In the UK, the Badger Cull has become a national news item, and has stimulated fierce public debate, campaigns, protests and petitions from both sides. Many impassioned articles have been written over the last few months and years, but in many cases, even reputable authors have been guilty of cherry-picking data to support their claim. Everybody seems to have an opinion on the UK badger cull, and this often obscures the real science that is being done to investigate this crucial social and economic issue.
A Little Background
For those of you who haven’t heard about it, the badger cull is a UK government policy aimed at reducing the incidence of bovine tuberculosis (Mycobacterium bovis) by reducing transmission rates from a suspected infection reservoir in the European badger (Meles meles). It has been implemented on and off since the early 1970s, despite legal protection of the badger since 1986.
The European badger (Meles meles) is a member of the family Mustelidae. It is a nocturnal, borrowing mammal that lives in close social groups. They are very fussy about keeping their burrow clean, making sure to use outdoor ‘latrines’ when they need to do their business. Although classified as carnivores, badgers are actually omnivorous, feeding on a variety of plant matter as well as small mammals and invertebrates, particularly earth worms and large insects. Badgers have a special place in British culture, appearing in folklore, fiction and poetry, being supported by legal as well as a great deal of public support, while also remaining the subjects of several sport hunting practices including ‘badger baiting’ and ‘digging’. All in all, the British feel very conflicted about the badger, in much the same way as we do about the fox.
Bovine tuberculosis is found in many badger populations in Britain but is particularly prevalent in good badger habitat in southwest England. In badgers, Mycobacterium seems to have a low mortality rate, allowing it to persist in badgers, and for infected individuals to remain infectious for long periods of time. Badgers have a low population growth rate, small litters and relatively slow sexual maturation, with populations often remaining stable at the carrying capacity of the environment. Populations therefore recover slowly from culling, although relatively rapid initial expansions are predicted. Based upon this alone, culling may not represent a viable long-term strategy for disease management.
Bovine Tuberculosis and UK Cattle
Tuberculosis is a chronic bacterial infection, which is usually asymptomatic in its early stages. In the UK and countries where TB eradication and testing procedures are in place, cases are usually caught before symptoms appear. However, if left untreated, bovine TB eventually develops into a fever and cough, accompanied by weight loss. Internally, TB is associated with lesions and abscesses particularly around the lymph nodes. In the UK, TB in cattle costs around £80 annually, both in proactive interventions (testing), reactive interventions (slaughter, follow-up testing), and government compensation to affected farmers. Around 50,000 herds (about 4.5 million cows) are tested and around 2000 new herd infections detected each year. Cattle TB is therefore a major economic concern; in 2012 28,000 cattle were slaughtered because of the disease and new herd infections have increased five-fold since 2006*.
* That statement may not actually be true. In 2014, Defra admitted that their published estimates of Bovine TB in UK cattle were incorrect and the real figures indicate a slight decrease in the occurrence since 2003 (see below). Sceptics have suggested this ‘accident’ may in fact have been a ploy used to strengthen the case for badger culling.
Bovine Tuberculosis in Wildlife and Cattle Globally
Mycobacterium bovishas one of the widest ranges of hosts of any complex pathogen, and is found on every continent except Antarctica. Although it is best known in cattle, wildlife reservoirs have been detected in many species including the African buffalo (Synerus caffer), Lechwe antelope (Kobus leche), wild boar (Sus scrofa), white-tailed deer (Odocoileus virginianus), elk (Cervus elaphus), and the brushtail possum (Thrichosurus vulpecula). The incidence of M. bovis in developed nations remains relatively low, but it is more of a concern in the developing world where transmission to humans may occur frequently. Importantly, across a variety of M. bovis hosts, it is common for a species to act as a reservoir host in one country but be only a spillover host in another. Habitat, climate, diet and behaviour are likely to contribute to the different roles of wildlife in M. bovis transmission to humans and livestock, but it may be difficult to generalise from the patterns observed in one region.
So, TB in cattle is definitely a bad thing. And badgers definitely have TB. But this information alone is insufficient to conclude that badger culling is the best response to tackle the problem. Lets see what the science says about badgers and bovine TB.
- Do Badgers Give Cattle TB?
