In part two of our series about badger culls in England, Wildlife Matters delves into the pivotal scientific research conducted by British government scientists, known as the RBCT— The Randomised Badger Cull Trials. This study, still the most reliable peer-reviewed science on badger culls in the world today, holds significant implications for our understanding of badger culling.
If you have researched the UK’s Badger Culls, you have encountered the Randomised Badger Cull Trial, more commonly referred to as RBCT. But what exactly is the RBCT, and why should anyone care?
The Randomised Badger Culling Trial, or RBCT, was conducted over nearly ten years (1998-2007) and cost taxpayers approximately £50 million.
The goal of the RBCT was to quantify the effects of badger culling on bovine tuberculosis in cattle herds and determine how such strategies could reduce the chance of a herd breakdown due to TB. An independent Scientific Group (ISG) monitored the RBCT trials.
It started with the Krebs Review on Bovine TB in Cattle and Badgers in 1997. This review stated that there was ‘compelling’ evidence that badgers played a role in transmitting the disease to cattle. This means that badgers, as carriers of bovine tuberculosis, can potentially infect cattle herds. However, the data available at the time made it difficult to develop a control policy based on badger culling. The review recommended conducting a large-scale field trial to determine the effectiveness of badger culling in reducing the incidence of TB in cattle and minimizing risk.
The RBCT trial, widely regarded as the most comprehensive and evidence-based evaluation of the effectiveness of culling badgers to reduce bovine TB in cattle herds, was conducted with meticulous attention to detail and thoroughness. This approach instills trust and reliability in its findings, ensuring the audience can rely on its conclusions.
While the RBCT has been fully published and undergone peer review, it’s important to acknowledge that some doubts about its validity have been raised. These concerns stem from the operations being suspended for a year during the Foot and Mouth Disease outbreak. This suspension could have potentially affected the trial’s results, and it’s a factor that should be considered in our discussion about the RBCT’s findings and implications.
So, how did the field trials work?
The RBCT was set up similarly to a medical trial today. Thirty areas were grouped into ten sets of three, each called a triplet.
In July 1998, the government’s Randomised Badger Culling Trial commenced. Thirty areas were grouped into ten sets of three, each called a ‘triplet’. Each set comprised three large sites known as ‘sub-populations’, which were further divided into smaller sample areas called ‘setts’ – many of these are located on private farmland.
The first triplet uses Proactive Culling.
This means the badgers were culled on a single occasion locally, on and near farmland where recent outbreaks of bovine tuberculosis (TB) had occurred in cattle. It is difficult to calculate how many badgers lived throughout this part of rural England before the start of the RBCT. Still, estimates suggest several hundred may have lived within its boundaries at study commencement.
The second triplet used reactive culling. In these areas, the badgers were culled on a repeated (approximately annual) basis across all accessible land with the Farmer’s consent.
The third triplet area was Control (no cull)
The Zones: When looking at maps of England, you will see that it is divided into numbered zones for postal deliveries, weather forecasting, etc. These 30 districts are also used in scientific research on specific locations within England.
For researchers to establish whether or not culling badgers had an effect on bovine TB incidence in cattle, they were required to group adjacent samples and ensure they had 20%, 40%, 60% or 80% culling within each subpopulation by randomly selecting suitable land holding ownerships from landowners who elected to participate (“Farmer-led sampling”).
The scientist’s plan was to cull the badger population across ten areas of 100 km2 each.
In Proactive culling areas, the Badgers would be hunted down and killed over the entire area of these ten spots.
In reactive culling areas, badgers were only culled on farms where infected cattle herds had been discovered—the operation aimed to remove every badger family that could have accessed the breakdown farm.
In the Control zones, surveys were conducted for badgers without culling during the trial period.
The British government was forced to put a hold on reactive culling when it was determined that TB in cattle had become more severe than in the comparison sites.
Analysis of proactive culling revealed both positive and negative consequences. Farms situated in the centre of the culled area saw a relative drop of 25% concerning TB incidents, whilst farms on the outskirts saw an increase of 25% compared to control areas. Something was not working.
The scientists believed that the harmful effects caused by both reactive and proactive culling were due to disruption in the badger population, which led to the increased spread of TB. They described this phenomenon as a perturbation, a consequence of culling badgers that were not previously known but discovered by the RBCT trials.
The Perturbation effect
In the context of badgers, “perturbation” refers to any changes in their behaviour that result from their population being culled.
Most of the evidence for perturbation in badgers comes from the Randomised Badger Culling Trial (RBCT).
The experiment was set up to check if culling badgers could decrease bovine TB cases in cattle.
The RBCT found that while instances of TB in cattle declined inside proactive badger cull areas, they increased in neighbouring 2-kilometre zones. This ‘perturbation effect’ is thought to be because fewer badgers are left behind in the area, causing them to roam over wider grounds and potentially increase contact with cows, hence increasing chances of transmitting the disease, though this has yet to be proven.
