Blood lead levels in an endangered vulture decline following changes in hunting activity

L Gangoso; R Mateo; C Santamaría-Cervantes; M García-Alfonso; C Gimeno-Castellano; E Arrondo; D Serrano; T van Overveld; M de la Riva; M A Cabrera; J A Donázar

doi:10.1016/j.envres.2024.118712

Blood lead levels in an endangered vulture decline following changes in hunting activity

Environ Res. 2024 Mar 26;252(Pt 1):118712. doi: 10.1016/j.envres.2024.118712. Online ahead of print.

Authors

Affiliations

¹ Department of Biodiversity, Ecology and Evolution, Faculty of Biological Sciences, Complutense University of Madrid, C/ José Antonio Novais 12, 28040, Madrid, Spain. Electronic address: lgangoso@ucm.es.
² Instituto de Investigación en Recursos Cinegéticos-IREC, CSIC-UCLM-JCCM, Ronda de Toledo 12, 13005, Ciudad Real, Spain.
³ Department of Conservation Biology, Estación Biológica de Doñana (CSIC), Américo Vespucio 26, 41092, Sevilla, Spain.
⁴ Department of Conservation Biology, Estación Biológica de Doñana (CSIC), Américo Vespucio 26, 41092, Sevilla, Spain; Department of Zoology, University of Granada, Avenida Fuente Nueva s/n, 18071, Granada, Spain.
⁵ Dirección general de Espacios Naturales y Biodiversidad. Consejería de Transición Ecológica y Energía, Gobierno de Canarias, C/ Prof. Agustín Millares Carló, 18, 35071, Las Palmas de Gran Canaria, Spain.

PMID: 38548255
DOI: 10.1016/j.envres.2024.118712

Abstract

Lead ammunition stands out as one of the most pervasive pollutants affecting wildlife. Its impact on bird populations have spurred efforts for the phase-out of leaded gunshot in several countries, although with varying scopes and applications. Ongoing and future policy changes require data to assess the effectiveness of adopted measures, particularly in the current context of biodiversity loss. Here, we assessed the long-term changes in blood lead (Pb) levels of Egyptian vultures from the Canary Islands, Spain, which have been severely affected by Pb poisoning over the past two decades. During this period, the reduction in hunting pressure and changes in legislation regarding firearms usage for small game hunting likely contributed to a decrease in environmental Pb availability. As anticipated, our results show a reduction in Pb levels, especially after the ban on wild rabbit hunting with shotgun since 2010. This effect was stronger in the preadult fraction of the vulture population. However, we still observed elevated blood Pb levels above the background and clinical thresholds in 5.6% and 1.5% of individuals, respectively. Our results highlight the positive impact of reducing the availability of Pb from ammunition sources on individual health. Nonetheless, the continued use of Pb gunshot remains an important source of poisoning, even lethal, mainly affecting adult individuals. This poses a particular concern for long-lived birds, compounding by potential chronic effects associated with Pb bioaccumulation. Our findings align with recent studies indicating insufficient reductions in Pb levels among European birds of prey, attributed to limited policy changes and their uneven implementation. We anticipated further reductions in Pb levels among Egyptian vultures with expanded restrictions on hunting practices, including a blanket ban on Pb shot usage across all small game species.

Keywords: Canary islands; Egyptian vulture; Pb gunshot policy; Pb intoxication; Small game.