepal the centre has been
established through a partnership of the Department of National
Parks and Wildlife Conservation (DNPWC), the National Trust for
Nature Conservation (NTNC) and Bird Conservation Nepal (BCN),
with financial support and technical guidance provided by the ZSL
and RSPB. WWF Pakistan with support from The Hawk
Conservancy (UK) has established a breeding centre in Pakistan
(Khan et al., 2008).
Status in Uttar Pradesh
The long-mooted proposal to set up vulture breeding centres
in the state is gathering dust. Kukrail in Lucknow, Katarniaghat in
Bahraich and Chandra Prabha in Chandauli were identified as
prospective places for the centre (The Times of India, New Delhi,
Saturday, January 5, 2008). Vulture species dwelling in Uttar
Pradesh are: Long-billed, Slender-billed, White-backed, King
vulture, Egyptian vulture and Griffon.
Datas from various sources indicate that there are a number
of sites in the state where vultures have been reported to reside.
These include Agra, Etawah, Lakhimpur Kheri (local conservationist),
Natural scavenging vulture, Gyps indicus
November, 2009Research in Environment and Life Sciences 190
Name: Gypaetus barbatus (Lammergeier Or
Bearded vulture)
Description: 125 cm, huge, grey and orange raptor
with long wedge-shaped tail
Distribution: Common breeding reasident in high
northern mountains. Also occurs in S. Europe, Africa
and W. Central and E. Asia
Current status: Uncommon
Name: Gyps bengalensis (Oriental white-backed
vulture)
Description: 85 cm, dark, broad-winged raptor
with large white back patch. Tail is shor
Distribution: Globally threatened. Most frequent
in northern wildlife sanctuaries and now very
scarce in towns
Current status: Critically endangered
Name: Gyps tenuirostris (Slender-billed vulture)Description: 80-95 cm, Thin, rather attenuatedvulture, adults have dark bill with pale culmen;black cere; a near-total lack of feathering on theblack head and neckDistribution: Globally threatened.Restricted toHimachal Pradesh, Haryana, west Bengal,northern OrissaCurrent status: Critically endangered
Name: Gyps himalayensis (Himalayan Griffon)
Description: 125 cm, pale raptor with tail short.
Flight feathers are black
Distribution: Common breeding resident of high
mountains. Also occurs in central Asia
Current status: Uncommon
Name: Aegypius monachus (Cinereous vulture)
Description: 115 cm, huge, chocolate brown
raptor with a blackish face mark. Short, often
wedge-shaped tail
Distribution: Mainly scare winter visitor to
northern mountains and river valleys
Current status: Uncommon, near threatened
Name: Sarogyps calvus (Red-headed vulture or
King vulture)
Description: 85 cm, large, blackish raptor with
red head and neck
Distribution: Scarce but widespread breeding
resident throughout the lowlands
Current status: Uncommon, near threatened
Name: Neophron percnopterus (Egyptian vulture)
Description: 65 cm, medium sized, dirty-white
raptor with a wedge-shaped tail
Distribution: Fairly common breeding resident
throughout region. Also occurs in S. Europe, Africa
and W. Central and E. Asia
Current status: Fairly common
Name: Gyps fulvus (Eurasian Griffon)
Description: 100 cm, huge, rufous-brown, white
head and neck, dark flight feathers and tail
Distribution: Common breeding resident of western
Pakistan and northern India and Nepal. Also occurs
in S Europe, Africa and W. Central and E. Asia
Current status: Uncommon
Name: Gyps indicus (Indian vulture or long-billed)
Description: 90 cm, large,pale brown raptor with
dark flight feathers and short tail
Distribution: Globally threatened. Most frequent
in large wild life sanctuaries
Current status: Critically endangered
Fig. 7: Nine species of vultures found in India [Source: Photographic guide to the birds of India (Grewal et al., 2002)
Kushwaha et al.
November, 2009Research in Environment and Life Sciences 191
Fig. 8: Data of three critically endangered Gyps species (Birdlife Internationa, 2007a,b,c)
Name : Gyps bengalensis
Population estimate : 2,500-9,999
Population Trend : Decreasing
Range estimate (breeding/resident) : 4,917,000 km2
Name : Gyps indicusPopulation estimate : 2,500-9,999
Population Trend : Decreasing
Range estimate (breeding/resident) : 4,917,000 km2
Name : Gyps tenuirostris
Population estimate : 2,500-9,999
Population Trend : Decreasing
Range estimate (breeding/resident) : 1,693,800 km2
Kishenpur sanctuary (Fazlur Rehman, member of assessment
survey), Mahavir Swami Sanctuary, Deogarh in Lalitpur, Jaluan
and Jhansi district. In Deogarh, three species of vultures are residing
at present. These are Sarcogyps calvus (King vulture), Gyps
bengalensis (Oriental white-backed vulture) and Gyps indicus
(L.ong-billed vultures). In Bhagwantpura (District Jhansi) Egyptian
vultures are seen around the slaughter house, however no breeding
site is present (Kushwaha and Kanaujia, 2008, 2009).
