Badgers and bovine tuberculosis (bTB) Questions and Answers

Badger cub photo by Elliot NeepBadgers Q&A

We have created this page to answer the questions people have about this complex issue as best as we can with information from across The Wildlife Trusts.

What is bovine TB?

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; not just in the south-west of England but also in Wales and the Midlands. This represents an economic burden on the taxpayer and the farming industry as infected cattle are culled.

Do badgers infect cattle with bTB?

The first badger to be found infected with bTB was a road casualty animal in Gloucestershire in 1971. The scientific evidence suggests that cattle can get bTB from direct or indirect contact with badgers, or other wild animals. It is not known what proportion of bTB in cattle arises from badgers but the most recent study suggests that around 50% of outbreaks are related to badgers. However, the proportion of outbreaks caused directly by badgers is much lower (5.7%), with these initial infections amplified by cattle-to-cattle transmission. There is evidence of cattle to badger transmission in parts of England to which cattle were moved from bTB infected areas during re-stocking following foot and mouth disease.

Do other animals such as deer also get bTB?

Yes. Mycobacterium bovis can also infect and cause bTB in deer, goats, pigs, camelids (llamas and alpacas), dogs and cats, as well as many other mammals.

Do badgers die of TB?

Some badgers become infected with bTB but rarely die of the disease. The planned pilots aim to cull 70% of the badgers in these areas and most of those killed will not be infected with bTB. On balance most badgers will live for around 5 or 6 years in the wild. They rarely die of TB.

What is the current conservation status of the badger in the UK?

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.

Badgers and their setts are protected under the Protection of Badgers Act 1992, which makes it illegal to kill, injure or take badgers or to interfere with a badger sett. Badgers are also protected by the Convention on the Conservation of European Wildlife and Natural Habitats (known as the Bern Convention).

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.
 

Isn’t the population out of control because there are no natural predators for badgers?

The UK badger population is estimated to be around 400,000 although there are no up to date figures. The ecology and behaviour of badgers makes them very difficult to count and so the only national surveys that have been undertaken have estimated the number of setts, rather than the number of badgers.

There have only been three national badger sett surveys in Great Britain: the first was undertaken from 1985-88, then the second in 1994-97. Based on the results of these surveys, it was estimated that the number of badger social groups had risen by 24%, from 42,000 in the 1980s to 50,000 in the 1990s, and that the number of badgers had increased by 77%, from approximately 250,000 to 400,000. This increase was due mainly to increased family size, followed by colonisation of new unoccupied areas as the badger population recovered from past persecution (Wilson et al (1997) Changes in the British badger population).

The latest national sett survey was undertaken between November 2011 and March 2013. It estimated that there were 71,600 social groups across England and Wales, with 64,000 of these in England. This represents a 103% increase in the number of social groups in England since the 1980s (Judge et al (2013) Density and abundance of badger social groups in England and Wales 2011-2013). The number of badgers per social group is highly variable, so it's not yet possible to estimate the total number of badgers in England. Assessment of the variation in the number of badgers per social group is ongoing.

The population density of badgers is limited by the environment in which they live. The pastures, meadows, hedgerows and woodlands of England and Wales create rich habitat with abundant food and shelter. One of the strongholds for the species is the south west of England. Here badger populations may have reached the natural carrying capacity, but in other areas, badgers are at much lower densities.

Badgers in the UK do not have any natural predators, though elsewhere in Europe cubs may be taken by mammals such as bears and wolves. The main ‘predator’ for the badger in the UK is currently the car, with 50,000 badgers killed on our roads every year.
 

What is the impact of a badger cull on other wildlife species?

The final report of the Independent Scientific Group on Cattle TB (2007) states that:
‘In addition to its effects on badgers themselves, proactive culling in particular had impacts on other wildlife species. Numbers of foxes (Vulpes vulpes) increased in proactive areas, in comparison with survey-only areas and, perhaps as a result, numbers of hares (Lepus europaeus) declined (Trewby et al., in review). Before culling, hedgehogs (Erinaceus europaeus) were rare in parts of RBCT areas where badgers were abundant (Young et al., 2006), and badger culling increased their numbers (G. Wilson, personal communication).’

Who will pay for the culls and how much will they cost?

The badger control policy is based on a cost-sharing approach with the farming industry. The industry is responsible for the operational costs of delivering culling and Defra bears the costs of licensing, monitoring and policing the policy. Defra estimated the cost of various options:

Licensing: £377,000 per cull area
Co-ordination: £20,000/area/year
Culling using cage trapping: £2,500/km2/year, for 4 years
Culling using controlled shooting: £300/km2/year, for 4 years
Culling using a combination of methods: £1,000/km2/year, for 4 years
Vaccination: £2,250/km2/year, for 4 years
Monitoring: £737,000 per area
Policing: £500,000 per area/year, for 4 years

However, the total estimated cost of the two pilot culls in 2013 was £7 million, with policing alone costing £2.6 million - far exceeding anticipated figures.

What will happen after the pilot culls?

An independent panel of experts is assessing the safety, humaneness and effectiveness of the pilot culls and their final report is expected in February.

If Ministers decide to extend the cull following the pilots, a maximum of ten licences will be granted to start each year. The exact timings of the process following the original pilots are unclear. However, the reporting process will need to be complete in order to allow time for new cull areas to be developed if the policy is to be rolled out.

Are The Wildlife Trusts allowing culling on their land?

No. None of the 47 Wildlife Trusts will allow culling to take place on their land.

What is the perturbation effect?

