Exposure of nontarget wildlife to candidate TB vaccine baits deployed for European badgers

In the UK and Republic of Ireland, the European badger Meles meles is considered a maintenance host for bTB and is involved in transmission of infection to cattle. A badger vaccine delivered in an oral bait is currently under development as part of an ongoing effort to reduce levels of disease in the badger population. An oral vaccine would likely be deployed in close vicinity to badger burrows (setts), such that bait will most likely be taken by the target species. However, a range of nontarget species may also occur close to badger setts, and some may potentially interfere with or consume baits. In this study, we used surveillance cameras to record the presence of nontarget species at 16 badger setts involved in a bait deployment study in southwest England. We recorded significant levels of nontarget species activity close to badger setts. The most commonly observed species were small rodents, which were observed at all setts, and in some cases accounted for >90 % of nontarget species observations. A total of 11 other nontarget species were also observed, indicating that a broad range of species may potentially come into contact with vaccine baits deployed at badger setts. Although the majority of these species were not observed interacting directly with baits, small rodents and squirrels were observed eating baits in a number of instances. In addition, monitoring of bait disappearance at 24 setts indicated that small rodents may take >30 % of bait deployed at some setts. The implications for the deployment of an oral vaccine for badgers are discussed.