4th EURASIAN CONGRESS ON RAPTORS
COMPILED AND EDITED BY:
ARIZONA STATE UNIVERSITY
JEMIMA PARRY-JONES M.B.E.
THE NATIONAL BIRDS OF PREY CENTRE
The attached reports are from the workshop on declines in Gyps vulture populations, which was held at the 2001 Raptor Conference of the Raptor Research Foundation in Seville, Spain. Earlier workshops on vulture decline had been held in India and in Africa. However, by autumn 2001 a great deal of new research had been initiated, and it was therefore relevant to bring field and veterinary workers together to discuss this issue again. Furthermore, this was the first workshop on vulture decline held at a meeting of the Raptor Research Foundation, and one of our goals was to bring this issue to the attention of a wide audience of raptor biologists. These reports summarize the talks given at the workshop and the discussion which followed.
The presenters in the workshop spoke on topics addressing many components of the vulture decline in Asia. The first two presenters, Vibhu Prakash and Munir Virani, together with their respective co-authors presented papers on the status of vulture populations in India and Pakistan. As Vibhu Prakash indicates, the situation in India is grim, with massive population declines throughout the country. Munir Virani, likewise, documents a less well developed population crash, but one that appears to be headed down the same path as has been observed in India. The next presenters, Andrew Cunningham, Debbie Pain and Lindsay Oaks spoke to the current state of the veterinary investigations into vulture decline. At present, most of the viral and biochemical tests these investigators have conducted have not provided specifics into an actual cause of death and population declines, but they have managed to eliminate a wide range of potential causes. Finally, Vladimir Galushin and Jemima Parry-Jones addressed issues of past vulture populations and current plans on captive breeding programs.
The Long-billed Vulture (Gyps indicus) is considered by some to be comprised of two very distinct species, G. indicus and G. tenuiostris, which differ in many structural features and may not be sister taxa. G. indicus is much closer to other Gyps, while G. tenuirostris has many unusual features. Although we recognize that these two species are likely divergent, in light of the present uncertainty about their status we, the editors, have chosen to retain the current taxonomy in this text, using sub-specific designations where appropriate.
The workshop and these reports were financially supported by Disney's Wildlife Conservation Fund, Disney's Animal Kingdom, the Raptor Research Foundation and the Estación Biológica Doñana. In addition, the last two provided important logistical assistance with the conference. Individuals who assisted in pre-workshop preparations include Scott Tidmus of Disney and Giulia Crema and Miguel Ferrier of RRF. We would also like to thank Denis Bogomolov, Andrew Cunningham, Vladimir Galushin, Lindsay Oaks, Debbie Pain, Vibhu Prakash, and Munir Virani for their participation and willingness to prepare these proceedings. Finally, Keith Bildstein provided important editorial assistance.
We hope that the workshop and these reports will be one step along the road to eventual recovery of Gyps vultures in eastern Asia.
STATUS AND DISTRIBUTION OF VULTURES IN INDIA WITH SPECIAL REFERENCE TO THE POPULATION CRASH IN GYPS SPECIES
Vibhu Prakash, Bombay Natural History Society (BNHS), Hornbill House, Shaheed Bhagat Singh Road, Mumbai, 400023, INDIA, e-mail: email@example.com
Nine species of vultures are recorded from the Indian subcontinent and all are known to be residents (Ali and Ripley 1983). A small population of Cinereous Vulture Aegypius monachus breeds in the country but the majority of the population is migratory. The latter species is seen as far south as Kutch in Gujarat during the winter months. The Bearded Vulture Gypaetus barbatus and Himalayan Griffon Gyps himalayensis are typical mountain species and breed in the upper reaches of Himalayan and Trans-Himalayan regions. The young Himalayan Griffons winter in the Himalayan foothills and sometimes as far south as Kutch in Gujarat (Samant et al. 1995). The Eurasian Griffon Gyps fulvus breeds in the Himalayas but is seen throughout the Indian plains to Deccan plateau during winter. The White-backed Gyps bengalensis, Long-billed Gyps indicus and Egyptian Neophron percnopterus are the most common species of vultures and are known to breed from foothills of Himalayas south till Kanyakumari. The White-backed Vultures are most numerous and are seen in hundreds on large ungulate carcasses over most parts of north, central and east India and up to Karnataka in the south India. The Long-billed is largely a cliff nester and is common at most locations within its distribution except in the southern states of Tamil Nadu and Kerala. The Egyptian Vulture is common over most of its distribution except in northeastern and south India. The King Vulture Sarcogyps calvus which was never very numerous and had its distribution from the foothills of Himalayas to the entire subcontinent, has become quite rare in western and eastern India but is holding on in other parts of its distribution (Samant et al. 1995). Raptor surveys were carried out in various protected areas throughout the country in 1990-93 by the BNHS (Samant et al. 1995). The information on vultures number also was gathered during the surveys.
The major objectives of the study were (1) to determine the present status and distribution of vultures in the country, (2) to determine the major causes of decline in the vulture populations in the country.
Surveys were carried out from April to June 2000 at various locations through out the country where population data on vultures existed from previous studies (Prakash 1988, Grubh R. B. 1989, Samant et. al. 1995). The surveys were carried out in protected areas, outside the protected areas in a radius of 25 km and also along the highways while traveling from one protected area to the other. The road transect method was followed (Fuller and Mosher 1981). Numbers of vultures were also estimated at carcass and garbage dumps. The number of carcasses found while carrying out surveys and the attendant scavengers on them were recorded. The country was divided into five zones for the sake of convenience. The State of U.P., Punjab, Haryana and Himachal Pradesh and parts of eastern Rajasthan were considered in North zones, Western Rajasthan, Gujarat and Maharastra formed the West Zone, Madhya Pradesh was considered in Central zone, Bihar, West Bengal and Orissa wee considered in East Zone and Andhra Pradesh, Karnataka, Tamil Nadu and Kerela in South Zone.
Vulture surveys in different parts of the country
Vulture surveys in various parts of the country were carried out during the months of April and May when vulture populations are the highest, as most of the nestlings fledge during this period. Three teams carried out surveys in different areas.
Population and Distribution
In all, 17 protected areas were covered over a distance of 2718 km. A total of 1396 km was covered along the adjoining areas and 7236 km along the highways. Only Gyps vultures are taken into account, as the population of other species was negligible. The population of other species is dealt with elsewhere.
As the surveys were carried out during summer months, much information could not be obtained on Eurasian Griffon and Himalayan Griffon. The Eurasian Griffon which was regularly seen at Gazipur carcass dump in Delhi and Siliguri Carcass dump in Siliguri were, however, not sighted during the survey probably indicating a decline in population.
A total of 1516 vultures was sighted of which 63% were Long-billed Vultures Gyps bengalensis and 37% Long-billed Vultures Gyps indicus. A total of 62% of the vultures was seen in protected areas, 11% in areas around protected areas and 27% along highways.
The abundance of Long-billed Vultures was highest in protected areas at one vulture per 5.2 km, followed by adjoining areas (one vulture per 13.6 km) and along highways (one vulture per 22.2 km).
The abundance of Long-billed was also highest in protected areas at one vulture per 6.48 km, followed by areas adjoining protected areas, one vulture in 21.47 km and along highways, one vulture per 91.59 km.
Neck drooping behavior such as seen in White-backed and Long-billed Vultures at Keoladeo National Park was observed in different parts of the country. In Keoladeo National Park (Prakash 1999) the birds were usually found dead on the nest, on trees or on the ground below the trees. Several deaths were observed. Prior to death, individual vultures were seen perched on trees, dozing, with the neck slowly limping down and would wake up with a start, as the beak hit the branch. The bird usually remained in this condition for more than 30 days (n=5) and then would fall off the branch, sometimes getting caught in the branches of the trees and at times falling on the ground. The birds would die within minutes of falling. We likely only observed a small proportion of the total number of dead vultures.
