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.

铅中毒是对人类健康和大量野生生物的重要威胁。动物会暴露于突出显示狩猎弹药的铅的几种来源以及表土中可生物利用的铅。弄清每种物质在铅接触中的作用是一个重要的保护问题，特别是对于潜在受铅中毒影响的物种（例如秃鹰）而言。秃鹰和其他物种中铅源的识别已通过稳定同位素比较经典地解决，但是当弹药与表土签名重叠时，在弹药中发现的同位素签名极为不同。此外，在不了解鸟类利用实际饲养场的情况下，做出了与单个秃鹰暴露于铅源相关的假设。这里，我们结合了血液中铅的浓度分析，新颖的稳定同位素方法来确定铅的来源和GPS跟踪数据，以调查两个伊比利亚狮riff秃population种群（N = 58）的主要觅食地，其觅食范围因表土铅浓度而不同和大型狩猎活动的强度。我们发现，秃鹰的铅签名更接近表土而不是弹药，但是在大型狩猎活动较高的地区，这种相似性显着降低。此外，考虑到被追踪鸟类的个体栖息地，解释狩猎活动强度的模型可以更好地解释秃鹰中的血铅浓度高于表土暴露。尽管如此，我们的发现还表明，表土中铅的暴露比以前认为的更为重要。