- How is Transmission Occurring?
- Is Culling Effective?
The first case of bovine TB in badgers was reported in the 1970s, and recent estimates indicate approximately 15% – 20% of UK badgers are infected. However, relatively few cases in badgers ever become serious, with only about 1.5% of badgers showing severe symptoms. Direct evidence for transmission from badgers to cattle is still lacking, but a great deal of circumstantial evidence is stacking up. Badgers tend to carry the same strain of M. bovis as local infected cattle, implicating transmission between the two. However, this does not demonstrate causation, and cattle could just as easily be transmitting TB to badgers. And there is some anecdotal evidence that this may be the case. During the foot and mouth epidemic in 2001, there was a delay in removing TB infected cattle because of restrictions on livestock movement. During this time, badger infection rates increased, suggesting the infected cattle were responsible for transmitting to badgers.
The incidence of TB infections in closed herds has been cited as concrete evidence for transmission from badgers to cattle, however since the current bovine TB skin test is only 72% effective, herds could easily be harbouring infected animals without realising it. In the laboratory, experimental trials have successfully achieved badger-to-cattle transmission of M. bovis, although rather inefficiently. It therefore seems likely that transmission occurs in both directions, with both species possibly acting as a reservoir for the other.
It is important to note that despite a co-occurence of cattle, badgers and bovine TB across much of temperate Eurasia, only in the UK and the Republic of Ireland have they been linked, suggesting a very specific mode of transmission. The transmission of M. bovis between species may be strongly dependent on abiotic variables such as climate, habitat and population demography.
There are two possible modes of transmission – direct aerosol inhalation, which requires very close proximity, and indirect contact, usually with excretions. Direct contact was long considered unlikely, and studies largely focussed on the source of indirect infection. Cattle may pick up the infection by grazing badger latrines – evidence suggests that although they prefer to avoid them, cattle will graze at latrine sites if food availability decreases. Further, they do not attempt to avoid disused latrines, which could harbour active TB bacilli for up to two years. Indirect infection may also occur if badgers steal food from troughs, or enter farm buildings (particularly feed stores). Surveillance has revealed that this is a regular occurrence, and feed stores often become a badger party at night. Research suggests that feed stores may be a particularly important source of food for badgers during the dry summer months when their usual diet of earthworms becomes more scarce.
As well as indirect contact, direct contact occurs more often than previously thought. M. bovis infection is most effective through aerosol transmission, consistent with pathology reports which indicate a respiratory mode of infection. A paper published in Nature this year has revealed new insights into how bovine TB is spreading through our cattle. Using a mechanistic computer simulation, the authors modelled the real spread of bovine TB between 130,000 cattle farms in Great Britain between 1996 and 2011. The considered several possible modes of transmission, including direct contact between infected cattle, animal movement between farms and transmission through an environmental reservoir (e.g. badgers). Their findings revealed that the most common source of new infections in previously uninfected farms was the movement of animals between herds. Relatively few farms (2%) were responsible for infecting many others (>10), while the majority of infected farms (90%) never spread any infections outside of their own herd. This is consistent with the recently revealed trend indicating that increased biosecurity regulations and more rigorous testing have already begun to reduce the rates of bovine TB in the UK. It seems the badger may have been falsely accused!
Understanding the behaviour and ecology of cattle, badgers and the TB bacterium itself can illuminate possible explanations for the high transmission rate. Data from tracking studies have shown that badgers actually come into contact with cattle more frequently than they do other badger groups, and individual cattle that frequently come into contact with badgers are also highly mobile within their own herd. Together this is likely to generate high transmission rates. Furthermore, it has been shown that infection with bovine TB alters behaviour in badgers, increasing home-range size by 50% (producing more overlap between territories) and increasing the distance of foraging trips by 65%. Thus, infected badgers seem to be more mobile and more likely to encounter other badgers, and a larger foraging range may increase their chances of encountering food laden farm-buildings.
Culls currently come in two main forms: proactive and reactive. Proactive culling is implemented irrespective of incidents of cattle TB and is aimed at generally reducing badger numbers in areas of cattle farming. By contrast, reactive or localised culling is implemented only in badger populations occurring in close proximity to infected farms. Unfortunately, a selective culling strategy that specifically targets infected badgers is not possible, as a reliable diagnostic test is not available. Culling definitely kills badgers – it has been shown to reduce badger numbers, with proactive strategies being more effective in this.
