Gareth Enticott argues that precise assessment of the effect of badger perturbation to bTB incidence can only be made by analysing farmer behaviour and its effects in badger culling zones.
Statistics from Altmetric.com
Gareth Enticott is a reader in human geography at Cardiff University
Badger culling to reduce bovine TB (bTB) in cattle represents the kind of ecosystem disturbance that could result in perturbation effects.
Badger perturbation has been recognised as a challenge to badger culling policies since the Independent Scientific Group’s (ISG) randomised badger culling trial (RBCT).1 Its results concluded that culling had disrupted the territorial systems of badgers, resulting in them ranging wider and immigrating into non-culled areas. This perturbation effect was associated with an increase in Mycobacterium bovis transmission, undermining any beneficial effects of badger culling on the incidence of cattle herd breakdowns.
However, the ISG’s work also highlighted how farmer behaviour can play a role in the epidemiology of bTB. Research revealed the contribution that cattle purchasing and cattle movements make in translocating disease. But, these analyses did not extend to considering how changes to farmer behaviour in badger culling zones can mediate the effects of badger perturbation arising from badger culling. Given the importance of the perturbation effect in government policies, and of badger culling as a solution to bTB, this is an important omission.
Behavioural responses of farmers to badger culling may act as a significant confounder to the perturbation effect and, indeed, the contribution badger culling makes to bTB incidence. These behavioural effects have been widely researched in other studies and show how the public response to policy interventions may actually have unexpected behavioural consequences. Two related perspectives help explain these behavioural effects.
First, risk compensation theory suggests that policy interventions that reduce risk are counterbalanced by greater risk taking. Adams2 suggests that everyone possesses a ‘risk thermostat’ (ie, the propensity of risk that one will take). The propensity of risk-taking varies between individuals, and is influenced by the potential rewards of risk-taking and the experience of losses. Importantly, Adams suggests that risk-taking decisions represent a balancing act of potential rewards and losses but that, overall, people seek to maintain a constant level of risk-taking. Attempts to modify risks through risk reduction regulations or interventions may have limited impact because a person will adjust their behaviour in relation to these changes. For example, the wearing of seat belts and therefore increased sense of safety may just encourage faster driving.
Secondly, the ‘spillover effect’3 refers to positive behavioural adaptations arising from the promotion of simple and easy-to-adopt behaviours, which act as a ‘wedge’ to drive further behavioural adaptations. For example, studies have found a range of connections between different environmental practices, such as purchasing organic food, recycling, minimising waste, and making better transport choices.
In response to a badger cull, farmers may buy cattle more frequently and/or from high-risk areas
It is plausible to expect behavioural adaptations among farmers in response to badger culling policies. Risk compensation behaviour is likely because badger culling meets the prerequisites for risk compensation theory 4: badger culling is highly visible; it affects risk perception; farmers may benefit financially from taking risks; and farmers are largely free to take risks. For example, in response to a badger cull, farmers may buy cattle more frequently and/or from high-risk areas if they believe that the main cause of bTB is badgers. These motivations may be enhanced where farmers feel they lack ‘procedural justice’ – where they do not trust the government or experts to resolve the problem of bTB . For the RBCT, it is plausible that badger culling may have resulted in greater risk taking by farmers in the culling compared with control zones. Changes in bTB incidence in these zones may be a result of these behaviours, or at the very least the behaviours might offset some of the transmission ascribed to the perturbation effect.
Spillover behaviours may be encouraged by the controversy around badger culling – farmers may want to be seen to be ‘doing the right thing’ and may purchase replacement stock from low-risk areas and put pressure on others not to purchase cattle at risk of spreading bTB. Where farmers feel part of the solution to bTB or feel they are treated fairly by the government, this may lead to other positive spillover effects, such as implementing on-farm biosecurity measures.
Perturbation theory has had a significant effect on the design and implementation of badger culling policies. However, the extent to which badger perturbation contributes to bTB transmission should be questioned when there are plausible behavioural factors that may have a role. Having a better understanding of why farmers react to badger culling in different ways would be helpful for the management of bTB. We need to assess their risk compensation and spillover behaviours, and monitor practices such as on-farm biosecurity or herd management.
Given that the bTB has been described as a complex challenge requiring interdisciplinary insights, we should include experts in social and behavioural sciences to undertake this work. Until this behavioural analysis has been done, caution should be applied to the significance of the badger perturbation effect in managing bTB.●
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.