Out of the woods?
The latest developments surrounding the badger cull debate
After years of controversy, the government has announced it will phase out badger culling, but there’s no guarantee that it, or the debates surrounding it, will end anytime soon.
IIt’s a warm and wet Friday evening at the end of January 2020, and a good 150 people have gathered in Merton College’s TS Eliot Theatre in Oxford, to listen to professor Christl Donnelly – a statistical epidemiologist with an expertise in modelling how diseases spread – deliver a lecture entitled ‘Badgers and Bovine TB: Is it all black and white?’
Among the audience are professor David MacDonald, one of the country’s leading zoologists, and the chief executive of the Badger Trust, Dominic Dyer.
Donnelly is an éminence grise of the science on badgers and bovine TB (bTB), having done the number-crunching for most of the key papers that have helped dictate policy on the issue for more than two decades. In this context, the title of her lecture is odd – government ministers, at least since 2010, have seen her conclusions as entirely black and white. Her science has shown that badger culling works, and the government has enthusiastically adopted it as a central plank of efforts to tackle bTB.
Spreading far and wide
Badger culling in England is now permitted across more than 40 areas of the country and in more than half of the area of the counties of Devon, Dorset and Cornwall. Some 30,000–40,000 badgers are shot on an annual basis, with the total figure since 2013 estimated to be more than 100,000. But then, TB is a serious problem: on average, more than 30,000 cows are slaughtered every year after becoming infected with the disease and costs to the taxpayer top £100m.
“The badger is an iconic, protected species and no one wants to be culling them forever.”
Then, in early March this year, many media outlets report a screeching government u-turn. “Badger cull to be replaced by vaccines in bovine TB fight,” says BBC online. Wildlife groups are equally enthusiastic about the new policy. “For the first time, the government has put forward a credible exit strategy from widespread indiscriminate cruel badger culling,” tweets the Badger Trust’s Dominic Dyer. “The badger is an iconic, protected species and no one wants to be culling them forever,” says the Department of Environment, Food & Rural Affairs (Defra) in its ‘Next steps’ strategy document.
There’s only one problem with this eruption of good news, says conservation ecologist Tom Langton – it’s entirely fictitious. Promises to end culling are hollow and there’s little money to support an increase in badger vaccination, he warns. Plans to develop a vaccine for cattle in five years’ time are riddled with complications and have been heard before and never materialised.
Langton may have a point. An email to BBC Wildlife from the Defra press office concedes that culling will continue for some time. “Natural England issues intensive cull licences for a minimum of four years,” Defra explains, “so we would expect any existing licences to run their course for these to be considered effective.” Initiating new culls will
“remain an option where epidemiological assessment indicates that it is needed,” the strategy document says. Defra, in other words, reserves the right to carry on killing badgers for as long as it deems it necessary.
Langton has calculated that a further 200,000 badgers will be killed between now and 2030. “I see nothing positive in this,” he says. “It’s a spectacular can-kicking exercise.”
It’s worth noting that the NFU, which has consistently advocated badger culling as a way of tackling the disease in cattle, welcomes the retention of intensive culling where required. “Any move away from an intensive culling policy – whether that’s in 5 years, 10 years or longer – should not be rushed, and sufficient science and evidence must support any such move,” says deputy president Stuart Roberts in a statement.
A long history
Whatever the truth, it’s important to remember that this is just the latest in a very, very long line of plans, strategies and responses, as the government tries to stem the rising tide of TB in cattle. Indeed, you have to go all the way back to 1971, when the UK hadn’t yet joined the EEC, let alone left the EU, to the discovery of a single dead badger riddled with TB to understand why we still cull badgers today. In nearly half a century, there have been only 10 years when badgers have not been killed somewhere, because, it’s believed, they give TB to cattle.
The ecologist (Lord) John Krebs noted in his report of 1997 that the old Ministry of Agriculture, Fisheries and Food (MAFF) had begun to suspect badgers were “a potential reservoir of Mycobacterium bovis infection for cattle” in the 1960s, as efforts to eradicate the disease – which affected 40 per cent of cows in the 1930s – stalled.
