Assessment of lead exposure risk for raptors distributed in Honshu using hunting statistics data

Abstract

The risk assessment of lead exposure in raptors utilized data on firearm-related hunting activities selected from hunting statistics. The occurrence of lead poisoning in raptors in overseas and Hokkaido has shown that lead bullets are the most important source of lead contamination in raptors. Our research also revealed that (i) raptors are attracted to carcass waste of hunted animals in Honshu as in Hokkaido, (ii) predation of waterfowls by raptors has been observed in Honshu, (iii) lead concentrations in game meat were below detection limits, and (iv) some waterfowls showed high levels of blood lead concentration. Consequently, it's likely that the lead contamination source in raptors distributed in Honshu is related to lead ammunition, such as lead fragments in carcass waste and lead pellets in waterfowls. For lead exposure risk assessment, the distribution of four raptor species (Northern Goshawk, Peregrine Falcon, Mountain hawk-eagle and Golden Eagle) and firearm-related hunting activity data were integrated to identify areas as 'hotspots' where raptors are distributed and where firearm-related hunting is active. Analysis of the proportion of hotspots within their distribution areas showed Northern Goshawks and Peregrine Falcons have a high proportion of distribution in high-risk hotspots, indicating significant lead exposure risk. Conversely, Mountain hawk-eagle were distributed in medium to low-risk areas, Golden Eagle mainly found in low-risk areas. Moreover, data for four species were integrated to identify areas with a high diversity of raptors and significant hunting activity. As a result, it was possible to identify areas where raptors are at particular risk of exposure to lead via lead ammunition. Prioritizing the regulation of hunting using lead ammunition in these areas could reduce the risk of lead exposure to endangered raptors.