Hedgehogs and Badgers

not as simple as we thought

Another update and another scientific paper to be digested before your very eyes!

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This is one of the prickliest of topics. And over the years I have been on the receiving end of grumpiness from both sides of the debate (this seems to be a common position for me - caught in the middle, offering such absurd things like nuance!)

The debate surrounds the facts that - where there are lots of badgers, there tend to be few or no hedgehogs. Where there are lots of hedgehogs there tend to be few or no badgers. Badgers can eat hedgehogs - I know this because I have actually witnessed it, while radio tracking hedgehogs in Devon (lots more about that in my book, A Prickly Affair).

The result of this is often a knee-jerk reaction. There have been articles written telling us that we should kill badgers to save hedgehogs. For example, this from Robin Page.

And when I was invited to speak to the Badger Trust AGM one year about the complex relationship, I was told, by the lovely Dominic Dyer, then the Chair of the group, that the fire exit had been left open to I could make a run for it after telling the audience that badgers do eat hedgehogs!! There was an understandable worry about anything that could demonise the already demonised badger any more!

The reality was examined by Ben Willians and published in Nature seven years ago - about the fact that the two species have what is know as an ‘Asymmetric Intra-Guild Predatory Relationship’.

Which means that while they are principally competitors for macro-invertebrates, they can, should the environment become degraded, shift that relationship to one that is predatory.

But back to the new paper - sorry for the distraction.

Katie Lee, working at Nottingham Trent University- funded by the People’s Trust for Endangered Species, has been looking at how habitat selection might be able to facilitate coexistence between the two species.

In the abstract she writes,

‘Predicting the spatial and temporal responses of species exhibiting intraguild predation (IGP) relationships is difficult due to variation in potential interactions and environmental context. Eurasian badgers (Meles meles) are intraguild predators of European hedgehogs (Erinaceus europaeus) and are implicated in their population decline via both direct predation and competition for shared food resources. Previous studies have shown spatial separation between these species and attributed this to hedgehogs experiencing a ‘landscape of fear’, but little is known about the potential role of differential habitat use. We estimated the density and occupancy of both species at 22 rural study sites in England and Wales, to explore whether food availability, habitat or the presence of badgers, explained hedgehog distributions. Hedgehog density varied significantly across major rural land uses, whereas badger density did not. Although both species coexisted at a regional (1 km2) scale, occupancy modelling showed spatial segregation at a finer (individual camera trap) scale, associated with differential habitat use. In contrast to badgers, hedgehogs were recorded near buildings, and in areas supporting lower invertebrate biomass. This is in agreement with IGP theory, whereby IG-prey may occupy suboptimal habitat to avoid predation; however, hedgehog habitat use did not vary relative to the presence of badgers. Badger and hedgehog temporal activity showed no evidence of separation. Although these findings are consistent with hedgehogs avoiding badgers via a landscape of fear, they are also indicative of differential habitat use, highlighting the need for more holistic studies considering variation in habitat selection and food availability when investigating intraguild relationships. Future studies exploring alternative hypotheses for urban habitat selection by hedgehogs are needed to better understand how possible spatial niche partitioning may support their coexistence with badgers in some areas.’

And in the discussion she concludes,

‘The results of this study demonstrate the importance of incorporating measures of both prey and habitat availability when studying population density and spatiotemporal relationships of intraguild predators and prey. Our results indicated that, at a site level, hedgehog density was significantly higher in mixed farmland than in arable landscapes that the spatial distribution of badgers and hedgehogs was associated with differences in habitat use and prey availability resulting in spatial separation, which negated the need for temporal avoidance, but that hedgehogs were absent (or below a minimum detectable density) where badger density exceeded 30.3 individuals km-2.’

It used to be thought that badger density alone was enough to mean there would be no hedgehogs, but in the paper she writes, ‘badger density threshold for coexistence may be site-specific, based on the availability of habitat, abundance of local food resources, and may depend on the scale at which coexistence is being assessed…’

The take home from this paper is, I think, that hedgehogs and badgers have the capacity to coexist as long as there is enough food and shelter. This, in turn, is also supported by the fact that hedgehogs and badgers have managed to coexist for millennia… since the retreat of the last ice sheet. What has changed is the way in which we manage the land - and the ecological deserts into which we turn farms.

If you would like to learn more about the research that the BHPS and the PTES does, please do visit their websites. And if you would like to get involved in a bit of research yourself … log onto the National Hedgehog Monitoring Programme - and join the team searching through millions of images, looking for hedgehogs!!