The adult to juvenile ratio recorded for Long-billed Vultures was 9:1, which probably suggests breeding failure in the species, as they raise only one chick every year and generally have high breeding success.
Nest Habitat Availability
Although no systematic study of the availability of nest habitat was carried out, it was clear from visual observations that sufficient nest habitat was available, and abundant, because of the presence of good number of tall trees. A number of tall Ficus spp, Azadaritica indica, Dalbergia sisso, Acacia nilotica and Sygizium cumini were seen besides a few other tall species in most of the areas. Most of the trees did not have vulture nests. In the desert part of the west zone, traditionally there are few tall trees, but the few available trees were also not occupied.
Nest site availability was determined in Keoladeo National Park based on the data on tree use for nesting and it was found that there were more than 4000 potential sites available but none were utilized for nesting.
Information on food
availability was obtained by counting carcasses seen while carrying out vulture
surveys. It is quite likely that a
number of carcasses w
here missed because the counts were carried out
only along the roads. So, the road counts represent the minimum number of
carcasses available. Dog carcasses were not taken into account.
A total of 192 carcasses was recorded during the survey and only 5 % of the carcasses had vultures feeding on them. In and around Desert National Park, 100 carcasses were seen but only 4 % of the carcasses were attended by vultures. Extremely dry conditions prevailed in Rajasthan and Gujarat and large number of cattle perished. Hundreds of carcasses were seen unattended by vultures at Bapne carcass processing plant, near Mumbai, Tonk carcass processing plant on Jaipur- Tonk road, and Gazipur carcass dump, Delhi. No vultures were sighted at Hapur carcasses processing and bone collection center. These places were full of vultures a decade ago.
The availability of cattle
carcasses in a month was estimated in Bharatpur district. The information was
largely collected from hide collectors. It was estimated that in the district,
2500 cattle carcasses are reported every month, of which 80% are of young
animals and 20% of adults. Assuming that the average weight of a carcass would
be 100 kg, 2
,50,000 kg of carcass will be available in a month. About
50,000 kg could be taken as waste composed primarily of hides and skeletons.
About 200,000 kg of meat will be available for the scavengers. This quantity of
meat would be able to support 13,000 vultures for a month assuming that a
vulture consumes not more than 500 gm a day.
So, the food appears to be available in abundance.
Population estimation of vultures in various carcass dumps
Vulture populations were estimated at carcass dumps in different zones. The dumps are Hapur, Gazipur and Chatta in north zones, Siliguri in east zone, Bapne in west Zone. Gyps species were sighted only at Siliguri and Gazipur but in much reduced numbers. We observed population declines of more than 90% at all the dumps.
The population of both White-backed and Long-billed Vultures has crashed all over the country. The decline in population is more than 90% in all the areas surveyed. The population of vultures have declined in protected areas as well as rural areas to almost the same extent, but remnant populations were seen in some protected areas. In some areas vultures have been completely extirpated.
The major causes of the population decline appear to be high mortality and total breeding failure as has been recorded in Keoladeo National Park (Prakash 1999) and as indicated by low adult juvenile ratio recorded in different parts of the country.
Food appears to be abundant, as only 4% of the cattle carcasses recorded had vultures feeding on it. Food availability estimated in Bharatpur district of Rajasthan revealed enough food for about 13,000 vultures in this district alone but only 200 vultures were estimated through out the district. So it was clear that paucity of food was not a cause of decline in the population of Gyps species of vultures.
The nesting and roosting habitats also were found to be in abundance all over the country. The nesting habitat availability estimated at Keoladeo National Park revealed 4,000 potential nesting sites but there was no nest in the Park. So, it was evident that there was no paucity of habitat which could have caused a decline in vulture population.
The neck drooping syndrome as seen in sick vultures was noticed throughout the country in both the species. A number of dead vultures were seen in Keoladeo National Park. Total breeding failure was recorded in the population of White-backed Vultures since 1997 (Prakash 1999). The low proportion of first year birds does indicate breeding failure. So high mortality and total breeding failure appears to be the major cause of population decline.
The birds appear sick and lethargic as they sit with limp necks, and die within 30-32 days, it appears disease to be the cause of mortality and breeding failure. The symptoms of disease have been recorded only in Gyps vultures, which may indicate a viral disease as viruses are known to be genus-specific.
There is a real danger of both White-backed and Long-billed Vultures, which are long living and slow breeding large species, becoming extinct because of breeding failure and high mortality.
Future plans of Studies on Vultures in India
1. Monitor the nesting sites of both species of vultures
2. Collect dead vultures from different regions of the country for pathological and toxicological examination.
3. Develop a multidisciplinary team of biologists, pathologists and toxicologists for systematic investigation of the agents killing the vultures.
4. Establish a center to keep vultures in captivity for observations and experimentation for detection of disease and for trial of drugs and also for captive breeding.
Ali, S. and Ripley, S. D. 1983: Handbook of Birds of India and Pakistan, Compact Edition. Oxford University Press New Delhi.
Fuller M. R. and Mosher J. A. 1981. Methods of detecting and counting raptors: A review. In Estimating Number of Terrestrial Birds, Eds. Raph J.N and Scott J. M.Studies in Avian Biology No. 6: 235-246. Cooper Ornithological Society.
Grubh R. B. 1989: The ecology and behaviour of vultures in Gir forest Ph. D. Thesis. University of Bombay, Bombay.
Prakash, V. 1999. The Status and Distribution of Vultures in Keoladeo National Park, Bharatpur, Rajasthan, with special reference to the crash in population of Gyps species.
Prakash, V. 1988: The General Ecology of Raptors (Families: Accipitridae, strigidae, Class: Aves) in Keoladeo National Park, Bharatpur, Unpublished Ph. D. thesis, Department of Field Ornithology, Bombay Natural History Society, Bombay University, Bombay.
Samant J. S., Prakash, V. P., and Naoroji, R. 1995. Ecology and Behaviour of Resident Raptors with Special Reference to Endangered Species. Final Report 1990-1993, Bombay Natural History Society, Mumbai.
ASIAN VULTURE CRISIS PROJECT: FIELD RESULTS FROM PAKISTAN AND NEPAL FOR THE 2000-2001 FIELD SEASON
Munir Virani, Martin Gilbert, Rick Watson, The Peregrine Fund, 566 West Flying Hawk Lane, Boise Idaho, 83709 USA, e-mail: firstname.lastname@example.org ; Lindsay Oaks, Dept. of Veterinary Microbiology and Pathology, Washington State University, Pullman Washington 99164-7040 USA; Patrick Benson, University of Witswatersrand, South Africa; Aleem Ahmed Khan, Ornithological Society of Pakistan, 109/D P.O Box 73, D.G. Khan, Pakistan; Hem Sagar Baral, Jeet B. Giri, Bird Conservation Nepal P.O Box 12465, Kathmandu, Nepal.
