Badgers are one of only a handful of large native mammals left in the UK. They are protected by national and international law and are an important part of our biodiversity. One of the strongholds for the species is the south west of England where badger populations may have reached the natural carrying capacity, but in other areas, badgers are at much lower densities. Importantly, the UK has 25% of the global population of the Eurasian badger Meles meles. We therefore have an international responsibility to conserve the species, and that includes protecting the range of genetic variation within the UK population.
Bovine Tuberculosis (bTB) is caused by the bacterium Mycobacterium bovis, which affects a range of mammal species. Over the last 20 years the incidence of bTB in cattle has increased substantially; particularly in the south-west of England, the Midlands and Wales. This represents an economic burden on the taxpayer and the farming industry as infected herds are culled. It is a particularly unpleasant disease and is very distressing for farmers who will see entire herds culled if bovine TB is present.
Cattle become infected by other cattle through urine, slurry, contact etc, as well as by other infected mammals, including badgers. Defra say that 50% of herd breakdowns in low risk areas are due to purchase of infected cattle¹.
The role of badgers in the transmission and maintenance of bTB is difficult to accurately measure and all estimates have very broad confidence limits. The key source of information on the contribution from badgers within high-cattle-TB-incidence areas of England is the Randomised Badger Culling Trial (RBCT)². Modelling analysis of this data shows that roughly half of confirmed bTB herd breakdowns may be related to badgers²,3,4. However, the models also estimate that the average percentage of transmission to cattle herds that was badger-to-cattle was just 5.7%4 with the rest of the infection being from subsequent cattle-to-cattle transmission4,5. That is, a badger could infect a herd of cattle, but that infection then spreads from animal to animal, so that most cattle catch bTB from other cattle, not from badgers. Cattle can also spread the disease to badgers3.
Culling disrupts badger social structure, causing them to move around more frequently and over longer distances, potentially spreading disease (the ‘perturbation effect’). Because of this and the large role played by cattle to cattle transmission, the final RBCT report concluded “while badgers are clearly a source of cattle TB, careful evaluation of our own and others’ data indicates that badger culling can make no meaningful contribution to cattle TB control in Britain. Indeed, some policies under consideration are likely to make matters worse rather than better².” See evidence and reference for further details.
Despite this, since 2010, the Government has been piloting a controlled (licensed) shooting policy as a method of culling badgers in identified areas with the aim of delivering a reduction in confirmed new incidents of TB in cattle herds. The culls are being deployed in ‘high risk’ areas which have been identified by their high incidence of confirmed bovine TB in cattle. Licensing of a cull requires access to 70% of an area at least 100km2. This is to ensure that the target reduction of at least 70% of the badger population in that area is achieved. The cull must also be sustained annually for a minimum of 4 years. Natural England take into account conservation considerations for land within designated conservation areas e.g. Special Protected Areas and Sites of Special Scientific Interest.
 Bourne et al. (2007) ‘Bovine TB: The Scientific Evidence: Final report of the Independent Scientific Group on Cattle TB’ https://webarchive.nationalarchives.gov.uk/20081108133322/http://www.defra.gov.uk/animalh/tb/isg/pdf/final_report.pdf
 Godfrey et al. (2013) ‘A restatement of the natural science evidence base relevant to the control of bovine tuberculosis in Great Britain’ Proc R Soc B 280: 20131634 https://royalsocietypublishing.org/doi/full/10.1098/rspb.2013.1634
 Donnelly and Nouvellet (2013) The Contribution of Badgers to Confirmed Tuberculosis in Cattle in High-Incidence Areas in England. PLoS Currents: Outbreaks, available here: http://currents.plos.org/outbreaks/article/the-contribution-of-badger-to-cattle-tb-incidence-in-high-cattle-incidence-areas/
See our Evidence and References section for more information on the Government’s strategy on achieving bovine TB free status in England and the Licensing policy for culls.