High risk of lead contamination for scavengers in an area with high moose hunting success

PLoS One. 2014 Nov 12;9(11):e111546. doi: 10.1371/journal.pone.0111546. eCollection 2014.

Abstract

Top predators and scavengers are vulnerable to pollutants, particularly those accumulated along the food chain. Lead accumulation can induce severe disorders and alter survival both in mammals (including humans) and in birds. A potential source of lead poisoning in wild animals, and especially in scavengers, results from the consumption of ammunition residues in the tissues of big game killed by hunters. For two consecutive years we quantified the level lead exposure in individuals of a sentinel scavenger species, the common raven (Corvus corax), captured during the moose (Alces alces) hunting season in eastern Quebec, Canada. The source of the lead contamination was also determined using stable isotope analyses. Finally, we identified the different scavenger species that could potentially be exposed to lead by installing automatic cameras targeting moose gut piles. Blood lead concentration in ravens increased over time, indicating lead accumulation over the moose-hunting season. Using a contamination threshold of 100 µg x L(-1), more than 50% of individuals were lead-contaminated during the moose hunting period. Lead concentration was twice as high in one year compared to the other, matching the number of rifle-shot moose in the area. Non-contaminated birds exhibited no ammunition isotope signatures. The isotope signature of the lead detected in contaminated ravens tended towards the signature from lead ammunition. We also found that black bears (Ursus americanus), golden eagles and bald eagles (Aquila chrysaetos and Haliaeetus leucocephalus, two species of conservation concern) scavenged heavily on moose viscera left by hunters. Our unequivocal results agree with other studies and further motivate the use of non-toxic ammunition for big game hunting.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Wild*
  • Birds
  • Crows
  • Eagles
  • Environmental Monitoring
  • Food Chain
  • Isotopes / analysis
  • Lead / analysis
  • Lead / blood
  • Lead Poisoning / etiology*
  • Models, Statistical
  • Quebec
  • Ursidae

Substances

  • Isotopes
  • Lead

Grants and funding

This study was supported by the Ministère du Développement Durable, de l'Environnement, de la Faune et des Parcs; the Fondation de la faune du Quebec (Programme « Protection, mise en valeur et aménagement des habitats fauniques », and Programme « Faune en danger »), and the Université du Quebec à Rimouski. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.