It wasn’t until 2013 that someone – Donnelly, in fact – came up with a figure. She calculated that 5.7 per cent of TB breakdowns were attributable to badgers (with a range of anywhere from 1–25 per cent), though she also said that this rose to 50 per cent as a result of those cattle infected by badgers passing it onto other herds.
But Langton, who has spent a large part of the past seven years studying badger culling science, says no one has even shown how badger-to-cattle transmission occurs. Talking to scientists, he says he’s heard theories of cows eating infected badger dung and inhaling their breath. He scoffs at both notions as regular events.
The critical point is this: many people believe that identifying badgers as a “reservoir” for bTB infection all those years ago has led to the government and scientists focusing disproportionately on them rather than the far more significant source: the cattle themselves – at least 94 per cent of new cases, if Donnelly is right.
But if 6 per cent of cattle herds do become newly infected with TB as a result of contact with badgers, what does the science say about the impact of culling them?
Results from the Randomised Badger Culling Trial, which ran from 1998 until 2004, is the best data we have for this. Using complex modelling, it found that culling badgers over four years resulted in declines of bTB of 20–35 per cent within the cull zones, but that levels of the disease rose in a narrow strip surrounding the area.
This may be because of the so-called perturbation effect. Professor Rosie
Woodroffe, a behavioural ecologist at ZSL, was one of the scientists who discovered it while investigating the data from the RBCT data. “When you cull badgers, you lower their density and destroy their territorial behaviour,” Woodroffe says. “Suddenly those badgers are ranging more widely and there’s more opportunity for interaction, so the disease can move more widely, too.”
As a result, the theory goes, any decrease in bTB rates is offset by increases on the edge of the cull zone by nearly 30 per cent. From these figures, it was estimated that should you cull over 150km² for four years, then the overall benefit over nine years would be a reduction in bTB in cattle of 12–16 per cent.
Crunching the numbers
More recently, some data from the culls that started in 2013 has emerged. Last year, a peer-reviewed paper (a study that has been read and approved by other scientists) looking at data from the first two culling zones found that levels of bTB in cattle had decreased by 66 per cent in Gloucestershire and 37 per cent in Somerset during the first four years. Which sounds promising, until you realise there are several caveats.
First of all, the modelled decreases observed were greater than those for the RBCT, suggesting, the authors say, “there are other mechanisms at play that amplify effects associated with badger controls. Implementing culling may lead to greater focus on cattle controls, TB testing quality and implementation of biosecurity.” And then there’s what happened in 2018 – bTB levels rose again in Gloucestershire, with measured TBbreakdowns standing at 23, just one below the level they were at in 2012, the year before the badger culls started.
Some people argue that there is a much better alternative to culling. They agree that badgers transmit bTB to cows and that we need to tackle it through vaccination if we are ever to eradicate it from our cattle herds. Chief among these people is Rosie Woodroffe.
We know that if you vaccinate a healthy wild badger it protects that individual from succumbing to the disease, but not whether it will reduce the prevalence of bTB in badger populations as a whole, or whether that translates into reduced levels of bTB in cattle.
Woodroffe is currently exploring the first of these unknowns in her Cornwall-based project, but she suggests that vaccination offers significant advantages over culling in a number of respects. Even if you accept that culling reduces levels of bTB in cattle (which she does), it definitely does the opposite in badgers. “Culling increases the prevalence of the disease in badgers,” she says. “It’s the opposite of what an eradication programme should do. In that context, vaccination is so much more promising.”
Woodroffe adds that even if most transmission is cattle-to-cattle, it’s still important to tackle the disease in wildlife. “It’s hard to say to farmers, ‘We know that badgers can give TB to cattle, but we’re not going to do anything about it.’” And she points out that vaccination can cost about one quarter of the price of culling – roughly £600 per km² per year compared with £2,250 per km² per year. One of the reasons for this, says Woodroffe, is the high levels of policing needed where culls take place.
But for people who say it is unclear whether badgers give TB to cattle, vaccination is a waste of time. And they think they have some real, practical evidence for this in the shape of Gatcombe Farm, near Seaton in Devon.
“Culling increases the prevalence of the disease in badgers – it’s the opposite of what an eradication programme should do.”