What works? Counting badgers to evaluate lethal and nonlethal approaches to bovine TB control

Britain's biggest wildlife controversy, and its greatest animal health challenge, are one and the same: the control and eradication of bovine tuberculosis (TB), a disease which infects not only cattle, but also wildlife, including badgers. TB causes misery to farmers, and the British government's attempts to control it kill tens of thousands of cattle and badgers every year.

This project combines fieldwork with analysis and modelling to help tackle this longstanding problem. Government TB policy currently emphasises the large-scale culling of badgers. However, new research reveals marked variation in the effectiveness of this approach, with two areas recording declining cattle TB and a third showing a potential increase. Moreover, badger vaccination has been identified as a promising alternative to culling, with a recent policy review calling for a side-by-side trial comparing vaccination and culling. The effectiveness of both culling and vaccination are likely to depend upon the proportion of badgers that they reach. However, estimating the population reductions achieved by culling has proven challenging, and no attempts have been made to estimate the proportion of badgers reached by vaccination. Low vaccination coverage is likely to reduce the effectiveness of this management method, but low culling success can cause cattle TB to increase rather than decrease, potentially helping to explain the divergent outcomes of industry-led culling. The Random Encounter Method (REM) is a relatively new method for counting wild animals using camera traps, which offers the prospect of evaluating the proportion of badgers reached by both vaccination and culling programmes.

This project will explore the potential effectiveness of badger vaccination and culling by addressing four objectives:
1 Compare the Random Encounter Model (REM) with more conventional markrecapture methods of population estimation for badgers, by implementing both methods in vaccination areas at presumed high density (Cornwall) and low density (Derbyshire), where badgers are individually marked.
2 Use these population estimates to calculate the proportion of badgers reached by vaccination programmes, comparing especially those led by professional and volunteer teams.
3 Estimate the reductions in badger density achieved by industry-led culling, by comparing camera-trap-derived population estimates before and after culling, to inform interpretations of changing cattle TB incidence.
4 Combine these empirical estimates of vaccination and culling efficacy with existing dynamic and statistical models to explore the likely consequences of the two methods for TB management in badgers and cattle.