In Ireland, badger culling appears to have been highly effective, with a 50% reduction in bovine TB cases since 2000. This is thought to be the result of a 25-year reactive culling program that costs nearly £3 million annually, and utilises a more effective method for culling (snare and shoot). However, Irish badger populations are smaller and less dense, and differ in diet and habitat, which may influence contact and TB transmission between Irish cattle and badgers.
In the UK, culling does not appear to directly link to reductions in cattle TB. A year after the first culls in the RBCT, plots subjected to reactive culling experienced an average increase in herd breakdowns of 27% compared to un-culled areas. After five years of culling this had improved slightly, but reactive culling still lead to a 20% increase in herd breakdowns. Reactive culling, is clearly not an option. Proactive culling faired a little better; within the culled area, proactive culling reduced herd breakdowns by 23%, equivalent to around 116 herd breakdowns prevented. However, the boundary of the cull zone experienced a rather different effect. Here, cattle TB increased. Across the 10 proactively culled plots, there were an estimated 102 extra herd breakdowns than in the margins of un-culled regions. The net benefit of even proactive culling, therefore, is extremely minimal, amounting to just 14 spared herds achieved from a huge effort.
In 2007, the Independent Scientific Group on Cattle TB noted in their final report on the RBCT that “reactive culling increased, rather than reduced, the incidence of TB in cattle, making this unacceptable as a future policy option” and although “proactive culling reduced TB incidence in cattle in culled areas […] this beneficial effect on cattle breakdowns was offset by an increased incidence of the disease in surrounding un-culled areas”
How can killing badgers increase TB in cattle? The RBCT, along with several other studies, have now fairly conclusively demonstrated a social perturbation effect that is responsible for this bizarre result. Badgers are fiercely territorial and maintain relatively small, well defined territories. In natural conditions, badger social groups rarely come into contact, and TB infections are highly localised. However, culling, and the massive disturbance and trauma it causes to the population, causes badgers to move around more and come into contact with other badgers a lot more, presumably increasing badger-to-badger transmission rates. Furthermore, this effect is seen not just in the culling area, but within a buffer zone around it. Home range size has been found to increase with proximity to a culling area, as does the overlap between home ranges of different. Increased ranging behaviour may also represent a strategy of male badgers to find new mates; this may be particularly problematic because males have previously been found to be more susceptible to TB and to be more exploratory when infected. This perturbation effect may well result from culling, however studies have shown higher infection rates in smaller social groups and at lower population densities, suggesting it may also reflect a more enduring aspect of their social behaviour. Either way, fewer badgers seems to equal more TB.
One way to improve the effectiveness of the cull, therefore, would be to increase the size of culling areas – as the size of the culled area increases, it’s importance increases relative to the detrimental effect of the border effect. According to Defra, 5-years of culling in an area of 150km2 would lead to a 16% reduction in cattle TB incidence in the local area. In 2010, Defra claimed that “the results of this trial [RBCT] demonstrate that badger culling, done on a sufficient scale, in a widespread, coordinated, and efficient way, and over a sustained period of time, would reduce the incidence of bovine TB in cattle in high incidence areas”. While this might seem like a pretty radical interpretation of the data, it is also exactly what the 2013 trials are not. The trials are not being performed at a “sufficient scale”, or in a “widespread way”, or “over a sustained period of time”. So we shouldn’t really expect them to “reduce the incidence of bovine TB in cattle”.
Another problem for culls is that a total eradication of the badger is unacceptable; the badger is a protected species and it’s local extinction would violate the Bern Convention on the Conservation of European Wildlife and Natural Habitats. Cull too many badgers and you risk local extinction. Cull too few, and TB gets worse as the remaining badgers run around like crazy (because you’ve been shooting at their family) and infect your cattle. It is crucial, therefore, that any cull achieves it’s targets in terms of badger deaths, a feat that isn’t as easy as you might think. An effective badger cull involves the collective efforts of hundreds of dedicated and highly skilled people, amounting to hundreds of nights work across many years.
