Ranging behaviour of badgers Meles meles vaccinated with Bacillus Calmette Guerin

Because biological systems are complex, management interventions occasionally have unintended adverse consequences. For example, attempts to control bovine tuberculosis (TB) by culling badgers Meles meles have, under some circumstances, inadvertently increased cattle TB risks. Such harmful effects occur because culling profoundly alters badger movement behaviour, increasing pathogen transmission both between badgers and from badgers to cattle. It has recently been suggested that another TB management tool, badger vaccination with Bacillus Calmette Guerin, might provoke similar behavioural changes and hence similar harmful effects for cattle. We therefore took advantage of an existing project, which monitored 54 GPS-collared badgers across four study sites in southwest Britain, to explore whether vaccination, or live trapping to administer vaccine, influenced badger movement behaviour. We detected no significant effects of either vaccination or trapping on badgers’ monthly home range size, nightly distance travelled, or frequency of trespassing in neighbouring territories. The estimated effect of vaccination on badger home range size [2% reduction, 95% confidence interval (CI) 18% reduction – 17% increase] was statistically non-significant, but significantly smaller than that associated with both widespread (180% increase, 95% CI 70–362% increase; P < 0·001) and localised badger culling (74% increase, 95% CI 4–191% increase; P = 0·038). Synthesis and applications. In contrast with culling, live trapping and vaccinating badgers did not measurably alter their movement behaviour, fuelling optimism that vaccination might contribute positively to cattle tuberculosis control. Our study illustrates how existing monitoring can be exploited to assess potentially adverse effects of wildlife management