1 research outputs found
Dust and bullets: stable isotopes and GPS tracking disentangle lead sources for a large avian scavenger
Lead intoxication is an important threat to human health and a large number of
wildlife species. Animals are exposed to several sources of lead highlighting hunting
ammunition and lead that is bioavailable in topsoil. Disentangling the role of each in
lead exposure is an important conservation issue, particularly for species potentially
affected by lead poisoning, such as vultures. The identification of lead sources in
vultures and other species has been classically addressed by means of stable-isotope
comparisons, but the extremely varied isotope signatures found in ammunition hinders
this identification when it overlaps with topsoil signatures. In addition, assumptions
related to the exposure of individual vultures to lead sources have been made without
knowledge of the actual feeding grounds exploited by the birds. Here, we combine lead
concentration analysis in blood, novel stable isotope approaches to assign the origin of
the lead and GPS tracking data to investigate the main foraging grounds of two Iberian
griffon vulture populations (N=58) whose foraging ranges differ in terms of topsoil lead
concentration and intensity of big game hunting activity. We found that the lead
signature in vultures was closer to topsoil than to ammunition, but this similarity
decreased significantly in the area with higher big game hunting activity. In addition,
attending to the individual home ranges of the tracked birds, models accounting for the
intensity of hunting activity better explained the higher blood lead concentration in
vultures than topsoil exposure. In spite of that, our finding also show that lead exposure
from topsoil is more important than previously thought