Lead exposure and source attribution for a mammalian scavenger before and after a culling program

Lead-based ammunition is a significant source of environmental lead and threatens species that scavenge lead-shot carcasses, particularly in areas with intensive shooting. With the impacts of lead on avian scavengers well established, there is increasing focus on the effects of lead on mammalian scavengers. We investigated lead exposure in a morphologically specialized mammalian scavenger, the Tasmanian devil (Sarcophilus harrisii), by analyzing their blood lead levels (BLLs) before and after a marsupial culling program using linear mixed effects models. We compared lead isotope signatures in devil blood to those in the culling ammunition to inform potential source attributions. We sampled 23 devils before culling and 15 after culling, finding no significant difference in mean BLLs pre and post-culling. However, devils captured closer to forestry coupes where culling had occurred had higher BLLs, and a greater proportion of devils displayed elevated BLLs post-culling (33 % compared to 18 % pre-culling). The highest BLL (7.93 μg/dL) was found in a devil post-culling and this individual had lead isotope signatures that matched the ammunition samples analyzed, suggesting the individual was exposed to lead from scavenging on culled carcasses. While 18 % of the devil blood lead samples had isotope signatures consistent with the ammunition samples, most were measurably different, indicating other sources of lead in the landscape. BLLs in our study landscape were similar to published BLLs for wild devils across Tasmania. That said, lead isotope signatures in the blood of individual devils sampled both before and after culling shifted closer to those of ammunition samples post-culling. Our results indicate that while some individual devils may have been exposed to lead from culling, most devils in the landscape did not show evidence of recent exposure. However, even low lead levels can adversely impact wildlife health and immunity, a particular concern for devils, a species endangered by disease.