FAQs: badgers and bovine TB
Why isn't the badger cull an effective way to halt the spread of bovine TB in cattle?
The Randomised Badger Culling Trial (RBCT), also known as the Krebs trial, ran from 1998 to 2005 and was funded by the Government. This trial, which compared the effects of proactive, reactive and no culling across ten sets of sites in England, came to two main conclusions:
"First, 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 better.
"Second, weaknesses in cattle testing regimes mean that cattle themselves contribute significantly to the persistence and spread of disease in all areas where TB occurs, and in some parts of Britain are likely to be the main source of infection. Scientific findings indicate that the rising incidence of disease can be reversed and geographical spread contained, by the rigid application of cattle-based control measures alone."
How could a badger cull make the bovine TB problem worse?
Badgers typically live in social groups of four to seven animals with defined territorial boundaries. Culling disrupts the organisation of these social groups, causing surviving badgers to range more widely than normal and increasing the risks of disease transmission.
This is known as the 'perturbation effect' and you can download The Wildlife Trust leaflet which explains more about this
Can improved biosecurity reduce the risk of infection?
Yes. 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.
How can farmers implement better biosecurity?
DEFRA recommend taking the following action:
- 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.
Is the badger population ‘out of control?’
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.
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 on-going.
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.
Do badgers cause serious declines in populations of ground nesting birds?
A number of studies have been carried out on this subject in recent years - below are some of their key findings:
Hounsome, T. and Delahay, R. (2005) Birds in the diet of the Eurasian badger: a review and meta-analysis Mammal review 35 199 - 209
This study reviewed 110 studies of badger diet. Birds were present in the majority but at low levels of occurrence (6%). Most reports involve game or ground nesting birds and do involve predation of eggs or chicks. They can potentially be locally significant predators during the breeding season but are opportunist feeders.
Gibbons et al (2007) RSPB Research Report No. 23:56
This study found that badgers don't constitute a threat to any bird species at national or international level and are not economically significant predators of game birds. http://www.wildlifetrusts.org/sites/default/files/rspb-predator-report_1.pdf