Breeding and mortality of Oriental White-backed Vulture Gyps
bengalensis in Punjab Province, Pakistan
Martin Gilbert a1, Munir Z. Virani a1, Richard T. Watson a1, J. Lindsay Oaks a2, Patrick C. Benson a3, Aleem A. Khan a4, Shakeel Ahmed a4, Jamshed Chaudhry a4, Muhammad Arshad a4, Shahid Mahmood a4 and Qaswar Ali Shah a4
a1 The Peregrine Fund, 5668 West Flying Hawk Lane, Boise, Idaho, 83709, USA. E-mail: mart gilbert@yahoo.com
a2 Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington 99164-7040 USA
a3 School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3, P.O. WITS, 2050, Johannesburg, Republic of South Africa
a4 Ornithological Society of Pakistan, 109/D P.O Box 73, Dera Ghazi Khan, Pakistan
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AbstractPopulations of Oriental White-backed Vulture Gyps
bengalensis and Long-billed Vulture G.
indicus declined in India between the mid 1980s and late 1990s. Regional reports from India described declines of 95–100% across a wide area. This study was conducted to investigate the breeding success and pattern of mortality in two vulture colonies (Dholewala and Changa Manga) within Punjab Province, Pakistan between December 2000 and June 2001. Breeding success was found to be 62% in Dholewala and 59% in Changa Manga. A total of 668 sick and dead vultures were collected of which 591 were less than one month post
mortem. No significant variation was found in the weekly mortality rate of adult and subadult vultures during the study period spanning winter through summer. A peak in mortality rate was observed during late April and early May that corresponded to mortality of newly fledged juveniles. Minimum annual mortality rate in the adult breeding population was calculated to be 11.4% and 18.6% in Dholewala and Changa Manga respectively. In a subsample of dead vultures (n = 185) visceral gout was found in 80% of adults, 63% of subadults, 19% of juveniles and 13% of nestlings. These mortality rates were consistent with a rapid population decline. Results imply that the mortality factor responsible for the decline in Gyps vultures described in India is also present in Pakistan and will potentially lead to a population decline of a comparable magnitude.
(Received January 15 2002)
(Revised July 5 2002)
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