Diclofenac poisoning is widespread in declining vulture populations across the Indian subcontinent

Abstract

Recent declines in the populations of three species of vultures in the Indian subcontinent are among the most rapid ever recorded in any bird species. Evidence from a previous study of one of these species, Gyps bengalensis, in the Punjab province of Pakistan, strongly implicates mortality caused by ingestion of residues of the veterinary non-steroidal anti-inflammatory drug diclofenac as the major cause of the decline. We show that a high proportion of Gyps bengalensis and G. indicus found dead or dying in a much larger area of India and Nepal also have residues of diclofenac and visceral gout, a post-mortem finding that is strongly associated with diclofenac contamination in both species. Hence, veterinary use of diclofenac is likely to have been the major cause of the rapid vulture population declines across the subcontinent.

Role of Cyclonic Storm as Natural Disaster and other Factors on Vulture Mortality in India

“…Long-billed vulture population was similarly reduced about 97 % between 1985 and 1999 in Keoladeo National Park [23]. Similar observations were noticed by several authors in some other south Asian countries such as Nepal and Pakistan [10, 15,[24][25][26][27][28].…”

“…Postmortem analyses of vulture carcasses from different locations have found traces of diclofenac and its derivative compounds in their tissues, while the biomagnification of the drug diclofenac in vultures is believed to be the sole cause of mass mortality of their population. Many authors states that diclofenac contributes to renal failure and hepatotoxicity, is the only cause of vulture population decline in India [11][12][13][14][15][16][17][18]28,34,[56][57][58][59][60]. However, the available reports are inadequate for arguing whether diclofenac is the only main cause of vulture mortality or whether, following diclofenac biomagnification, the increased susceptibility of vultures to microbial pathogens, diseases or physiological disorders, such as OS followed by metabolic depression, is responsible for their mortality in large scale [29].…”

Avian scavengers and the threat from veterinary pharmaceuticals

“…Evidence has demonstrated (i) the presence of extensive visceral gout (deposits of the excretory product uric acid) in tissues of the majority of wild Gyps vulture carcasses recovered from Pakistan, India and Nepal [13,14]; (ii) the proportion of dead wild vultures with visceral gout is consistent with its cause being sufficient to produce the observed rapid rates of population decline [15]; (iii) a perfect association between the presence of gout and diclofenac residues in liver and kidney samples from dead wild vultures [13,14]; (iv) that experimental dosing of captive vultures with diclofenac quickly leads to the death of the treated birds with visceral gout [13,16]; (v) that residues of diclofenac sufficient to kill vultures remain in the tissues of cattle dying within a few days of receiving a standard veterinary dose of diclofenac [13,17]; and (vi) that the prevalence and concentration of diclofenac in available ungulate carcasses was sufficient to cause population declines at the rates observed [18]. This evidence indicates that 'diclofenac is the main, if not the only cause of the widespread declines in vulture populations' seen on the Indian sub-continent [15].…”

Two decades of cumulative impacts to survivorship of endangered California condors in California

“…Increasing independence in this population has contributed to recent increases in lead-related mortality, which are also likely evident from improved detection in the post-ban period with fewer deaths from undetermined causes. Similar to other vulture populations experiencing declines worldwide (Fisher et al, 2006;Ogada et al, 2012;Shultz et al, 2004), California condors are susceptible to large-scale poisoning events as a result of communal foraging behavior that puts several individuals at risk of exposure to a single contaminated carcass (Ogada et al, 2012). Progress toward recovery is not sustainable if the level of management required to ameliorate the threat of lead poisoning for the condor population remains the same, as the majority of investment has been put forth to reducing mortality rates rather than improving the viability of the reintroduced populations (Walters et al, 2010).…”