Bovine TB

Thankfully, Bovine TB is not an issue for the North East of England, however, DCBG continues to support the campaign against culling badgers in England and Wales. Please lobby the govenment to keep up the pressure, especially in the light of recent announcements by the Welsh Assembly.

Below is an article written for us by Dr Richard Yarnell (former Chief Executive of the Badger Trust) last year, published by Durham Wildlife Trust in their Magazine Winter 2007.

Where now in the fight to save the badger?

By Dr Richard Yarnell, Chief Executive, Badger Trust

In June, the Independent Scientific Group (ISG) published its report on the Randomised Badger Culling Trial (RBCT) to determine whether or not culling badgers prevents the spread of bovine TB to cattle. It concluded that "badger culling can make no meaningful contribution to cattle bTB control in Britain".

When a dead badger was first found with bTB in the early 1970s it was clear that badgers could get bTB from cattle, and that those badgers could potentially re-infect livestock. The standard way of mitigating against re-infection was to remove the badger. Vets and farmers thought that if you had fewer badgers, you'd have less disease. But after 20 years of gassing and trapping badgers, bTB was still increasing in cattle. The strategy was not working. It was hoped that the RBCT would shed light on the problem.

Three treatments were included, each consisting of ten 100km2 areas in the Southwest of England. They were:

  • Proactive culling to remove as many badgers in each area as possible;
  • Reactive culling, which would kill all badgers on any farm that had a bTB breakdown in cattle and;
  • a survey area where no culling would take place but bTB levels in cattle would be monitored.

The reactive culling trial areas showed a 27 per cent increase of bTB in cattle when compared with survey-only areas, and badger culling was suspended. By contrast, the proactive killing areas yielded a 25 per cent decrease in bTB in cattle offset by a 26 per cent increase in the surrounding areas. Therefore, smallscale culling increased bTB, and although largescale culling did show a positive effect this was counteracted by the increases bordering the area.

The cause of these somewhat counter-intuitive results can be explained by badger behaviour when the population becomes disturbed via culling, what the ecologists have called the 'perturbation effect'. With fewer badgers, territorial boundaries break down and individuals begin ranging further. It is this expansion of ranges that are responsible for the increase in bTB. More movement results in a greater chance of disease transmission.

The only way to combat the effect is culling over a large enough area, so that the positive effects of widescale culling outweigh the negative impacts, or by culling within areas that have boundaries impermeable to badgers. However, very few barriers exist as badgers can swim rivers, cross roads, and climb over or dig under fences.

The ISG estimated that for culling to be beneficial, areas greater than 300km2 would have to be culled. In addition, all badgers would have to be removed in simultaneous culling operations throughout the entire area and repeated for at least five years. This would be a huge logistical problem and one that the ISG believe to be impractical. Even then, areas surrounding the cull area would still be susceptible to elevated levels of bTB due to perturbation.

And where would the culling end, because as soon as culling stops badgers would start to migrate into the culling zone spreading the disease once more? The only end point is to keep culling until a badger vaccine can be developed which is still likely to be a decade away. The ISG concluded that badger culling could not contribute to the meaningful control of bTB in cattle in the UK. Instead they suggested improved cattle testing regimes.

In the long-term, a badger vaccine is the best solution. But in the short term, keeping badgers out of farm buildings could have a dramatic effect on reducing the risk of transmission.

The RBCT has shown that badger culling is expensive, logistically-challenging and because of the perturbation effect unlikely to help control the disease. The Government now has the sound science. What remains to be seen is whether they will turn their backs on the bulk of scientific evidence and sanction a cull to appease the farmers and vets who simply do not want to take responsibility for the disease.