Badger culling could actually be making the problem of tuberculosis in cattle worse, new research suggests.
The study indicates the practice drives the surviving creatures to cover 61% more land each month than before the cull began.
Researchers from the Zoological Society of London (ZSL) and Imperial College London say this means badgers explore new areas as individuals are removed from neighbouring groups and territories open up.
Published in the Journal of Applied Ecology, the research found that badgers also visited 45% more fields each month.
The odds of a badger visiting a neighbouring territory after a cull increased 20-fold, potentially increasing the risk of TB transmission to both cattle and other badgers, according to the scientists.
They say the changes were witnessed as soon as culling began, meaning even badgers that were killed may have first spread the infection over wider areas while management was being implemented.
However, the animals spent less time outside of their setts in culled areas – spending on average 91 minutes less per night out and about.
Researchers believe this could be linked to reduced competition and increased food availability as badgers are removed from the population.
Lead author and ZSL-Imperial PhD researcher Cally Ham explained: “Badgers spend a large proportion of the night foraging for food above ground, and as culling reduces the size of the population, competition for food will also be reduced.
“We believe this accounts for the reduced activity levels, as well as bold individuals becoming obvious targets for culling and being quickly removed from the population.
“Because culling partly relies on shooting badgers moving around at night, the fact that badgers were active for fewer hours per night could actually be undermining culling efforts to further control badger numbers.”
Professor Rosie Woodroffe, at ZSL’s Institute of Zoology, said: “As badger-to-cattle transmission is likely to occur through contamination of their shared environment, and TB bacteria can remain viable for long periods of time in the environment, the effects of increases in ranging behaviour could create a source of infection for several months – long after the individual badger has been culled.
“In contrast, studies have shown that vaccination prompts no changes in badgers’ ranging behaviour.”
The research group from ZSL’s Institute of Zoology and Imperial’s MRC Centre for Global Infectious Disease Analysis studied 67 badgers across 20 cattle farms in areas with and without farmer-led culling in Cornwall, collecting GPS-collar data between 2013 and 2017.
Last year the Government commissioned a review of its strategy for tackling bovine tuberculosis (bTB) in livestock amid ongoing controversy about badger culling to control the disease.
Measures to tackle the disease include cattle testing and movement controls, improving “biosecurity” or protective measures to prevent disease spread on farms, developing vaccines for cattle and badgers and culling badgers – which can spread TB to cattle – in 32 areas of England.
The independent review found farmers must do more to tackle the spread of tuberculosis between cattle, which is a bigger part of the problem than badgers.
While it said that culling showed a “real but modest effect” and was a judgment call for ministers, the review led by Sir Charles Godfray said poor take up of biosecurity measures and trading in high-risk livestock was hampering disease control.
Since the UK Government implemented the culling policy in 2011, ZSL scientists have been working to understand whether badger vaccination could be used to reduce the infection of TB in the UK’s badger population, and so help control TB in cattle.
A spokesman for the Badger Trust said: “The latest research from ZSL shows that this mass destruction of a protected species could be resulting in perturbation, increasing the risk of TB spread in badgers and possibly cattle.”
He added: “Badger vaccination is the most cost effective and humane way of reducing TB in badgers, that do not have the disease.
“It also removes the risk of perturbation and brings farmers and wildlife protection groups together in a spirit of mutual respect, trust and confidence.
“The Government should halt the culling of badgers and move to a national badger vaccination strategy.”
A Defra spokesman said: “Bovine TB remains the greatest animal health threat to the UK, costing taxpayers over £100 million every year as well as causing devastation and distress for farmers and rural communities.
“There is no single measure that will provide an easy answer to beating the disease and we are pursuing a range of interventions to eradicate it by 2038, including tighter cattle movement controls, regular testing and vaccinations.”