Livestock Drugs and Disease: The Fatal Combination behind Breeding Failure in Endangered Bearded Vultures

Blanco, Guillermo; Lemus, Jesús A.

Environmental pollutants are increasingly documented as a driver of wildlife endangerment due to their roles in organ damage, hormonal disruption and alteration of the immune system [1, 2] . Disease may also facilitate endangerment and extinction at global and local scales, especially when pathogens interact with other drivers such as pollutants [3] . There is increasing concern about the impact of veterinary drugs and livestock pathogens as factors damaging wildlife health [4] [5] [6] , and even causing declines approaching extinction [7] . These threats may be especially detrimental to wildlife as they increasingly concur and interact as a consequence of the elimination of livestock residues containing veterinary pharmaceuticals and resistant pathogens due to growing intensive livestock operations worldwide [6, 8, 9] . In particular, the ingestion of antimicrobials, primarily fluoroquinolones, has been recently related to immunodepression-mediated acquisition of opportunistic pathogens and disease, as well as to organ damage in nestling vultures [6, 10, 11] . Fluoroquinolone residues have also been found in avian scavenger eggs and are associated with severe alterations in the development of embryo cartilage and bones that could preclude embryo movement and subsequently normal development, pre-hatch position and successful hatching [12] . Therefore, antimicrobials and other drugs may negatively affect embryo and nestling health with potentially devastating consequences on breeding success and conservation of vultures and other threatened avian scavengers.