Badgers typically live in social groups of four to seven animals with defined territorial boundaries. In a stable badger population, there is limited movement from one area to another. As a result, badger setts harbouring high levels of bTB infection tend to remain relatively isolated. Removing badgers from cull areas opens up the territory, allowing badgers to come in from the surrounding areas. Badger movements around and beyond the infected area increase. Immigrant badgers pick up the infection from abandoned setts and unculled infected animals. Badger to badger transmission increases along with the likelihood of badger to cattle transmission. Because the population is still lower than the carrying capacity of the total area, badgers move around much more than they did before the cull. The movement distributes the original infection over a wider area. This is known as the 'perturbation effect'.


Can a cull be designed to avoid the perturbation effect?

The Independent Scientific Group on Cattle TB concluded in its final report (2007) that it was “unable to conceive of a system of culling, other than the systematic elimination, or virtual elimination, of badgers over very extensive areas, that would avoid the serious adverse consequences of perturbation”.

Why do The Wildlife Trusts think six weeks too long for a cull?

The majority of culling operations during the RBCT occurred over a period of eight to eleven consecutive nights. On four occasions culling took place sector by sector over several months but this method was associated with a greater rise in TB prevalence in badgers.

In the Republic of Ireland is there a research study that proves that badger culling works?

A large scale trial of the effects of badger culling on cattle TB incidence has been undertaken in the Republic of Ireland known as the Four Areas Trial. The outcomes cannot be directly compared with the RBCT due to differences in methodology including use of snares and geographical boundaries such as coastline and rivers.

What about other countries? Haven’t they tackled the problem in the wildlife reservoir?

Quotes about potential TB control in other countries often overlook key facts. In New Zealand, possums are culled to deal with bovine TB but, unlike badgers, they are non-native mammals and are also culled for conservation reasons to protect native bird species. This is therefore not a justified comparison to the situation in England. Moreover, in Australia and New Zealand there are much more rigorous programmes of local cattle herd depopulation, movement restriction and reintroduction when there has been a breakdown. This has not been accepted as part of bTB control in England.

What is the policy of the Welsh Government?

The Welsh Government announced in March 2012 it would undertake a badger vaccination project within the TB Intensive Action Area (IAA) in west Wales as part of its bTB eradication programme. According to the Welsh Government’s report of the project’s first year, a total of 1,424 badgers were vaccinated by the end of November 2012 by ten teams of two field operatives at a cost of £943,000. None showed visible signs of disease.


What are the potential benefits of cattle vaccination?

Cattle vaccination offers the best long-term way to reduce bTB in the cattle population. A sustained vaccination programme would be required with annual re-vaccination.

Is a cattle vaccine available?

The research and testing of a vaccine has been completed and also trialled in Ethiopia, but it is not yet technically called a vaccine in this country as it has to be accredited. However, accreditation for the European market cannot be progressed whilst an EU ban remains in place on the use of such a vaccine.

What changes are needed to allow a cattle vaccine?

Vaccination of cattle against bTB is currently prohibited by EU legislation, principally because BCG vaccination of cattle can interfere with the tuberculin skin test which is the recognised primary diagnostic test for TB in cattle. A test called a DIVA (see below) test could help resolve this issue.

What is a DIVA test?

The Animal Health and Veterinary Laboratories Agency is developing a test to differentiate infected from vaccinated animals - the Differentiating Infected and Vaccinated Animated (DIVA) skin test. This test would be used alongside the tuberculin skin test to confirm whether a skin test positive result is caused by vaccination or TB infection.

Why vaccinate badgers?

The aim of badger vaccination is to reduce transmission of bTB between badgers and between badgers and cattle. It reduces the severity of the disease, the shedding of bacteria from infected individual badgers and therefore the disease’s prevalence in badger populations.

Is it true that there are no benefits before five years in a vaccination programme?

No. Research has shown that vaccination of individual captive badgers reduced the progression, severity and excretion of bTB. Protection and benefits at the population level take time to achieve, with longer vaccinating programmes being more beneficial than shorter ones.

How can improved biosecurity measures help?

Contact between cattle and badgers or their excretions may pose a risk of infection and improving biosecurity on farms can reduce this risk. The main transmission route between badgers and cattle has not yet been proven. Studies indicate direct contact between grazing cattle and badgers seems infrequent but transmission may occur via contaminated pasture or around farm buildings. Best practice videos and leaflets are available from the Defra website along with the following advice:

• Keep badgers away from stored cattle feed: badgers infected with TB can contaminate feed.
• Make your farmyard less attractive to badgers: badgers are likely to be attracted to accessible feed and may spread disease to cattle.
• Be aware of main badger latrines and active setts at pasture: where possible keep cattle away from these high-risk areas.
• Keep cattle away from neighbouring cattle herds: disease can spread between cattle.
• Protect your herd: source bought in stock carefully and adhere to isolation procedures for any inconclusive or reactor animals.

A research study by the Food and Environment Research Agency (Fera) concluded that simple exclusion measures are 100% effective in preventing badgers entering farm buildings when deployed properly. The badger exclusion measures were individually tailored to fit the requirements of each farm and sought to secure every potential entrance point on each selected facility.

If The Wildlife Trusts support the killing of species such as ruddy ducks and American mink, why do they oppose the cull of badgers?

Controlling some non-native species can be necessary sometimes where they are proven to threaten the conservation status of native wildlife. We only support the killing of wild animals when a strong scientific case has been made for the impacts and where it would be effective and humane. We oppose the large scale culling of native mammals.