Since 1997, Prakash (1999) has highlighted the collapse of populations of two species of Gyps vultures in Keoladeo National Park, India. Subsequent surveys show that the significant numerical declines of Gyps vultures of at least three species is mirrored all over India (Prakash and Rahmani 2000). Noticeable with the decline in vultures was an unusual and previously unnoticed head drooping behavior, considered to be a clinical sign of sick birds (Prakash and Rahmani 2000). Large-scale vulture deaths also were reported during the summer months (Riseborough et al., in prep; MV pers. obs.; various interviews with villagers in West Bengal, India and Punjab Province, Pakistan), while a large proportion of freshly necropsied vultures died of renal failure (visible as visceral gout or the deposition of uric acid crystals in the viscera) (Cunningham 2000). The combination of a widespread Gyps population collapse, previously unobserved head drooping, extensive mortalities in summer months and renal failure in the majority of necropsied vultures represented a condition that was apparently unusual but specific to Gyps vultures. Two factors were initially hypothesized as being responsible for the deaths and subsequent declines of Gyps vultures – (1) a disease (Riseborough et al., in prep; Cunningham 2000; Prakash and Rahmani 2000), and (2) contamination as a result of excessive pesticide use (mainly insecticide based) (e.g. Nair 1999). Whatever the cause of decline, Gyps species (mainly G. bengalensis, G. indicus indicus and G. i. tenuirostris) are at high risk. A disease has the potential to affect contiguous populations of Gyps vultures occurring in Europe and Africa while indiscriminate pesticide use could depress existing populations to unviable levels throughout the Indian subcontinent.
The Asian Vulture Crisis Project
In October 2000, The Peregrine Fund along with its partners commenced intensive field-based ecological and diagnostic studies in Pakistan and Nepal and supported ongoing field studies in India. Our aim was to understand the causes of vulture declines specifically with respect to renal failure and mortality in South Asia. Our objectives were to:
(1) measure mortality of Gyps vultures of each age-class and identify temporal, spatial and other patterns in mortality that would help reveal the underlying cause of renal failure in these birds;
(2) identify the causes of death wherever possible through necropsy and diagnostic evaluation of tissue samples; and
(3) measure breeding productivity and understand other behavior that might affect vulture population dynamics.
The bulk of our efforts were focused on the Punjab Province of Pakistan where we intensively monitored populations of White-backed Vultures (G. bengalensis) at two main sites (Dholewalla and Changa Manga). We also intermittently monitored vultures at 15 other peripheral sites. In Nepal, we conducted our field studies in and around the periphery of Koshi Tappu Wildlife Reserve. Our field studies involved locating and daily monitoring vulture nests in our study areas. We counted nests, recorded nest occupancy, breeding status, breeding behavior, occurrence of head drooping, collected dead vultures from the areas near nests, and conducted necropsies and tissue collection for diagnostic analyses on all freshly dead vultures.
We found 3697 White-backed Vulture nests in the Punjab Province of Pakistan. We estimated breeding success to be approximately 0.4 chicks per active nest from a sub-sample of 418 nests. We found and collected 676 dead vultures during the study period from December 2000 to July 2001. We estimated a mean adult annual mortality of 16%, while fledgling mortality was estimated at 50% in the four-week period immediately after fledging. Adult and sub-adult mortality was consistently high during the study period while nestling mortality was low until April and May when it increased due to fledgling fatalities, we believe attributed to naivete (e.g. unable to take off after their first flight). We necropsied a total of 183 White-backed Vultures. Out of 69 adult and sub-adult vultures necropsied, 71% had gout and the rest died of trauma, collision, lead poisoning and various other causes. A small proportion (18.4%) of the 114 fledglings and nestlings necropsied had gout while the rest died from dehydration, heat stress, injury and other causes presumed to relate to the naivete of birds during the post fledging period. We found a strong positive correlation between the proportion of head drooping vultures and increasing ambient temperatures. Ongoing diagnostic work for disease, toxins, and nutritional deficiency has not, so far, revealed any consistent underlying cause of renal failure.
At our study area in Nepal, we found 67 vulture nests (65 White-backed and 2 Slender-billed) of which 27 (40%) were active during the study and only 19 (28.4%) successfully fledged young birds. We found and collected 45 dead White-backed Vultures during the study period of which 34 (75.5%) were adults. We necropsied three freshly dead White-backed Vultures (2 adults and a nestling) and found gout in both the adults. We also conducted a survey of 23 agro-chemical shops in the Koshi area. Phorate, Malathion (both organophosphate compounds) and Fenvalerate (a synthetic pyrethroid) were the most popular selling brands of pesticides in the area. Sales of the two organophoshate pesticides have increased by 7 and 4-fold respectively whilst that of Fenvalerate has increased 16-fold over the last 5 years.
The results of our first year have shown that while there is still a large population of White-backed Vultures in the Punjab province of Pakistan (compared to India and Nepal), there is high adult mortality indicative of a rapidly declining population. The presence of visceral gout in 71% of adult vultures necropsied in Pakistan signifies that vultures are likely to be dying of the same cause that has extirpated vultures in India.
The fact that nestlings and fledglings were affected by gout indicates that the cause may be transmitted from adults to progeny at the nest. This could be in the form of food brought back to the nest, or may be inherently present at nest sites. The lower proportion of nestlings and fledglings affected by gout does not necessarily mean that adult and sub-adult vultures are more vulnerable to the mortality factor than younger birds because the rate of fledging mortality due to naivete is very high and unique to this age-class. Proportional death rates are therefore not comparable.
Mass vulture deaths reported during the summer in parts of India and Pakistan are more likely the result of fledgling deaths that occur naturally soon after the fledging period which coincides with the hot months of April and May. This period also coincides with a peak in “head-drooping” behavior, which our results suggest was a previously overlooked behavioral response to increasing ambient temperature and possibly other stresses. Thus, all head drooping vultures are not necessarily sick but sick vultures may droop their heads.
Breeding success of about 0.4 chicks per active nest is in the range measured for other Gyps vulture species in Africa, may be normal, and suggests that breeding failure is not behind the species’ population decline. Thus, organochlorine pesticides that cause egg-shell thinning are not implicated.
The proximate cause of renal failure in White-backed Vultures still remains unknown. The fact that adult and sub-adult mortality in this species is unusually high and indicative of a declining population is unequivocal. There are still large gaps in our knowledge. Questions about the status, rate and extent of mortalities, and breeding success of other Gyps vultures such as the Long-billed Vulture need to be answered alongside diagnostic work. Declines in other raptors, extent of pesticide use and changes in livestock management practices in vulture habitats also warrant more careful study than has been achieved so far. While recognizing that recent political global events may impede our conservation efforts, we will continue to work alongside our partners in South Asia to achieve our goals.
Funding for this project was received from the Gordon and Betty Moore Foundation, UN Foundation, Disney Company Foundation Conservation Awards, and the Zoological Society of San Diego. We would like to thank the following organizations for their partnership, help and co-operation: in Pakistan, the Ornithological Society of Pakistan (OSP), Punjab Department of Wildlife and Parks, Lahore Zoo, National Council for the Conservation of Wildlife (NCCW), B.Z. Multan University, University of Agriculture at Faisalabad, Sind Wildlife Management Board, Zoological Survey Department Pakistan and Pakistan Museum of Natural History; in Nepal, Bird Conservation Nepal (BCN) Himalayan Nature, Koshi Camp, and Department of National Parks and Wildlife Conservation (DNPWC). In the USA, The Zoological Society of San Diego, Washington State University and the Bodega Bay Institute. Last but not least, all the dedicated field research staff who worked tirelessly to collect data under demanding conditions.
Cunningham, A. 2000. Investigation of vulture mortality in India. Report of a visit to India (February-March 2000) RSPB and BNHS.
Nair, A. 1999. What’s Eating the Vultures? Down to Earth. 15th January 1999 issue pp 29-39. Nair A [ed.] with inputs provided by Asad Rahmani of BNHS; Padma S Vankar of IIT Kanpur; Karim Ahmed of World Resources Institute, Washington, DC, Ranjita Biswas, Calcutta and Kazimuddin Ahmed, Priti Kumar, Amit Nair, Manish Tiwari, and N Venugopalan, of CSE. Copy written by Arnab Ray Ghatak.
