Journal of Ornithology

, Volume 150, Issue 2, pp 495–503 | Cite as

High mortality and sex ratio imbalance in a critically declining Oriental White-backed Vulture population (Gyps bengalensis) in Pakistan

  • Muhammad ArshadEmail author
  • Muhammad J. I. Chaudhary
  • Michael WinkEmail author
Original Article


Populations of Oriental White-backed Vulture (Gyps bengalensis) and Long-billed Vulture (Gyps indicus) declined dramatically by 95–100% on the Indian subcontinent in during the mid-1990s. The study reported here was conducted in Pakistan to compare the population size, breeding success, patterns of mortality and sex ratios among dead vultures and newly hatched nestlings of G. bengalensis and G. indicus at Toawala (TW) and Nagar Parkar (NP), respectively, during the breeding seasons 2005/2006 and 2006/2007. At TW, diclofenac poisoning was most likely responsible for the high mortality and sex ratio imbalance among dead G. bengalensis, where vulture counts and breeding success declined quickly during the study period. However, at NP no significant difference in population size, breeding success and annual mortality of G. indicus was recorded during the study period. A sex ratio imbalance was detected among nestlings of G. bengalensis, with 68% males and 32% females. In contrast, the sex ratio did not differ significantly in G. indicus.


Breeding success Gyps bengalensis Gyps indicus Mortality Sex ratio Vulture count 



This project was supported by a fellowship of the Deutscher Akademischer Austausch Dienst to M.A. We are very grateful to many people who helped us with the field work. We thank Hedi Sauer-Gürth for her help in the laboratory as well as Theodor C. H. Cole for improving the English of the manuscript.


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Copyright information

© Dt. Ornithologen-Gesellschaft e.V. 2009

Authors and Affiliations

  1. 1.Department of Biology, Institute of Pharmacy and Molecular Biotechnology (IPMB)University of HeidelbergHeidelbergGermany
  2. 2.Department of ZoologyBahauddin Zakariya UniversityMultanPakistan

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