Uncontrolled and illegal disturbance of badgers has “contributed significantly” to new bovine tuberculosis (TB) outbreaks in nearby cattle herds, according to a Queen’s University study.
Researchers concluded that “illegal persecution of badgers does not reduce infection risk of bovine TB in cattle and may play a role in maintaining epidemic hotspots”.
Farm-level risk factors including the number of cattle movements, how often new cattle were imported, previous bovine TB history and the proximity of neighbouring farms with a bovine TB history, “were far more strongly associated with new cattle herd breakdowns than measures of the badger population or badger persecution”.
The study, which appeared in the journal Natural Scientific Reports, found that some 5 per cent of badger setts in Northern Ireland had signs of “illegal interference or persecution”.
Researchers found sett entrances being blocked with soil, boulders and branches. Some were pumped with slurry, were ploughed over or farm debris was dumped on top of the sett. In other cases they were damaged by livestock trampling or through the construction of roads or houses.
The study was funded by the Wellcome Trust and conducted by the Institute for Global Food Security at Queen's University, in conjunction with the University of Glasgow and the Agri-Food and Biosciences Institute.
Study leader Dr David Wright said that while interference with badger setts was relatively rare it was "clustered in known bovine TB hotspots in cattle", and the research hypothesis was that those taking action against badgers might actually contribute to maintaining the disease.
According to the researchers, the stronger link between farm-level risk factors and the incidence of bovine TB suggested that disease control could be improved by “increased frequency and accuracy of cattle testing, development of more sensitive tests and improved farm biosecurity”.
Annual testing
Queen's university lecturer in conservation biology Dr Neil Reid said the link between badger persecution and bovine TB in cattle could be because persecuting badgers perturbed the population stimulating spread of the disease.
Alternatively it could be because farmers were more likely to persecute badgers if their livestock had previously had a TB breakdown, Dr Reid said.
The researchers pointed to the £100 million spent by Britain in annual testing, slaughter and compensation. They said badger culling showed decreased prevalence of TB in cattle in cull areas but an increase in neighbouring herds so that the total impact has been judged negligible.
Minister for Agriculture Simon Coveney said recently that TB rates had fallen by almost 40 per cent since 2008 through the Department of Agriculture's eradication programme.
He added that in Northern Ireland badger removal was “not prioritised” and the TB rate was twice as high as in the south.
An ongoing study by Trinity College Dublin zoologists, the Department of Agriculture and the National Parks & Wildlife Service found that badgers travel long distances to avoid cattle.