Prakash, V. 1999. 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.
Prakash V & Rahmani, A. 2000. A brief report on the international seminar on vulture situation in India. BNHS, New Delhi 18th to 20th September 2000.
INVESTIGATING THE CAUSE OF CATASTROPHIC DECLINES IN ASIAN GRIFFON VULTURES, GYPS INDICUS AND G. BENGALENSIS
Andrew A. Cunningham, Institute of Zoology (IoZ), Zoological Society of London, Regent's Park, London NW1 4RY, UK, e-mail: Andrew.Cunningham@ioz.ac.uk , Vibhu Prakash, Bombay Natural History Society (BNHS), Hornbill House, Shaheed Bhagat Singh Road, Mumbai, 400023, INDIA, G.R. Ghalsasi, Poultry Diagnostic and Research Centre (PDRC), Venkateshwara Hatcheries Limited, Pune, INDIA, Deborah Pain, Royal Society for the Protection of Birds (RSPB), The Lodge, Sandy, Bedfordshire SG10 2DL, UNITED KINGDOM.
Populations of two of India’s commonest griffon vultures (genus Gyps) have declined by >90% during the last decade. Both affected species, the White-backed and Long-billed Vultures (Gyps bengalensis and G. indicus), were once regarded as very common in India, but now they are listed as critically endangered by the IUCN.
The problem was originally highlighted by Dr Vibhu Prakash, principal scientist of the Bombay Natural History Society (BNHS). His initial findings at Bharatpur showed a 96% decline in numbers of Long-billed Vulture and a 97% decline in Long-billed Vultures between 1985 and 1999 (Prakash 1999). Similar results have now been shown for these species throughout India following a nation-wide survey (Prakash, these proceedings). Prakash (1999) noticed that vultures appear lethargic and sick with drooping heads for several weeks before death. This abnormal behavior, along with dead vultures, was also found throughout the country.
Since late 1999, the RSPB has been working closely with BNHS on this problem. This has included the provision of assistance to help identify the extent of the decline and its causes. The RSPB contracted the Institute of Zoology (IoZ) to help with these investigations, and this has involved visits to India to assess the problem and advise on necessary actions to elucidate its cause.
From the work of Prakash (1999), it was clear that the vulture declines are due to exceptionally high mortality of vultures, with all age classes being affected. Also, the reproductive rate is abnormally low. This is probably due to direct and indirect effects of the high mortality.
The pattern of vulture mortality (apparently confined to Gyps spp. with sympatric scavengers of other genera being unaffected; the spatial and temporal extent of the high mortality) strongly indicates that an infectious disease process might be involved. In order to investigate this further, however, reasonably fresh carcases of affected vultures are required for detailed post mortem examination and follow-up diagnostic tests. Obtaining such carcases has not been an easy affair, and a large number of people have spent a great deal of time occupied with this aspect of the work. To date, we have examined in detail approximately 30 carcases, comprising both Long-billed and White-backed, adults and juveniles.
Many of the birds found dead have evidence of enteritis and of severe renal and visceral gout. Although renal gout is often attributed to kidney disease, in these cases the gout has been extensive and acute (or peracute) – i.e. occurring only a few hours (or less) before death. This condition is, therefore, a consequence of the primary disease and not the disease itself. It is most likely a response to terminal dehydration of the affected bird, although this has not yet been proved. The affected carcases examined so far have been in varying states of nutritional fitness, with some of the birds having substantial amounts of body fat. This is probably an indicator of the period of time which has elapsed between an individual bird becoming sick and its death – a time which is likely to have a degree of variance.
Apart from the gout and enteritis, there has been remarkably little to see at gross post-mortem examination of affected vultures. This is true also for the histopathological studies (whereby tissues are examined at the cellular level using light microscopy). One finding of note, however, is that most of the birds examined so far have varying degrees of perivascular lymphocytic cuffing (a finding first noticed on the first vulture examined by one of the authors (AAC) in February 2000). This is a reaction usually seen in cases of infectious disease, and one that is most commonly associated with infection with a viral agent. Although these findings are tantalizing, they do not yet provide an answer as to the cause of the disease killing the vultures. Work is on-going both (1) specifically aimed at identifying a viral cause of the disease, as suggested by the diagnostic investigation so far, and (2) broadly aimed at identifying any possible cause of the birds’ demise – infectious or non-infectious. We are keeping our diagnostic minds as open as possible because, although our findings indicate viral involvement, this may not be the case or, if so, it may only be part of the story.
Although, the declines are only apparent in White-backed and Long-billed Vultures, there are insufficient data to judge population changes in other species. However, Prakash has recently reported small numbers of seemingly sick (exhibiting neck-drooping) and dead Eurasian Griffons Gyps fulvus and Himalayan Griffons Gyps himalayensis in Rajasthan, India. These species are migratory, wintering in India.
The international implications of this problem are very concerning. As an infectious disease appears to be affecting two species of griffon vulture (White-backed and Long-billed), it is conceivable that it will spread to other griffon species, and both the migratory Himalayan and Eurasian Griffons may already have been exposed. The ranges of species of the Gyps genus overlap from India through central Asia and the Middle East to South Africa and Western Europe. Gyps species are known to travel widely and it is conceivable that a disease that affects all Gyps spp. vultures could spread from South Asia throughout the old world. All BirdLife Partners in Gyps spp. range states have been made aware of the problem and encouraged to monitor vultures in their areas. In May 2000 a workshop was run in Kenya to plan vulture monitoring and Conservation (Bennun & Virani 2001).
The dramatic vulture declines observed across India present a whole range of threats, both ecologically and to human health. The absence of such important scavengers will almost certainly influence the numbers and distribution of other scavenging species. For example, as vultures have declined feral dog populations have been reported to have increased massively, with over 1,000 observed recently at a carcase dump in Rajasthan - this could pose many associated disease risks to humans and wildlife, such as rabies.
In October 2000, we jointly applied for a grant from the UK government under the ‘Darwin Initiative for the Survival of Species’ to fund the urgent vulture investigations. We were successful in our bid and from 1st April 2001, the Darwin Initiative is providing funding for a 3 year project investigating causes of the dramatic declines in Gyps spp. griffon vultures in India.
The Darwin project partners are the IoZ, RSPB and NBPC in the UK, and BNHS and PDRC in India. The aims of the Darwin project are to:
(1) Identify the cause of the declines and potential remedial measures.
(2) Establish a captive care facility for sick and potentially healthy vultures.
(3) Conduct annual nationwide monitoring of vulture numbers and produce a monitoring strategy.
(4) Produce a recovery plan.
In addition to the work within India, Dr Alex Hyatt and others from the Australian Animal Health Laboratory (CSIRO), one of the foremost laboratories in the world dealing with the identification of existing and novel pathogens in wildlife, are also collaborating with this work.
Prakash, V. J.,1999. Status of vultures in Keoladeo National Park, Bharatpur, Rajasthan, with special reference to population crash in Gyps species. J. Bombay Nat. Hist. Soc. 96(3): 365-378.
Bennun, L. & Virani, M. 2001. (eds). Responding to the Asian vulture crisis: Planning for vulture monitoring and conservation in Kenya. Proceedings and recommendations of a seminar and workshop held at the National Museums of Kenya, 10 May 2001. NMK Ornithology Research Report 41: June 2001.