It has been estimated that uncertainty in both estimates of badger population sizes and culling effectiveness means that a licence to cull 344 badgers could remove anywhere between 51% and 100% of the resident badger population. Outcomes at either of these extremes would be very dangerous, either resulting in increased TB transmission or local extinction of the badger. Uncertainty could be reduced by surveying after culls, but this would further increase the costs.
In their recent model, Brooks-Pollock and colleagues investigated how the implementation of different possible management strategies might have influenced bovine TB in the UK between 2006 and 2011. Of ten possible measures they tested, only 3 were able to stop annual increases in bovine TB. Culling was not one of these. Even reducing the transmission through badgers by 50% would not reduce bovine TB, and the authors concluded that control measures focussed on a single transmission route were unlikely to be effective.
The History of Badger Culling in the UK
The British response to the bovine TB problem has been to regularly test cattle, slaughter any infected cattle and temporarily restrict movement of infected herds (a strategy that has been effective in other countries), in addition to culling of badgers. Badger culls have occurred since 1973 and although they appeared initially to be effective in reducing bovine TB, it’s efficacy began to be questioned in the 1990s and recently, the incidence of TB in cattle has increased again*.
The Randomised Badger Culling Trial
In 1996, Lord Krebs, commissioned by the government to review the evidence for the effectiveness of badger culling, deemed it inconclusive. The randomised badger culling trial (RBCT) was commissioned, and the Independent Scientific Group on Cattle TB (ISGCTB) was formed, at a cost to the tax payer of about £50 million. The ISGCTB initiated a range of research projects working on diagnosis, pathogenesis, disease dynamics and TB control in cattle and badgers, as well as overseeing the RBCT. This trial aimed to apply rigorous scientific testing to the issue, including randomised trials of two alternate culling methods, compared to an alternative of no culling at all, repeated in 10 triplets of test plots across the UK, with long-term follow-up to monitor the effects.
This study concluded in 2007 that, far from reducing TB in cattle, some forms of culling actually increased the spread, and that “badger culling cannot meaningfully contribute to the future of cattle TB in Britain”. However, since then, the results of this study have been criticised by some scientists, and the debate rages on. What is particularly frustrating is that both sides of the argument seem to see the results of the RBCT (see below) as validation of their point of view – it seems we are £50 million down and no further forward.
Badger Culling Pilot
In 2011, The Department for Environment, Food and Rural Affairs (Defra) announced a management policy to allow culling to be carried out by farmers and landowners in the worst affected regions. This policy would begin with pilot studies in West Gloucestershire and West Somerset, conducted by the ISGCTB, to test whether a 70% reduction in badger population (amounting to around 5000 badgers) within a 6-week cull period was feasible using a controlled shooting method. This method involves shooting free-ranging badgers, rather than the more expensive, traditional method of trapping them first. It has been criticised for being inhumane, although Defra claims that the trials themselves will be used to assess the humaneness of the controlled shooting approach. (One of their methods for assessing humanness is reportedly to listen for the screams of dying badgers. Euck).
In October 2012, the pilots were postponed for a year and they began again in August 2013. However, results were only ever collected from about a sixth of each pilot area, meaning that around 4200 badgers were killed without yielding any evidence. Before they even began, Lord Kreb warned that the pilot “would not yield any useful information” because of it’s small scale, a point which even farming minister David Heath accepted. And yet the trials went ahead anyway.
Early reports indicated that the cull was not going according to plan. Protestors disrupted a few culls, using torch lights and loud noises to scare off badgers and some were arrested. Wounded badger patrols came to the aid of injured animals, and reports of suffering came in thick and fast. A third of the way through the cull, as few as 100 badgers were reported to have been killed in Somerset, falling seriously short of the area target of 2000. By the end of the six-week cull, the expert panel found that cull teams had only managed to kill around 30% – 40% of badgers, well short of the 70% needed to yield a benefit, so the culls were extended. Even after a further three to five weeks of culling, the final estimates rose to just 30% – 55% of badgers killed in pilot areas. This equates to around 900 badgers killed in each pilot area.
