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Summary of Field Study Results from Pakistan for the Breeding Season 2000/2001
Published 2 December 2001
In October 2000, The Peregrine Fund and partners began parallel field studies in Pakistan and Nepal to identify and understand the cause of vulture mortalities and subsequent declines in the Indian subcontinent. Studies in India had found:
1. Extensive declines of Gyps
vulture populations across India
2. Unusually large numbers of dead vultures
3. Unexplained renal failure manifested as visceral gout in vultures examined post mortem.
GOALS AND OBJECTIVES
Our goal is to understand the cause of population decline, and specifically, cause of renal failure and mortality in south Asian vultures.
Our objectives in 2000/2001 were:
1. To measure the rates of mortality among Oriental White-backed Vultures of each age-class and identify temporal, spatial and other patterns in mortality that would help reveal the underlying cause of mortality in these birds;
2. To identify the causes of death wherever possible through necropsy and diagnostic evaluation of tissue samples;
3. To measure breeding productivity and understand other behaviors that may affect the species' population dynamics
We established three primary study sites in Punjab Province of Pakistan where significant populations of Oriental White-backed Vultures continued to exist. Dholewala (near Taunsa Barrage), Toawala (near Multan) and Changa Manga Forest (south of Lahore) are our three main study areas, and were monitored on a regular basis throughout the breeding season. We are also monitoring 15 other secondary sites on an irregular basis including Katora Forest (near Bahawalpur), Dinga Nala (near Ghazi Ghat) and Chichawatni Forest.
We located all Oriental White-backed Vulture nests in our primary study areas. Intensive study transects containing ~200 nests were randomly selected and marked for constant monitoring. Nest activity was recorded at least twice weekly throughout the breeding season, and we collected all dead vultures that were located. Wherever possible we conducted post mortem examinations on dead vultures to assess the presence or absence of visceral gout. In cases where decomposition was not advanced tissue samples were collected for diagnostic analysis.
–In the 2000/2001 breeding season we located a sample of 3980 Oriental White-backed Vulture nests in the Punjab Province of Pakistan, of which 2430 were considered to be active;
–At Dholewala 62% of 246 active nests in intensive transects fledged young;
–At Toawala 54% of 230 active nests in intensive transects fledged young;
–At Changa Manga 59% of 197 active nests in intensive transects fledged young; Mortality
–We collected 673 dead vultures across all sites during the study period December 2000 (winter) and July 2001 (summer);
–Dead adult and subadult were found throughout the study period with no obvious seasonal peaks;
Annual adult mortality was calculated to be 18.6% in Changa Manga;
–Annual adult mortality was calculated to be 11.4% in Dholewala;
–Annual adult mortality was calculated to be 2.3% in Toawala;
–High rates of juvenile mortality occurred around fledging (April-May), mostly due to injuries sustained during early flights and starvation and dehydration of young birds unable to return to the nest to be fed.
–Between April and July 36% of fledglings were found dead in intensive transects at Changa Manga;
–Between April and July 28% of fledglings were found dead in intensive transects at Dholewala;
Between April and July 24% of fledglings were found dead in intensive transects at Toawala;
Post mortems were performed on 190 Oriental White-backed Vultures;
–Visceral gout was found in 80% of adults, 63% of subadults, 19% of fledglings and 13% of nestlings;
–Large numbers (compared to India) of Oriental White-backed Vultures are still present in the Punjab Province of Pakistan in 2000/01, but high adult mortality is indicative of a rapidly declining population;
–The presence of visceral gout in 80% of adult and 63% of sub-adult vultures indicates that the single largest cause of mortality in these age-classes in Pakistan is likely the same reported to be causing vulture deaths in India;
–Dead nestlings and fledglings were also found with visceral gout, but accounted for a much smaller proportion of mortality than in adults and sub-adults. Survival rates in juvenile Gyps
vultures are typically lower than those of adult birds (Sarrazin 1994). Studies of Cape Vultures G. coprotheres
in Africa have recorded high first year mortality rates of 50 to 83% (Houston 1974, Piper et al.1981). Therefore we might expect the incidence of visceral gout to be lower in this age group due to a higher ‘background’ mortality rate;
–Breeding success of 50-60% is comparable to studies of Gyps
vultures in Africa, and suggests that breeding failure is not responsible for the species’ decline.
REFERENCES AND FURTHER READING
Benson, P.C. 2000. Causes of Cape Vulture Gyps coprotheres
mortality at the Kransberg colony: a 17 year update. In Raptors at Risk. Chancellor, R.D. & B.U. Meyburg [eds]. Proceedings of the 5th World Conference on Birds of Prey and Owls, Midrand South Africa 1998.
Grimmet R, Inskipp, C and Inskipp, T. 1998. Birds of the Indian subcontinent. Christopher Helm, London.
Houston, D. C. 1979. The adaptation of scavengers. Pp 263 - 286. Chapter in Serengeti, dynamics of an ecosystem. Editors Sinclair, A. R. E. & Norton Griffiths, M. Chicago University Press.
Neelkanthan, S. 2000. Are feeding stations likely to save vultures? Times of India October 25th 2000 issue.
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. 2000. A Progress Report on Status and Distribution of Gyps Species of Vultures in India. Bombay Natural History Society. Mumbai. 46 pp.
Rahmani, A. & V. Prakash 2000. A brief report on the international seminar on vulture situation in India. BNHS, New Delhi 18th to 20th September 2000.
Rasmussen, P.C. & Parry, S.J.. On the specific distinctness of the Himalayan Long billed Vulture Gyps [indicus] tenuirostris. Abstract, p. 64, 118th Stated Meeting of the American Ornithologists' Union, Memorial University of Newfoundland, St. John's, Newfoundland.
Roberts, T.J. 1991. The Birds of Pakistan. Volume 1. Oxford University Press. Karachi and Oxford.
Sarrazin, F., Bagnolini, C., Pinna, J.-L., Danchin, E. & Clobert, J. (1994) High survival estimates of griffon vultures (Gyps fulvus fulvus) in a reintroduced population. Auk 111: 853-862.
The Asian Vulture Crisis Project is managed and supported by The Peregrine Fund with financial support from the Gordon and Betty Moore Foundation, UN Foundation, Disney Company Foundation and 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), Brigadier Mukhtar Ahmed and WWF Pakistan, 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, Department of National Parks and Wildlife Conservation (DNPWC);
–in the USA, the Zoological Society of San Diego, Washington State University, The Raptor Center, University of Wisconsin, and The Bodega Bay Institute, and many others.