SUMMARY OF DIAGNOSTIC INVESTIGATION INTO VULTURE MORTALITY: PUNJAB PROVINCE, PAKISTAN, 2000-2001
J. Lindsay Oaks, Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164-7040, USA, e-mail: email@example.com , Bruce A. Rideout, Center for Reproduction of Endangered Species, Zoological Society of San Diego, PO Box 120551, San Diego, CA 92112-0551, USA; Martin Gilbert, Rick Watson, Munir Virani, The Peregrine Fund, 566 West Flying Hawk Lane, Boise, ID 83709, USA; and Aleem Ahmed Khan, Ornithology Society of Pakistan, 109/D PO Box 73, Dera Ghazi Khan, PAKISTAN.
The veterinary diagnostic investigation into the causes of death of White-Backed Vultures (Gyps bengalensis) in Pakistan was initiated in November, 2000. Data from field studies have indicated overall mortality in adult vultures of 8-15% per year, a rate predicted to result in a population decline. Gross post mortem examinations have been performed on a total of 69 adult vultures, 49 (71%) of which had evidence of renal failure (visceral gout, with classic gross lesions of uric acid deposits on heart, pericardium, liver, kidneys). More detailed necropsies were performed on 36 of these vultures, and the cause of death was either apparent on initial necropsy and/or samples were collected for diagnostic testing. Among the 27 adults and sub-adults in this group, 21 (78%) had gross evidence of renal failure. These 27 birds were further characterized as being in good physical condition (normal pectoral muscles, adequate body fat), and did not have an apparent reason for renal failure. Gout was present in only one of the 9 (11%) immature, fledgling, and neonatal vultures examined. Significant mortality in other birds or mammals, including other scavengers, was not noted. These data suggest that there is a disease selectively affecting the kidneys (directly or indirectly) of adult and subadult vultures resulting in sudden death. Additional testing was undertaken to determine the cause of renal failure/death in these vultures, with a case being defined as an adult or subadult vulture in good physical condition and with visceral gout. No vultures with gout have been observed alive, and thus clinical disease observations have not yet been incorporated into the case definition.
Of the 36 vultures necropsied in detail, 23 (10 with gout, 13 without gout) were in adequate post mortem condition for additional testing; the remaining 13 cases were in advanced states of decomposition and unsuitable for analysis. The 13 cases without gout included most of the fledgling and nestling vultures, and a cause of death was determined for all but one of these cases and include trauma, gunshot, and lead poisoning. There was no evidence that underlying disease was a factor in these cases, and these deaths are assumed to be miscellaneous and not a threat to the population. Remaining diagnostic efforts have focused on the 10 gout cases suitable for testing. In only one of these cases has an underlying disease been identified (avian tuberculosis).
Testing performed to date includes histopathology, virology, electron microscopy, bacteriology, and toxicology. The most significant histopathologic lesions are those of avian visceral gout. Lesions compatible with a primary infectious disease of the kidneys or other organs were not consistently apparent. Various other lesions were noted (e.g. enteritis, meningitis, arteriolitis, tracheitis), but these were not present consistently in all the birds suggesting that none of these lesions are indicative of a common underlying disease. Also, oxalate crystals in the kidneys indicating ethylene glycol toxicity were not observed. A key distinction that remains to be confirmed is whether the renal lesions are due to primary or secondary renal disease (dehydration), but autolysis and the severity of the lesions has made this assessment difficult.
Microbiology results were mostly negative, consistent with the absence of significant inflammatory lesions. Virus isolation using at least 4 passages on chicken embryo fibroblasts, duck embryo fibroblasts, and peregrine embryo fibroblasts has detected a single cytopathic agent from the lung/spleen from one vulture. Lung, spleen, kidneys, and intestine from all other vultures tested were negative. Efforts are currently underway to identify this virus and evaluate its significance. Negative stain electron microscopy on intestinal contents did not detect viruses or other potential disease agents. Bacteriology has not identified any obligate pathogens or opportunistic pathogens in a pattern consistent with disease.
Toxicology has been pursued extensively because the acute nature of the deaths and absence of significant renal inflammation is most consistent with poisoning. Although organochlorine pesticides (lindane, dieldrin, DDD, DDE, and DDT) have been detected in fat, indicating exposure to these pesticides, the levels of organochlorine pesticides in brain or liver are all well below the levels associated with acute intoxication. No organophosphates (OP’s), OP metabolites, or carbamates were detected in brain or liver. OP and carbamate poisoning was further evaluated by measuring brain acetylcholinesterase (ACE) levels. Although data for normal brain ACE levels in Gyps spp. is limited, the mean ACE level for gout birds was similar to the mean ACE levels for the non-gout birds and known normal vultures. Heavy metal concentrations in tissues were analyzed for toxic and deficient levels. Lead poisoning was identified in one non-gout vulture. Toxic levels of arsenic, cadmium, copper, iron, manganese, molybdenum, lead, mercury, and zinc were not detected in any other birds. The levels of copper and molybdenum may be deficient in some individuals, but a clear pattern of deficiency does not distinguish the gout from the non-gout birds.
The testing performed to date has not identified a common, underlying cause of renal disease or visceral gout in these vultures. Although the role of an infectious disease cannot yet be completely ruled out, and is currently still under investigation, the negative histopathology and microbiology results strongly suggest that other causes need to be considered. The possibility of the avicide 3-chloro-p-toluidine, a toxin that specifically targets the avian kidney and results in visceral gout, has been mentioned frequently. However, this poisoning is very unlikely to be associated with the vulture deaths for the following reasons: first, avicide is not known to be used in Pakistan; second, it does not have any other known use; third, raptors are generally quite resistant in experimental exposures; and, fourth, by the time a poisoned bird dies the active ingredient is completely metabolized (United States Environmental Protection Agency Reregistration Eligibility Decision: Starlicide (3‑chloro‑p‑toluidine hydrochloride),1995). Thus, secondary poisoning of vultures would be extremely unlikely. Field studies are ongoing in Pakistan to further identify potential environmental contaminants, and to continue to collect diagnostic material for analysis.
POPULATIONS OF VULTURES AND OTHER RAPTORS IN DELHI AND NEIGHBORING AREAS FROM 1970's TO 1990's.
V.M.Galushin, Russian Bird Conservation Union, 60 Shosse Enthuziastov, Moscow, 111123, Russia, e-mail: firstname.lastname@example.org
The vulture tragedy in India has raised many urgent problems including a search for the very causes of that phenomenon as well as measuring its actual degree. Studies by Dr.Vibhu Prakash (1989, 1999; Prakash and Rahmani, 2000) showed the great decline (over 90%) of the White-backed Vulture within Keoladeo National Park in 1990s. Many other studies on the matter indicated decline or crash of vulture populations at the end of the 20th century (Rahmani, 1998; Satheesan, 2000a, 2000b; Thiollay, 2000; Watson, 2000; Threatened Birds of the World, 2000; Threatened Birds in Asia: the BirdLife International Red Data Book, 2001). At the same time there are some other areas for comparative study of changes in populations of Vultures and other raptors based on their special surveys in Northern-Central India in 1967-1971, 1984-1986 and 1996.
MATERIALS AND METHODS
Working as a UNESCO expert in biology education in Delhi from September 1967 till December 1971 the author used his week-ends and other free hours for survey of raptors within Delhi and in agricultural areas 30-70 km away. After assignment in India the author made some surveys in Delhi during four short (2-8 days) visits to the country in 1984-86. The last survey also in Delhi was done together with Mrs. Nataly Zakharova-Kubareva in February 1996.