So, perturbation of badgers is believed to lead to increased TB outbreaks among cattle surrounding culled locations.
The Conclusion of the RBCT Trials
Taking account of the cost of culling, as well as the compelling results of the trial, the ISG concluded After considering the high cost of culling and evaluating the trial results, the Independent Scientific Group (ISG) concluded that badger culling is not an effective way to control bovine TB in Britain.
Instead, they recommended improving cattle detection and removal to reduce transmission between both animals. Additionally, improvements to farm biosecurity measures can also reduce risk while continuing to research vaccine development for both species.
Despite acknowledging a decrease in adverse edge effects and continuing positive effects after halting proactive culling trials, the ISG maintain their recommendation against culling.
Before the 2010 General Election, David Cameron’s Conservative Party made manifesto pledges designed to appeal to large landowners and farmers. These included a return for Foxhunting and a licenced cull of Badgers to stop bovine TB in cattle.
Following the 2010 General Election, David Cameron’s Conservatives formed a coalition government and began to implement their manifesto pledges.
Still, the Lib Dem coalition leader Nick Clegg was vehemently opposed to making fox hunting legal again, so with one of their pledges forced onto the backburner, they ‘had to make good’ on the other. They announced the culling of badgers would begin in two pilot areas of Gloucestershire and Somerset in 2012.
The badger culls, instituted by DEFRA in 2013, have been highly suspect since their inception.
Dismissing scientific evidence provided by the RBCT, DEFRA cherry-picked which methods they would utilise, disregarding those that didn’t suit the government’s agenda.
The 2013 pilot culls showed a jarring contrast between the RBCT’s two-week intensive culls and DEFRA’s 6-week mandate. Consequently, the pilot cull areas were much smaller than those studied by the RBCT and yielded incomparable results.
Now, after ten years of culling, and despite the government’s stated aim of ending the badger culls in 2025, I am deeply concerned that should the licence be issued in 2025, those cull zones would be subjected to a further nine years of intense killing—four years of concentrated eliminations followed by five years of supplementary culling. The badger culls could extend another decade.
After ten years of badger culling, the badger population has been reduced by 200,000 individuals—or around 50% of the badger population nationally. Remember that the licensed cull zones do not cover the whole of England and Wales, so clearly, badger populations in the South West must be at extreme risk of local extinction.
My frustration grows with each passing day as I observe DEFRA and Natural England withhold critical data from the public, leaving us to wonder if the culls are making a difference at all. The 20-month reporting delay is completely unacceptable and it’s time that we demand transparency; there must be a 12-month maximum to make all data available to the public.
My frustration grows with each passing day as I observe DEFRA and Natural England withhold critical data from the public, leaving us to wonder if the culls are making a difference. The 20-month reporting delay is wholly unacceptable, and it’s time for us to demand transparency; there must be a 12-month maximum to make all data available to the public.
The RBCT was the first scientific trial paper I ever read. It provided me with clear and comprehensive insights into the field trial methods used.
It soon became clear to me that this is an exceptionally robust and logical model for any scientific study, so much so that after many years of reading scientific papers, I am still looking for one that matches its clarity and conciseness.
It is disconcerting to think the Cameron government could be so quick to ignore the findings of such a widely respected study—a study paid for by UK taxpayers at a hefty £50 million.
Tragically, that is precisely what they did. Worse, successive Conservative governments have continued the flawed policy to the detriment of badgers, but also to cattle and farmers – all of whom have suffered from the fatally flawed policy, when it is clear that the disease, BovineTB lies within cattle herds, more specifically, intensively farmed dairy herds.
In recent years, we have seen scientists’ incredible ability to produce vaccines in record time. Yet, the British government has taken over a decade to develop a cattle vaccine—even though one already exists—the BCG that many people had at school until recent years—and still claims that the development of a cattle vaccine is several years away.
As we prepare to explore the multifaceted issue of bovine tuberculosis in future podcasts, we must consider the problem of cattle, badgers, and their related diseases.
The Independent Scientific Group (ISG) has never wavered from its stance that culling is not the answer. In addition, Lord Krebs, who created the Randomised Badger Culling Trial (RBCT), has stated in the House of Lords on many occasions that the government estimates suggesting a 16% decrease in herd breakdowns over just nine years were “insufficiently effective ways of controlling disease.”
10 years later, Lord Krebs was right — yet the British government still refused to acknowledge the science and continued killing off badgers across England.
You have to ask yourself why our government is so determined to continue, despite the science, the poor performance and outcomes of the culls, and the huge amount of opposition from the public—why are they protecting an industry that is in terminal decline, whose products are the food of another animal’s babies, and whose products are a known health risk to us, worth protecting?
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Further Reading
Badger Culling – RBCT and Policy -UK Government
Assessing the Effects of Badger Culling Science Reports – Nature.com