Thiry years ago raptor populations in the northern-central
India as a whole and within Delhi in particular appeared to be the
highest in any urban area, world wide (Collar et al., 2001). The
datas of three critically endangered Gyps species (Gyps
bengalensis, Gyps indicus and Gyps tenuirostris) is shown in Fig.
8. Banning of diclofenac and conducting of surveys and research
work is not sufficient to ensure self-sustainability of these populations.
In words of Anil Chhangani captive breeding should not be the only
way to conserve vultures. It is quite certain that a countrywide
rescue programme can save over 100 threatened vultures every
year (Chhangani, 2009). The urgent need is to educate, inform
and involve the localites and children in the plight of rare and
critically endangered species. The involvement of future generation
will surely show positive results.
Natural scavenging vulture, Gyps indicus
November, 2009Research in Environment and Life Sciences 192
References
Ali, S. and Dillon Ripley S.: A Pictorial Guide to the Birds of Indian
Subcontinent. Bombay (1995).
Birdlife International: Species factsheet: Gyps bengalensis (2007a).
Birdlife International : Species factsheet: Gyps indicus (2007b).
Birdlife International: Species factsheet: Gyps tenuirostris (2007c).
Chhangani, A.: Indian forester. pp. 239-251 (2009).
Collar, N.J., Andreev, A.V., Chan S., Crosby, M.J., Subramanya, S. and
Tbias, J.A.: Threatened birds of Asia: The Birdlife International Red
Data Book. Cambridge, U.K. (2001).
Cris ten, Conger: Why is it a bad idea to scare a vulture? http :/ /
animals.howstuffworks.com/birds/vulture-vomit.htm/printable (2009).
Gadhvi, I.R. and Dodia, P.P.: Indian white black vultures Gyps bengalensis
nesting in Mahuva, Bhavnagar district, Gujarat, India. Indian Birds,
Vol.2 No.2 March to April (2006).
Grewal, Bikram, Harvey, B. and Pfister, O. : A Photographic Guide to the
Birds of India (2002).
Houston, D. C.: Family Cathartidae (New World Vultures), In Del Hoyo, J.,
A. Elliott and J. Sargatal, (Eds) Handbook of the Birds of the World.
Vol. 2, Lynx Edicions, Barcelona. pp. 24-41 (1974).
Houston, D.C.: The use of vulture to dispose of human corpses in India and
Tibet. In: P. Olsen and I. Newton (Eds) Birds of Prey. Merehurst
Press. p. 186 (1990).
Houston, D.C. and Cooper, J.E.: The digest ive tract of the whiteback
Grif fon vulture and Its role in disease transmission among wild
ungulates. J. Wildlife Diseases, 11: 303-313 (1975).
Jatayu: Newsletter of the Project; Conservation of Critically Endangered
Gyps species of vulture in India: Newsletter Jatayu, Vol. II (2002-2003).
Kat’s Eye: Katerniaghat Foundation: 1: 13 (2009).
Khan, U., Murn, C. and Farid, F.: Vulture populations in Pakistan and the
Gyps Vulture Restoration Project: Vulture News, 58, 35-43 (2008).
Kushwaha, S. and Kanaujia A.: Submission of Survey Report on Vultures
to U.P. Forest Office (2008).
Kushwaha, S. and Kanaujia A.: Study on present status of vulture (Gyps
spp.) fauna in some regions of Bundelkhand, India. Res. Environ.
Life Sci., 2: 7-10 (2009).
Lawate, W.V.: Lethal Toxicity to Cultures of Veterinary Diclofenac Injection-
IDMA Bulletin (2006).
Markandya, A., Taylor Tim, Longo Alberto, Murty M. N., Murty Sucheta
and Dhavala Kishore: Counting the cost of vulture declines-economic
appraisal of the benefits of the Gyps vulture in India. Environmental
and Resource Economists 3rd World Congress (2006).
Pain, D., Cunningham, A.A., Donald, P.F., Duckworth, J.W., Houston,
D.C., Katzner, T., Parry Jones, J., Poole, C., Prakash, V., Round,
P. and Timmins R.: Causes and effects of temporospatial declines of
Gyps vultures in Asia. Conservation Biology, 17: 661-671 (2003).
Parsi , Khabar: Breeding vultures: The Other Side of the Story, 4th July
(2009).
Prakash, V.: Status of vultures in Keoladeo National Park, Bharatpur,
Rajasthan with special reference to population crash in Gyps species.
Journal of the Bombay Natural History Society, 96: 365-378 (1999).
Prakash, V., Pain, D.J., Cunningham, A.A., Donald, P.F., Prakash, N.,
Verma, A. , Gargi , R. , S ivakumar, S. and Rahmani , A.R. :
Catast rophic col lapse of Ind ian whi te backed vulture, Gyps
bengalensis and long-billed Gyps indicus vulture populations. Biological
Conservation ,109: 381-390 (2003).
Vulture Conservation Project: Nature Surat Club. http://www.natureclub
surat:org/new page-1.htm
Kushwaha et al.