Outside Delhi three sample areas were surveyed mostly in the 1969-70 breeding season (December-May). They were the Rothak (20 sq.km), Pataudi (20 sq.km) and Baghpat (10 sq.km) areas. Each area consisted mainly of cultivated fields with wheat, maize, sugar cane, etc. 10 to 20% of each area was not cultivated (grasslands, bushes, sand dunes, and alike). They also were covered with scarce babul (Acacia), banyan (Ficus), nim (Melia) and some other trees. 2-5 villages were situated within each sample area.
In Delhi (150 sq.km at that time) raptors were surveyed during September-May of four seasons: 1967-68, 1968-69, 1969-70, and 1970-71. 26 sample areas were selected there: 9 within a central north-south strip (850 m x 17,000 m) as well as 17 additional samples of various sizes (15 – 510 ha each) west and east of the central strip. In total the sample areas occupied 37 sq.km (about 25% of the entire city area at that time). During short visits in 1980's and 1996, from 3 to 7 of the above areas were surveyed.
Survey methodology was simple but reliable. Every sample area was thoroughly searched from tree to tree for occupied nests (c.80% of all records) and birds with obviously breeding behavior (nesting areas comprised about 20% of total registrations). One agricultural sample area (10-20 sq.km) took 3-4 full day visits while each sample area in Delhi (50-500 ha) also required at least 2-4 visits to count every raptor nest. All active raptor nests and nesting areas were mapped on large scale maps (from 1 cm per 200 m in Delhi to 1 inch per 1 mile outside it). All those original maps and detailed descriptions (in Russian) of each nest and nesting areas are kept with the author and available for further studies.
The above surveys allowed assessment of the populations of raptor species both in Delhi and outside it. Some results for 1967-71 have been published (V.M.Galushin 1969, 1971, 1974, 1980, 1985, 1992, 1996). Results of a joint survey was presented at the Salim Ali Seminar in Bombay, India, and published there (Galushin and Zakharova-Kubareva, 1998). Summarized data of the raptor surveys from 1970s to 1990s are given below.
Pataudi area (20 km2) in Gurgaon District, Punjab, 40 km south-west of Delhi included 5 villages (Tatarpur, Baslanbhi, Ghausgarh and others) and over 1800 trees of babul (Acacia arabica), banyan (Ficus bengalensis), nim (Melia indica) and others with some 200 trees of 10 meters or higher (mostly in or near villages). 27 pairs of raptors were mapped: 19 pairs of White-backed Vultures (Gyps bengalensis), 4 pairs of Egyptian Vultures (Neophron percnopterus), 3 pairs of Black Kites (Milvus migrans); and one likely nesting Laggar Falcon (Falco jugger) was also noted. Half of the nests were in villages or within 200 m of villages. Total average density was 13.5 pairs per 10 km2.
Rohtak area (20 km2) also in Punjab but 70 km north-west of Delhi included three villages (Lahli was the largest), a wide canal which crossed the area from north to south and over 5000 trees with about 1200 ones above 10 m in height. 53 raptor pairs were counted: 36 pairs of White-backed and 4 pairs of Egyptian Vultures, 5 pairs of Black Kites, 3 pairs of White-eyed Buzzards (Butastur teesa), 2 pairs of Black-shouldered Kites (Elanus caeruleus), 2 pairs of Tawny Eagles (Aquila rapax), and one pair of Crested Honey Buzzard (Pernis ptilorhynchus). A density was 26.5 pairs per 10 km2.
Baghpat area (10 sq.km) in Meerut District, Uttar-Pradesh, 30 km north of Delhi included 2 small villages (Rasulpur and Basa Tikri), a large canal crossed the area from north to south with high trees along it and over 3600 trees, about 900 of them higher than 10 m. 32 pairs of raptors were counted: 15 pairs of White-backed Vultures (mostly along the canal), 4 pairs of Black Kites, 4 pairs of Egyptian Vultures, 3 pairs of Black-shouldered Kites, 2 pairs of White-eyed Buzzards, one pair of Tawny Eagle. Beside them probably two pairs of Crested Serpent-Eagles (Spilornis cheela) and one pair of Greater Spotted Eagles (Aquila clanga) have been noted but their nesting was not confirmed. Density of nesting raptors was highest there at 32 pairs per 10 km2.
Within the three agricultural sample areas monitored (50 km2 altogether), 112 pairs of 10 species of nesting birds of prey were recorded. Average density was 22.4 pair per 10 sq.km. The most numerous species were White-backed Vultures (70 pairs with a density of 14 pairs per 10 km2) which comprised over 62% of all birds of prey. Black Kites (12 pairs) and Egyptian Vulture (also 12 pairs) comprised about 20% of the total number of raptors. 7 others of the above species could be considered as uncommon or rare in agricultural areas of Northern-Central India. Human settlements comprised a small part of the agricultural sample areas (not more than 5% altogether) while over 30% of all birds of prey (mostly Vultures and Kites) nested within or nearby villages where they presumably found both food to eat and high trees in which to nest. It is also important that local people were very tolerant to wild birds including raptors and never disturbed them.
Much more numerous populations of birds of prey were found in large cities. Within Delhi (about 150 km2 at that time) six raptor species were recorded: four nesting ones (White-backed and Egyptian Vultures, Black Kite and Shikra, Accipiter badius) and two probably nesting (Crested Honey Buzzard and Black-winged Kite). That is slightly less than 8 nesting species noted by Usha Ganguli (1975) and half the 11 mentioned by Hutson (1954) and the 13 species (including 6 reliable nesters) in the recent list by Vyas (1996).
The average density of urban raptors in 1968-1970 was 193 pairs per 10 km2; with Black Kite (161 pairs per 10 km2), White-backed Vultures (27 pairs per 10 km2), and Egyptian Vultures (5 pairs per 10 km2) as apparent dominants. Extrapolating, it seems reasonable to estimate that in 1970 Delhi was inhabited by about 3000 breeding pairs of raptors. Out of them at least 2400 pairs were Black Kites and 400 pairs of White-backed Vultures (Galushin, 1969, 1971). Similar numbers for those times were indicated by Ali and Grubh (1984) and Malhotra (1996). However surveys of some sample areas in Delhi in 1984-1986 showed that a population of Kites decreased on about 25-30% while a number of Vultures increased at least twice. They appeared in the greatest number in central and southern areas of Delhi where they had been totally absent at the beginning of 1970's. Nevertheless in February 1996 the number of Vultures declined 25-30% and Kites continued their slight decline (on 10-20%) (Galushin and Zakharova-Kubareva, 1998). For example, within three green sample areas Chanakyapury, Jor-Bagh and Lodi Park (together 420 ha) considerable changes were noted: 1970 – 37 pairs of Kites and no Vultures, 1986 – 23 pairs of Kites and 45 pairs of Vultures, 1996 – 18 pairs of Kites and 29 pairs of Vultures. Therefore, at the end of 1980's total raptor populations in Delhi reached their peak of 3000-3400 pairs including 1800-2100 pairs of Black Kites and 1000-1200 pairs of White-backed Vultures. A crash of Vultures there seemed to occur at the beginning of 1990s. Until the middle of 1990s Delhi was probably inhabited with 2400-2700 pairs of raptors including 1700-1800 pairs of Kites and 700-800 pairs of White-backed Vultures.
Bearing in mind results of the above surveys a total density of birds of prey in Northern-Central India (c.50,000 sq.km) was not less than 25 breeding pairs per 10 sq.km. So, it could be presumed that overall raptor populations in agricultural and urban habitats there at the very beginning of 1970s had roughly consisted of at least 120-150 thousand breeding pairs including 70-75 thousand pairs of White-backed Vultures, 20-25 thousand pairs of Black Kites, 12-15 thousand pairs of Egyptian Vultures, and 5 thousand pairs each of Black-shouldered Kites and White-eyed Buzzards.