Not only was the 2013 cull ineffective in it’s aims of culling 70% of the badger population in culling areas, it also failed to meet animal welfare targets. Between 7 and 23% of badgers took more than five minutes to die after being shot, and were assumed to have experienced “marked pain”. This single pilot cost the UK tax payers around 7 million pounds, caused suffering to at least 1800 badgers, and failed to achieve any of it’s goals. According to the former environment secretary Owen Paterson, the 2013 cull pilots failed to achieve their goals because “the badgers moved the goalposts”
Despite all of this, the UK government has decided to continue culling trials in the same areas this year. Perhaps if they can improve effectiveness and humaneness, culling might be extended to more areas in 2015. Otherwise, the policy will need rethinking. Or so the government claim. But, trained marksmen are now back in the British countryside, and this cull is even less likely to yield meaningful data than the last. To save money, the government has abandoned previous assessment measures such as genetic fingerprinting (to estimate true badger population sizes, which is notoriously difficult because they’re shy) and independent scientific observations of badger suffering (to assess humaneness). Instead, they plan to just ask the marksmen whether the cull was effective and humane or not. This is despite the fact that data collected by marksmen last year was deemed so unreliable it wasn’t even considered in the independent panel’s assessment. It seems, to the casual observer, as though the government has deliberately designed a study that cannot fail to provide the answer they want.
Further, these culls are also less likely to be effective in quelling Bovine TB. This year’s targets aim for just under 1000 badgers to be culled across the two pilot areas. This is fewer than last year and the culls are starting later in the year this time around, even though killing badgers becomes increasingly difficult as the weather cools, as they tend to spend more time underground. Even if targets are met, the pilots may well fall short of reaching the 70% culling target across two years of culling.
The Lies Defra Tell
This year, Defra admitted that due to an ‘IT glitch’, their published figures about the shocking increases in bovine TB in UK cattle were actually a huge exaggeration. In fact, it was such a big exaggeration that they reported an 18% increase in cases of infected herds since 2003, rather than the reality, a 3.5% decrease. The truth is that in 2013, 13% fewer cattle were slaughtered because of bovine TB than in 2003, making the case of the badger cull even weaker. It seems that recent increases in testing and biosecurity measures, largely imposed by EU legislation, has been effective in reducing the Bovine TB problem in the UK. It is still a major issue to the livelihoods of many farmers, and a significant drain on the economy, but the situation at least does appear to be getting better.
So, it seems the government has stacked the deck. Unable to get the answers they wanted from independent scientific studies, or from expert panels monitoring culling trials, they’ve opted for a review process that is almost certain to give them the answer they want – that culling should continue. The UK government continues to refer to it’s policy of badger culling as “science-led”, in reality, it is anything but.
So, it seems there may be a fairly minor benefit in terms of reduced cattle TB from culling almost three-quarters of the wild badgers in areas of high TB-prevalence. This benefit might start to exceed the costs, as long as culling is maintained over time and over as large an area as possible. Right. Ok. But how much does that cost?
- Is culling economically viable?
According to the ISGCTB, the UK government at present spends about £20 million each year testing 50,000 herds for TB (4.5 million cattle), and a further £60 million is spent on dealing with the 2000 or so herds that test positive (slaughter, further testing). Reactive culling an area of 100km2 in a bovine TB hotspot is expected to increase herd breakdowns by 22% (which is obviously worse than useless!). Conversely, proactive culling would reduce herd breakdowns by about 25%, equating to a saving of about £26,000 a year. Somehow, Defra estimate that culling a single 350km2 area could save the government £2.5 million across 10 years, although I can’t find any independent verification of these sums, and other estimates disagree.
Further, all of this ignores the border effects! When we consider the increased incidence of bovine TB in areas bordering cull-zones, the net reduction in herd breakdowns is actually just 1.4% per year, offering an economic benefit of around £8000 a year. Thus, it looks as though the overall economic effect of Badger culling is negative. One estimate suggests that the proactive culling necessary to achieve a 70% population reduction would cost about 5 times as much as it saves. So why is the UK government still so keen on the idea?
