Did Vulture Decline Increase Death Rates in India?

Abstract

This commentary critically evaluates the methodology and conclusions of a recent study by Frank and Sudarshan[1] which links the decline of vulture populations in India to an estimated half-million excess human deaths between 2000 and 2005. Utilizing data from India’s Civil and Sample Registration Systems, Frank and Sudarshan attributed the claimed rise in human mortality to the ecological consequences of vulture loss, notably increased feral dog populations and associated rabies, waterborne diseases, and other health hazards. By examining the data reliability as well as independent analysis of the same data, we identify significant limitations in data reliability, potential confounding factors, and the robustness of the study’s statistical assumptions. Our findings question the strength of the patterns themselves and further the soundness of the causal claims, suggesting that improvements in mortality records and many other factors may potentially explain the observed trends. With the current limitations of data, there is no reliable way to estimate quantitatively the human health consequences of vulture decline.