What Do Britain, Badgers, and Bullwinkle Share? | @GrrlScientist

The UK cattle industry‘s outbreak of bovine tuberculosis causes the deaths of more than just cattle: it also has triggered an all-out war on wild badgers. Why?

by GrrlScientist for Forbes | @GrrlScientist

European badger (Meles meles). (Credit: kallerna/CC BY SA 3.0).

The UK has been struggling with tuberculosis in cattle for the past couple decades. This is not good for the cows, and the farmers aren’t too pleased, either. So of course, there is a big effort underway to control the disease: cattle are tested for bovine tuberculosis (bTB) antibodies, and if even one has bTB antibodies, all cattle in the herd that directly contacted the “reactive” individual are culled, and restrictions are placed on the movement of nearby cattle to prevent the disease from spreading.

There is a vaccine for bTB, but this works by stimulating antibody production, so vaccinated cattle test positive for bTB antibodies. Although effective, the vaccine is useless in practice: if you are a farmer and one of your cows tests positive for bTB, you can just claim it’s been vaccinated. (Very naughty, but also very understandable when the alternative is to kill off part of your livelihood.) Clearly, other methods of controlling bTB are needed.

This is where badgers enter the picture. It has been known for a long time that bTB is also carried by other animals, and by wildlife. So it is reasonable to assume that wildlife could be partially responsible for transmitting bTB to cattle. For years, UK farmers specifically pointed at the European badger, Meles meles, as being the main vector spreading bTB. After much shouting, the UK government ran a big experiment from 1998 until 2006 known as the Randomised Badger Culling Trials. These trials were designed to see if mass killing badgers would reduce bTB in cattle.

The findings were straightforward: although culling might result in a small reduction in bTB in the area where the mass badger killings took place, this action also caused a larger increase in bTB incidence in adjacent areas. This was known as the “perturbation effect”. Basically, mass killing freaked out the badgers, and they responded by running away — as would we all. A small number of the runaway badgers were infected with bTB, so of course, they took their bTB with them and infected other badgers along the way as well as cattle in the surrounding areas.

Based upon these trials, the government concluded that culling badgers was A Bad Idea.

But in the next general election, the government changed. Incoming government officials had a different attitude towards the previous administration’s bTB scientific evidence: they hated it. So they started a new badger killing trial of their very own and, as an added bonus (to make a repeat trial more palatable to the taxpayers), it was designed to be cheaper than the original trial.

To ensure that everything was proper, the government appointed a panel of independent scientists to examine the results of this new trial to determine their validity. This expert panel concluded that the badger mass killings were ineffective because (a) they didn’t kill enough badgers in the trial area to reduce bTB, (b) the mass killings caused even bigger perturbations than did the original trial, and (c) the badgers that had been shot took an inconveniently long time to die.

Unfortunately, the government — especially the environment secretary, Owen Patterson— didn’t like these findings, either. So they fired their own panel of experts.

This is where our hero, ecologist Rosie Woodroffe, comes in. Instead of explaining her badgers-and-bTB research to her somewhat befuddled captive audience in the pub, instead of ranting about how the current government was doing the exact opposite of what her research suggested, she instead explained how scientists make sure their research results are meaningful instead of fanciful. Basically, how can we know that mass killing badgers leads to a perturbation effect when such effects might happen anyway? Rather than using badgers to explain how scientists ensure that their research findings are valid, she described another experiment — a peculiar experiment — that took place in the United States, where a scientist ended up throwing snowballs covered with his own urine at wildlife whilst dressed as a moose.

Cited (in the video):

Joel Berger, Jon E. Swenson, Inga-Lill Persson (2001). Recolonizing Carnivores and Naïve Prey: Conservation Lessons from Pleistocene Extinctions, Science 291:1036–1039 | doi:10.1126/science.1056466


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Originally published at Forbes on 29 January 2016.