According to Defra, each year badger culling would cost £2,500 per km2 for cage-trapping and shooting, or £300 per km2 for shooting free-ranging badgers, giving an average cost of £1,000 per km2 per year for a mixture of these two approaches. That gives an annual bill of between £75,000 and £285,000 a year. However, the pilot culls in 2013 along cost £7 million – that’s £4000 per dead badger, so it’s hard to see how this all adds up. Based on these figures, a four-year cull in Gloucester and Somerset would cost around £20 million, but give savings of just £2.5 million.
Although the overall effect on the UK economy might be negative, individual farmers who succeed in reducing herd breakdowns on their own farms would gain an enormous benefit. A confirmed herd breakdown about £30,000, of which the government pays about two thirds, leaving the farmer with a £10,000 bill. Is this whole political issue just a very simple case of the tragedy of the commons? Are individual interests winning out over the needs of the whole country?
From the scientific evidence, it seems that culling badgers is not an effective mechanism for controlling bovine TB. Certainly, it is does not appear to be an economically viable one. So what alternatives are there? There have been a number of suggested strategies to manage the bovine TB problem, many of which have been used in other countries.
- Cattle Control Measures
- Testing and Slaughter
Since 1994 £43 million has been spent developing an oral vaccine for badgers and a vaccine for cattle. Computer simulations suggest that a vaccination program would be sufficient to control the spread of bovine TB in the UK. However, a cattle vaccine remains a decade away, and current EU legislation would not allow cattle to be vaccinated against TB, anyway. There is a badger injection available but it requires trapping, and is not 100% effective. Research continues in developing an oral vaccination for badgers. Environment secretary, Owen Paterson said in August 2013 “If we had a workable vaccine we would use it… a vaccine is at least 10 years off”. However, he also noted that a vaccine would not help the large numbers of infected individuals already present in the population. This isn’t strictly true; the current injected vaccine actually works by reducing the effect of the M. bovis infection on badgers, reducing the number of legions and making them less ill and less infectious. Whether an oral vaccine would prevent infection or simply reduce the severity of infection isn’t clear, however it would potentially be simple and cheap to implement on a large scale.
In their 2007 final report, the Independent Scientific Group on Cattle TB concluded that improved cattle control measures represented the best option for the control of bovine TB, and that modelling indicated these measures would “reverse the trend in cattle disease incidence” without the need for culling. Based on the known ecology and behaviour of badgers, a number of simple strategies could be employed to reduce contact, such as moving cattle between grazed areas more frequently. Removing supplementary feed from pastures, particularly those close to badger setts, could also help. Simply making the feed troughs higher is no good as badgers are excellent climbers. Defra advice also suggests that farmers should try to prevent badger access to farm buildings by, well, putting in a solid door. Duh. Despite clear evidence that this can and does reduce badger access, only 14% of TB-affected farms have adopted these measures.
Electric fences can also be used to deter badgers effectively. Although excluding badgers from farms causes them to forager further a field, unlike culling, it does not cause them to break territorial boundaries and so should not increase badger-badger transmission rates. Excluding cattle from areas of higher risk could also be effective. Badger setts tend to occur in localised clusters, so preventing cattle access to just a small area of potentially infective land could have a big impact
In their model, Brooks-Pollock found that the most effective strategy for reducing bovine TB was to cull the entire herd of cattle in response to a positive test for bovine TB. Whilst initially a costly move, requiring a 20-fold increase in cattle slaughter in the first year, in simulations it rapidly brought the epidemic under control. Further, once the intial culls were complete, in the long-run fewer slaughters would be required as fewer cattle were infected.
The Last Word
What is the future of the badger cull? In an ideal world, government policy would be made on the basis of sound scientific research, and designed to give the best possible outcome for all parties. Unfortunately, this is not the case, and the badger cull has no end in sight. It is hard to see what would change the current direction of policy regarding bovine TB, other than, perhaps, a change of opinion on the part of the farmers. But if it is more financially beneficial for any single farmer to pay for a badger cull than to pay for the slaughter of their entire herd, then we may be stuck in a case of a tragedy of the commons. Evolutionary theory suggests that it is extremely difficult to resolve a situation to the collective benefit when individual benefits for not cooperating are greater than the shared benefits of cooperating.
Want to Know More?
