By Richard Young
What to do, when two of Britain’s most loved animals run up against each other?
In a study recently published in the journal PLOS One, we found that the numbers of hedgehogs living in suburban areas in rural England doubled following the reduction in badger numbers through culling. This research points to the badger, widely popular in certain quarters but of major concern in others, having a significant impact on the hedgehog, Britain’s best loved mammal.
The Defra-funded research was part of a wider project to evaluate the ecological consequences of the Randomised Badger Culling Trial (RBCT) conducted between 1998 and 2006. This long-running operation met with stiff resistance from many conservation and animal welfare groups. But it did offer an unrivalled opportunity to study the impact that an important predator has on prey and competitor species.
This type of research is particularly important as it provides information upon which to base conservation and environmental management decisions. This is particularly the case in areas that are extensively managed or affected by human activity, which leaves them missing many parts of their original food webs. For example, where large predators are missing (wolves, for example), medium-sized predators left unchallenged can have other knock-on ecological impacts.
One such predator, the badger, has long been known to prey on hedgehogs. This isn’t necessarily a cause for concern, as predator-prey relationships are natural and essential parts of functioning ecosystems. Hedgehogs and badgers have co-existed for millennia in Britain – well before the arrival of humans, and in the thousands of years since.
However studies during the 1990s showed that where badger density was high they may have a profound effect on hedgehog numbers and their ability to move around the landscape. Animal rescue and rehabilitation organisations discovered that badgers were causing high rates of mortality among hedgehogs released back into the wild in some areas.
Evidence from two citizen science surveys, run by the People’s Trust for Endangered Species over the past decade, point to a substantial national decline in hedgehog numbers. There are many suspects behind this decline – habitat loss and fragmentation as towns and villages expand, the loss of hedgerows which provide them cover and nesting sites, warmer winters and drier springs that disrupt their hibernation and invertebrate prey species, pesticides, roadkill, and a thriving badger population. But without a robust long-term national hedgehog monitoring scheme, it’s very difficult to determine the precise timing and cause.
Badgers on the up In the early-2000s, a team of us investigated patterns in hedgehog and badger populations across hundreds of square kilometres of rural southwest England and the midlands. One important finding was that hedgehogs appeared to be absent from large swathes of pastoral grasslands where they are thought to have once been commonplace. Instead we found that hedgehogs had moved almost exclusively into the villages and towns within these landscapes. It was also apparent that the likelihood of finding hedgehogs in parks and gardens declined as the density of badger setts nearby increased.
But is this correlation, or is it causation? To address this question, we surveyed hedgehogs in a number of areas which were geographically and ecologically similar, but with different levels of badger culling. Hedgehog numbers in suburban areas doubled during the five years of badger culling, and remained static in areas without culling. This demonstrated for the first time that badger predation is a strong limiting factor for hedgehog populations in these particular habitats.
But badgers and hedgehogs have always co-existed in Britain, why might there be an issue now? Until the mid to late 20th century, heavy persecution of badgers kept them at low numbers. The Badgers Act of 1973 introduced protections, enhanced by the 1992 Protection of Badgers Act. Consequently surveys published in January revealed that in the 25 years since the first survey in 1985-88, the number of badger social groups in England has doubled to around 71,600.
In pasture-dominated and mixed agricultural landscapes, and in some suburban habitats, badgers thrive with have plentiful denning opportunities and abundant food resources. The largest increases in the density of badger social groups have occurred in the landscapes that dominate southern, western and eastern England. These are also the areas where hedgehog declines are likely to be most severe.
So while there is evidence that increasing badger populations play a significant role in the hedgehog’s decline, the relative weight of the impact of badgers against the other many factors likely affecting hedgehogs is far from clear.
Badger culling won’t save hedgehogs Even with evidence of this link, it does not necessarily follow that badger culling would, or should, play any role in tackling the decline of the hedgehog. Given a multitude of ecological, social, practical, financial and legal reasons, it is impossible to see how it could ever be part of any conservation strategy.
Rather, we need to understand how to manage our countryside in a more ecologically informed and progressive manner, acknowledging that there are bound to be many trade-offs along the way. This could include creating habitats such as very large areas of woodland that could favour hedgehogs over badgers, besides offering significant environmental and social value for us.
We should also consider more radical solutions, such as restoring the ecologically important elements of our ecosystems that we are missing – such as larger predators, including brown bears and lynx – as is happening in mainland Europe. That two of Britain’s most recognisable species should appear to be pitted against each other in this way may just be what’s needed to prompt a debate on how we can encourage greater diversity, in form, content and function, in our rural landscapes for the future.