PLoS One. 2014 Nov 12;9(11):e111546. doi: 10.1371/journal.pone.0111546. eCollection 2014.
- 1Département
de biologie, chimie et géographie & Centre d'études nordiques,
Université du Quebec à Rimouski, Rimouski, Quebec, Canada.
- 2Ministère du Développement durable, de l'Environnement, de la Faune et des Parcs, Quebec, Quebec, Canada.
- 3Sciences and Technology Branch, Environment Canada, Quebec, Quebec, Canada.
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.