Thirty years ago raptor populations in Northern-Central India as a whole and within Delhi in particular appeared to be the highest in any urban area, worldwide. The major reasons for that were abundance of high trees for nesting, practical absence of electric power lines and many other threats to birds of prey in agricultural areas a large bulk of food in fact mostly provided by people (garbage, dead cattle, traffic kills, etc.) as well as traditional good-will attitude of Indians to all living beings including raptors.
Thus, there are reasons and basis to proceed the same kind of raptor surveys within the same sample areas by the same methodology in order to obtain exact comparative data on raptor populations under the new environmental conditions in North-Central India.
Ali S., Grubh R.B. 1984. Ecological study of bird hazards at Indian aerodromus. First Annual Report, Phase 2. Bombay Natural History Society.
Galushin V.M. 1969 [Large urban population of Black Kites in Delhi (India)].Ornithology in the USSR, Book 2. Materials of the 5th USSR Ornithological Conference, Ashkhabad, pp.161-164. [In Russian]
Galushin V.M. 1971. A huge urban population of birds of prey in Delhi, India (Preliminary note). Ibis, v.113, No 4, p.522.
Galushin V.M. 1974. A comparative analysis of the density of predatory birds in two selected areas within the Palearctic and Oriental regions: vicinities of Moscow and Delhi. Abstracts, 16 International Ornithological Congress, Canberra, p.144.
Galushin V.M. 1980. [Forest raptors]. “Lesnaya promyshlennost” Publication, Moscow, 160 p.
Galushin V.M. 1985. Adaptation of predatory birds to altered environmental conditions. Acta 18 Congressus Intern. Ornithologici, v.2, Moscow, pp.662-665.
Galushin V.M. 1992. Long-term changes in raptor populations in Delhi, India. Abstracts, IV World Conference on Birds of Prey and Owls. Berlin, p.7.
Galushin V.M. 1996. Birds of prey populations in grassland and agricultural habitats of Northern-Central India. Abstracts, Salim Ali Centenary Seminar on Conservation of Avifauna of Wetlands and Grasslands, Mumbai, India, p.20
Galushin V. and N. Zakharova-Kubareva. 1998. Nesting raptor populations within urban and agricultural habitats in Northern-Central India. Asian Raptor Research and Conservation. Program and Abstracts, First Symposium on Raptors in Asia. Shiga, Japan, p30.
Ganguli U. 1975. A guide to the birds of Delhi area. Indian Council of Agricultural Research, New Delhi, 301 p.
Hutson H.P.W. 1954. The birds about Delhi. Delhi Bird Watching Society, 210 p.
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Prakash V. 1999. Status of vultures in Keoladeo National Park, Bharatpur, Rajasthan, with special reference to population crash in Gyps species. Journal, Bombay Natural History Society, v.96, No 3, pp.365-378.
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Vyas S. 1996. Checklist of the birds of the Delhi region: an update. Journal, Bombay Natural History Society, v.93, No 2, pp.219-237.
Watson R. 2000. Vultures in crisis. Peregrine Fund, Newsletter No 31, pp.20-21.
In late 1998 The National Birds of Prey Centre was approached by Khojeste Mistree, a well known and respected theologian in the Parsi Faith, who had been advised to come to us by Dr David Houston. The Parsis have a rather singular problem which they hoped we could solve. The problem is that the Parsis believe earth, fire and water are sacred and therefore good, whereas the dead body of a human is thought to be evil in death. Thus they do not bury, cremate or otherwise dispose of bodies, as this would defile those elements they consider to be sacred. Instead they place the bodies out to be devoured by scavengers.
This system has worked well for at least 2000 years, and in Bombay in particular for 400 years. In the beginning, bodies were simply placed out for all scavengers. Over time, the ritual became more organized and towers were built, in which to place the bodies, this meant that only flying scavengers were able to utilize the resource and so vultures became the main scavenger to devour the Parsi dead.
When the Parsis moved to Bombay at the request of the British, they were given a piece of land for the specific purpose of building Towers of Silence for their dead. The land, a 57-acre hill, is amazingly untouched considering that it was originally outside Bombay, but is now completely surrounded by the city. Some of the trees are very old, and apart from being a little manicured, it is probably unchanged from 400 years ago, although now the only predators left are avian, rather than mammalian.
The Towers are cylindrical walls surrounding three tiers of carved stone. The outside tier is used for male bodies, the next for female and the inner most for children. In the center of the tower is a pit filled with charcoal and then lime. What is left of the bodies once the vultures have departed is swept into the pit and time, sunlight and weather reduces the bones to their molecular components. The towers in Bombay are up to 90 meters across, but personal family towers are as small as 4 meters across. The walls are from 4 to 6 meters high and two small iron doors provide the entrance to each tower.
When the system worked, vultures arrived at the towers in high numbers. I was told that in half an hour the entire body, except for the leg bones, would be gone. So it was a very efficient way of disposing of the dead. Looking at some of the towers, and being informed that the vultures would stand shoulder to shoulder round the top of the tower to be used, prior to the funeral, we estimated that there could have been three hundred or more vultures waiting on one of the larger towers. Once they had fed and rested, the vultures would fly out of the area.
Again from information given by people who remember, there were ample vultures in the 1960s and 1970s but numbers started to decline in the eighties. Certainly moving slaughter houses away from the area of the towers, to outside of Bombay, had some effect on the numbers. But in the 1990s the numbers had dropped dramatically and so the huge problem of how to deal with bodies (3/day) had become rather pressing.
I visited the Dungawadi, the land where the towers are situated, in January 1999. There were no vultures to be seen around Bombay, none at the towers and I was taken to various bone yards and slaughter areas where at no time did I see a vulture of any species. I did see hundreds of Kites, who were feeding in the towers, but the number and size of those birds was not sufficient to get the job done.
In January and September 2000 we met with the Parsi committee to discussed the possibility of building aviaries and having captive vultures there to eat the Parsi dead. Some of the points we considered were:
(1) Birds that fed on the bodies at the morning funeral, were probably different than those that fed later in the day. As a consequence the minimum number of birds which used the facility was at least twice the maximum which would have been observed at any one time.
(2) Although vultures will gorge when they are hungry, they will not do this on a daily basis.
(3) We estimate that in the end we could need upwards of 300 vultures and possible more.
(4) No one has tried to keep this large a number of vultures together in one place.
(5) Wild vultures defecate, cast and preen throughout ranging and roosting areas. Cages for captive birds would require regular maintenance to keep the birds and the area healthy and smelling and looking normal.
(6) Vulture fear response, vomiting, sometimes occurs when cages are cleaned. This would be rather less acceptable if the birds had been feeding on human remains
(7) Birds would need to be bred and the population become self sustaining. This requires careful marking, monitoring and breeding control of all birds.
(8) Wild birds most likely had a more varied diet than simply human remains. We did manage to get permission from the theologians to put either goat or sheep carcasses in a small private tower for the birds to have a little variety in their diet. This caused some concern in the early stages of discussion.
(9) We considered the effect on vultures if humans had died whilst being given various drugs.
(10) The possibility of birds getting overweight, and putting on large amounts of fat was considered.
(11) The pen for holding birds needs to be large enough for feeding, bathing, roosting, sunning and even some flying.
(12) Because of the netting required to keep vultures in, other birds, such including Kites (Milvus spp.) and crows (Corvus spp.) would not be able to gain access.
(13) Because it is important to find alternative ways to deal with animal carcasses throughout India due to the lack of vultures, it is therefore highly unlikely that the wild vulture population will ever recover to its previous population level.
