Bird Conservation International

Ecology and Conservation of Vultures

The impacts of La Niña-induced drought on Indian Vulture Gyps indicus populations in Western Rajasthan

JONATHAN C. HALLa1a2 c1, ANIL K. CHHANGANIa3, TOM A. WAITEa1a2 and IAN M. HAMILTONa1a2

a1 Department of Evolution, Ecology, and Organismal Biology, Ohio State University, Columbus, Ohio 43210, USA

a2 Department of Mathematics, Ohio State University, Columbus, Ohio 43212, USA.

a3 Department of Zoology, JNV University, Jodhpur 342001, India.

Summary

Previous research on the catastrophic decline of the Gyps species complex has identified diclofenac, a non-steroidal anti-inflammatory drug administered to livestock, as the primary cause. Large-scale climatic phenomena, such as ENSO-induced drought, however have not been examined. Based on time series analysis of annual count data, 1996–2005, we provide evidence that ENSO synchronised population dynamics throughout western Rajasthan. Here, we ask whether El Niño Southern Oscillation (ENSO) can also explain the population dynamics of the Critically Endangered Indian Vulture Gyps indicus. We attribute this impact largely to two La Niña events, including the major event spanning 1999. We also examine between-village variation in resident vulture populations. Our results suggest that in several villages, Indian Vulture populations may have been partially buffered from the negative effects of drought when compared to other villages in the study. Finally, we discuss potential causes of buffering in these villages.

(Received October 19 2010)

(Accepted April 29 2011)

(Online publication December 05 2011)

Correspondence:

c1 Author for correspondence; e-mail: hall.1073@osu.edu