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.

This work gives a clear indication of the levels of neonicotinoids in arable soils after typical use of these compounds as seed dressings in the United Kingdom. There was evidence that imidacloprid was more persistent in the soils studied than clothianidin and thiamethoxam. As clothianidin and thiamethoxam have largely superseded imidacloprid in the United Kingdom, neonicotinoid levels were lower than suggested by predictions based on imidacloprid alone.

wrote the paper.The authors declare no conflict of interest. This article is a PNAS Direct Submission.Published under the PNAS license.Data deposition: The datasets generated and analyzed during the current study are available in the University of Exeter ORE repository, https://ore.exeter.ac.uk/repository/ (

No abstract

Chemical markers are increasingly used to investigate consumption of baits used to deliver vaccines, toxicants, and contraceptives. We evaluated whether ethyl‐iophenoxic acid (Et‐IPA) and propyl‐iophenoxic acid (Pr‐IPA) can be used as long‐lasting systemic bait markers for wild boar (Sus scrofa). We presented captive wild boar with baits treated with either Et‐IPA or Pr‐IPA at 5 mg/kg (low dose), 10 mg/kg (medium dose), and 20 mg/kg (high dose) of body weight. We collected serum from each boar at 5 time points: 5 days, 3 weeks, 6 weeks, 11 weeks, and 39 weeks following ingestion of iophenoxic acid‐treated baits. We detected both Et‐IPA and Pr‐IPA for ≥39 weeks after ingestion. Throughout the trial, the Et‐IPA we found in serum was proportional to the amount eaten. At each time point, animals in the high‐dose group had significantly more Et‐IPA than animals in the low‐dose group. We concluded that both compounds can be used as long‐lasting markers in wild boar and that Et‐IPA can also be employed as quantitative marker to indicate multiple bait uptake. Both compounds have potential applications in the context of vaccination, fertility, and population control campaigns, where baits are used to deliver pharmaceuticals, and in behavioral studies to establish spatial and temporal patterns of bait uptake.