(14) Even if numbers do increase, because of Bombay’s many airports, it is likely dangerous to encourage these large birds to fly across airplane flight paths.
(15) Because of the severe drop in vulture numbers and because adult birds are difficult to train and habituate to captivity and management regimes, young birds are preferable for this project. They would also give the Parsis more time to understand the maintenance and welfare of the vultures before having to learn about captive breeding techniques
(16) The captive vultures would need to have some veterinary monitoring to ensure their health.
(17) Finally, until our project is started we will be faced with the prospect of bringing sick birds into captivity. The only way to avoid this appears to be by bringing birds in from other countries.
Not all of the Parsis want to be eaten by vultures after they die. Some feel that this method is outdated and other approaches should be considered. In particular, in addition to working with vultures, there are proponents of a “Solar Panel Project,” in which huge solar reflectors would concentrate radiation on a body, reducing it to nearly nothing within a few days.
At present the Parsis have permission to take twenty pairs of vultures from the wild, and we have provided them with an aviary design. Because of India’s climate and destructive insects, they now need to have their own architects advise us and them on the best available materials to use. However they are now hoping to cover two dakhmas (Towers of Silence) with netting, so the original plans we developed will need further revision.
The theological and religious needs of the Parsis often make approaching this project difficult. Nevertheless I have always ensured that they understand that our main interest is in the conservation of the vultures first and foremost. We believe that this project could play an important role in assisting the Royal Society for the Protection of Birds, the Institute of Zoology, the Bombay Natural History Society and the National Birds of Prey Centre in their conservation efforts. In particular, we hope to allow monitoring and studies of the Parsi Captive Vulture Population and the Captive Breeding Programme, for research into the management of large captive vulture populations. This program will be most successful if all parties involved are able to work together, providing support and sharing information, much has occurred at this conference, towards the greater goal of conserving vultures in India for the future.
The discussion that followed the workshop on the declines of the Gyps vultures in India proceeded immediately after the last talk by Mrs. Jemima Parry-Jones. Notes of the discussion are as follows:
(1) J.-M. Thiollay noted that vultures in SE Asia have essentially disappeared, and that researchers should remember this fact as Indian vulture research and monitoring proceeds.
(2) Debbie Pain pointed out that in SE Asia other scavengers also have declined and habitat change has been drastic, so a different causative agent may have been at work in those situations.
(3) Ofer Bahat noted that they had observed head drooping in Gyps vultures in Israel, and that this was almost universally a sign of a weak or sick bird. He also pointed out that Gyps vultures have a wide thermoneutral zone and it seems unlikely that this behavior is associated with thermoregulation
(4) Alvaro Camiña noted that in Spain they had observed this behavior when birds were resting or quiet.
(5) Munir Virani followed this up with a note that Peter Mundy says that this behavior is common in wild vultures, however, it had rarely been noted in India before the current decline. Furthermore he cited confusion about the role of head dropping, and did note that it had only been observed in summers.
(6) Andrew Cunningham then suggested that head drooping is probably a normal behavior of some kind, but suggested that we are probably seeing it more than normal because it is a response to whatever is affecting the birds. He clearly indicated that the behavior is not a sign of a specific disease, but felt that it was important for people to realize that birds that did this a great deal did eventually die. He also suggested that it was important not to get hung up on the drooping head syndrome only and that irrefutably vultures were dying at an unprecedented rate and that was the important fact to remember.
(7) Oliver D. asked if we could correlate this behavior with other symptoms such as closed eyes and ruffled feathers
(8) Andrew Cunningham did say they had seen that.
(9) Lindsay Oaks noted that sick birds which did not droop heads have been observed.
(10) Debbie Pain suggested that head drooping behavior may be a way to monitor spread of a disease if that is causing the decline.
(11) Juan Rafael complimented everyone on working well together to solve the problem of declining vulture populations and noted that head drooping behavior did not appear to be birds becoming hypothermic. Rather he noted that when birds recover from anesthesia they often do this, and perhaps that it is related to circulation. Also, poisoned birds show gout, as these birds do, and he asked if it is possible that a bacterial toxin originating in food could be killing birds.
(12) A. Cunningham agreed that it is possible, but also that he expected a toxin to impact a wider range of species, and that most such disease is non-specific.
(13) L. Oaks agreed.
(14) David Houston noted that vultures have excellent immune systems and asked if it was possible that multiple factors could be interacting to weaken birds and make them more susceptible to disease.
(15) Miguel Cerveva asked if it would be possible to study disease in a captive bird and try to treat that.
(16) Debbie Pain and Andrew Cunningham responded that they wanted to try to do that before the end of December in their India facilities, and they would be trying treatments.
(17) Mr. Salazar reminded us that population growth rate should be sensitive to adult survival, and he asked Munir Virani if it was possible to get an estimate of adult survival.
(18) Munir responded that it was very difficult to estimate mortality, but that their estimates were based on birds they collected, and so could be seen as a minimum mortality rate.
(19) Vibhu Prakash also pointed out that they had tried ringing and radio-tagging birds, but they died too quickly to get a good survival estimate.
(20) Campbell Murn asked how vultures would be kept in captivity, and that often if vultures were kept alone, they did not do well.
(21) Jemima Parry-Jones said that she had designed pens to allow birds to live together wherever possible, but that some birds that were very sick would have to be isolated for health and monitoring reasons. However the process would be a learning curve as they worked with the vultures in captivity.
(22) Ohad Hatzofe pointed out that vultures are not the only carrion eaters, and we may not see lower numbers of other species. He suggested that it would be good to look for disease and contaminants in food and water, and he also kindly offered any assistance that might be had by providing knowledge gained by the many years of vulture research in Israel.
(23) Debbie Pain pointed out that the India problem was a nationwide one and that birds ate many food types, and therefore considered it unlikely that food was primarily to blame. She also noted that although it was possible that other birds were sick or declining, she considered it unlikely based on her understanding of the situation.
(24) Munir Virani then pointed out that pesticide use in India and Pakistan was excessive and many bird species were declining in regions where they were especially heavily used.
(25) Lindsay Oaks agreed, and added that they were asking people about the livestock carrion that was left out.
(26) Andrew Cunnningham noted that funds available were limited for research, and while that question was important, that it seemed more prudent for him to spend money on scenarios his research suggested was more likely. Toxicology was incredibly expensive difficult to know where to start. So far few of the deaths could be put down to poisons.
(27) M. Wallace asked how far birds fly on a daily basis.
(28) Vibhu Prakash responded and said that telemetered birds flew 50-60 km/day to find food, or possibly greater distances.
(29) Munir Virani also said that satellite telemetry was needed to find exactly how far these birds traveled.
(30) M. Wallace also noted that birds often flew long distances for seemingly no apparent reason.
Jemima Parry Jones concluded the session by thanking all the speakers and those who had attended in a somewhat crowded room. She also thanked Todd Katzner who had done so much work in helping to organize the workshop and taking copious notes of the discussion, and Disney’s Animal Kingdom and the Bird of Prey Taxon Advisory Group in the US who had helped with some funding. She emphasized that the problem for Gyps vultures across the Old World was potentially huge and it was important for everyone to work together and share information as much as possible. She pointed out that one of the learning points of the Californian Condor that must be taken into account was the lack of cohesion that sadly occurred and that must not happen here. She promised a report on the workshop as soon as possible. Dr Pain said that the report could go on the Vulture website that the RSPB had done. JPJ said that it would be as widely spread as she and Katzner could manage. Website addresses will be available on the report which will also be on the RRF site and NBPC.