Pete E said:
Heres some solid scientific evidence then, although it might not lead to the conclusions you expect.
From New Scientist...
SEVEN years ago, the UK government set out to answer a seemingly simple question: does culling wild badgers, a protected species thought to be responsible for spreading tuberculosis, prevent the disease spreading to cattle? This week the answer finally arrived. But it was not the simple yes or no answer that most people had hoped for.
In the worst affected regions of the UK, in the south-west of England, bovine TB infects about 10 per cent of the cattle population. Farmers have long blamed badgers for spreading the disease, and a trial was launched in 1998 to find out whether culling could quash it. Since then 11,000 badgers have been killed in 30 trial areas of about 100 square kilometres each.
Christl Donnelly of Imperial College London and her team analysed rates of TB in cattle both inside and beyond the culling zone boundaries. They found that intense "proactive" culling within the zone reduced TB incidence by 19 per cent, but that rates increased by 29 per cent in a 2-kilometre-wide ring around the zone. So reducing TB within the culled zones happens at the expense of previously disease-free farms just outside (Nature, DOI: 10.1038/nature04454).
A second study, led by Rosie Woodroffe of the University of California, Davis, suggests that this may be because the culling pushed badgers outside their usual territories. The team tracked the badgers by placing indigestible colour-coded beads in bait, which allowed them to identify which set a badger was from by examining its faeces.
Woodroffe and her colleagues report online in the Journal of Applied Ecology (DOI: 10.1111/j.1365-2664.2005.01144.x) that the culling disrupted badger territories, making survivors roam much wider than usual and reach farms beyond their usual range.
Taken together, the studies confirm that proactive culling prompts roaming badgers to spread TB beyond the culling zone. "Even with widespread culling, you help some farmers but make things worse for others," says Donnelly. Culling will only work if the culling zones are vastly extended and badgers are prevented from roaming outside them, or if culling takes place right up to a natural border.
The results leave the government with a dilemma. "If they ban culling, they could end up with a serious problem of patchy illegal culling, which would probably make matters worse for local cattle," says Donnelly. "But if they go ahead with culling, some farmers will be unhappy because they're on the periphery."
The Badger Trust conservation group wants the government to shift the focus towards preventing the spread of TB among cattle by improving diagnosis and testing. Its spokesman Trevor Lawson says that since Northern Ireland introduced such measures in November 2004, rates of TB there have fallen by 40 per cent.
