Badger culling plan could backfire

Bovine tuberculosis has long been a scourge on the cattle farming industry. While there’s a low risk of people contracting it nowadays, the disease killed 1,500 people per year in Britain in the 1930s. Thousands of cattle are killed every year in the British Isles to keep bovine TB in check. But such control efforts are thwarted by wild European badgers (Meles meles), who can carry the causative agent, Mycobacterium bovis. Over the years, a variety of plans have been proposed and implemented to cull badgers, but new research suggests this approach may be counterproductive: Culling badgers, they say, actually makes the problem worse.

Following the public’s angry response to the Randomized Badger Culling Trial, which removed large numbers between 1998 and 2006, British officials pushed a new small-scale plan to cull only infected badgers and vaccinate healthy ones. Test-Vaccinate/Remove (TVR) will be piloted in Northern Ireland this year. No such plan can catch every badger, though. If some infected animals are missed, or if the vaccine proves less than effective, then the plan would leave behind infected or susceptible badgers.

To predict the impact of those remaining badgers, a U.K. team led by Rosie Woodroffe from the Institute of Zoology analyzed badger movement in 826 social group territories where removal operations of varying kinds occurred between 1986 and 1998. According to their research, four things happened when small numbers of badgers were culled: The remaining badgers expanded their range, badgers immigrated to new social groups more frequently, genetic relatedness within a badger group decreased, and the prevalence of Mycobacterium bovis increased.

As it turns out, culling as few as just one badger can perturb the remaining ones, causing them to act in ways that increase the spread of bovine TB among themselves and to cattle. That means that like large-scale culling, selective TVR and ongoing illegal badger kills could exacerbate the problem. Even the best-laid plans can’t account for badger behavior. — Janet Fang | 12 June 2014

Source: Bielby, J. et al. Badger responses to small-scale culling may compromise targeted control of bovine tuberculosis, Proceedings of the National Academy of Sciences (2014). doi:10.1073/pnas.1401503111

Images: Volodymyr Burdiak, shutterstock (top) & Zoological Society of London (collared badger, below)

collared badger