Developing an oral bait for badger vaccination: factors influencing bait disappearance and behavioural responses

Abstract

The Eurasian badger (Meles meles) is believed to constitute an important wildlife reservoir of bovine tuberculosis (Mycobacterium bovis), and is wildly implemented in transmission of the disease to cattle. Recent work has demonstrated that Bacillus Calmette-Guérin (BCG) vaccination can induce a significant protective effect in badgers, with current research focusing on the best method of vaccinating wild badgers. Oral vaccination, using baits containing the BCG vaccine, is widely accepted as the most practical and desirable method of vaccinating a large number of badgers over a wide geographical area. This study acted to investigate the factors influencing the number of baits taken by badgers, and the behviour badgers exhibit towards baits, as the success of a vaccination campaign will be greatly affected by the number of badgers consuming vaccine laden baits. Using video surveillance we identified that badgers show preference behaviour, with strong smelling bait eliciting high levels of investigations and attempts to retrieve. Additionally smell was the only bait characteristics that influenced bait uptake in populations of badger naïve to supplementary feeding. A preference for taste was not consistent, with sweet and un-sweet being taken more often depending on social and environmental conditions. Season was found to influence bait disappearance and associated behaviours, and autumn appears the most favorable season to deploy an oral bait to badgers. Bait characteristics and deployment considerations that will aid the highest uptake of bait by badgers are proposed.