- Anderson and Trewhella (1984) Population dynamics of the badger (Meles meles) and the epidemiology of bovine tuberculosis (Mycobacterium bovis). Philosophical Transactions of the Royal Society, London B: Biological Sciences 310: 327 – 381
- Hutchings and Harris (1997) Effects of farm management practices on cattle grazing behaviour and the potential for transmission of bovine tuberculosis from badgers to cattle. The Veterinary Journal 153: 149 – 162
- Donnelly et al(2003) Impact of localized badger culling on tuberculosis incidence in British cattle. Letters to Nature 426: 834 – 837
- Roper, Garnett and Delahay (2003) Visits to farm buildings and cattle troughs by badgers (Meles meles): a potential route for transmission of bovine tuberculosis (Mycobacterium bovis) between badgers and cattle. Cattle Practice, 11: 9-12.
- Garnett, Delahey and Roper (2005) Ranging behaviour of European badgers (Meles meles) in relation to bovine tuberculosis (Mycobacterium bovis) infection. Applied Animal Behaviour Science 94: 331 – 340
- Woodroffe et al (2006a) Effects of culling on badger Meles meles spatial organization: implications for the control of bovine tuberculosis. Journal of Applied Ecology, 43: 1–10
- Woodroffe et al (2006b) Culling and cattle controls influence tuberculosis risk for badgers. PNAS 103(40): 14713–14717
- Independent Scientific Group on Cattle TB (2007) Final report of the Independent Scientific Group on Cattle TB (London: Department of the Environment and Rural Affairs)
- Böhm et al (2008) The spatial distribution of badgers, setts and latrines: the risk for intra-specific and badger-livestock disease transmission. Ecography 31: 525-537
- Böhm, Hutchings and White (2009) Contact Networks in a Wildlife-Livestock Host Community: Identifying High-Risk Individuals in the Transmission of Bovine TB among Badgers and Cattle. PLoS One 4(4) e5016
- Humblet, Boschiroli and Saegerman (2009) Classification of worldwide bovine tuberculosis risk factors in cattle: a stratified approach. Veterinary Research 40: 50
- Woodroffe et al (2009a) Bovine Tuberculosis in Cattle and Badgers in Localized Culling Areas. Journal of Wildlife Diseases, 45(1): 128–143
- Woodroffe et al (2009b) Social group size affects Mycobacterium bovis infection in European badgers (Meles meles). Journal of Animal Ecology, 78: 818–827
- Defra (2010) Bovine Tuberculosis: The Government’s approach to tackling the disease and consultation on a badger control policy.
- Allen, Skuce and McDowell (2011). Bovine TB: a review of badger-to-cattle transmission.
- Cassidy (2012) Vermin, Victims and Disease: UK Framings of Badgers In and Beyond the Bovine TB Controversy. Sociologia Ruralis 52(2): 192 – 214
- Defra (2012) Badger culling pilots: Independent Expert Panel. Monitoring the effectiveness of badger population reduction by controlled shooting.
- Donnelley and Woodroffe (2012) Reduce uncertainty in UK badger culling. Nature Correspondance 485: 582
- Gortázar et al (2012) The status of tuberculosis in European wild animals. Mammal Review 42(3): 193 – 206
- Defra (2013a) Animal Diseases: Badger Control – culling of badgers.
- McInerney Economic Aspects of Badger Culling
- BBC News (2013) Badger cull begins in Somerset in attempt to tackle TB.
- Guardian (2013) Badger cull: government could be forced to take direct control of pilot.
- Defra (2013b) Badger cull – piloting controls on bovine TB.
- Defra (2013c) Badger culling will have a significant impact on bovine TB.
- Bovine Tuberculosis Statistics and Costs (2013)
- The Conversation (2014)British government on the badger cull: ask scientists for help then ignore them
- Brooks-Pollock, Roberts & Keeling (2014)A dynamic model of bovine tuberculosis spread and control in Great Britain
- Guardian (2014) Badger cull starts in Somerset and Gloucestershire
- Animal Ecology in Focus (2014) Name: UK government. Animal ecology test score: 0
- The Independent (2014) Government releases figures showing badger cull case was exaggerated by flawed bovine TB statistics
- Politics (2014) Comment: The horrible truth about the badger cull
Featured image used under a creative commons licence from Wikimedia commons. Image by Ecology of Commanster.