YNET

The decline of the hedgehog is mainly caused by the huge recent expansion of the badger population. In both time and place there is a strong negative correlation between badger numbers and hedgehog numbers. The scientific evidence that an increase in Mr Brock may well be the chief cause of Mrs Tiggywinkle’s demise is overwhelming. There’s the direct evidence – the hollowed-out prickle-bearing skins left behind after a badger eats a hedgehog. Only badgers can open a hedgehog after it rolls up in defence with prickles on the outside. Foxes and dogs cannot. Badger predation is often found to be the main cause of hedgehog death in studies in this country. There’s the timing evidence. The decline in hedgehogs coincided with the rise in badgers since the latter’s protection began in the 1970s and was strengthened in the 1990s. Anecdotally, there are clear-cut cases to show this is likely to be cause and effect, not coincidence. Kew Gardens had a thriving hedgehog population until the mid 1980s when badgers first arrived there. Today, says the Royal Botanic Gardens’ website, “Kew is teeming with badgers”. There are now more than 20 badger setts and hedgehogs are hardly ever seen, and if they are don’t last long. Habitat change and development cannot be the cause in Kew, because there has not been any. There’s the spatial evidence. Throughout England hedgehogs (great worm eaters) have vanished from worm-rich pastureland, where badgers thrive, and cling on only in suburban gardens and amenity grassland, where badgers so far have not penetrated much. Even here, as one study put it: “the probability of hedgehog occurrence in suburban habitats declined towards zero in areas of high badger density.” As a general rule, wherever badgers are present at a density higher than about one main sett every four square kilometres, hedgehogs are absent. In most of rural England, sett density is two or three times higher. There’s the behavioural evidence. Back in the 1990s, ecologists discovered that the smell of badgers alone is enough to deter hedgehogs from entering an area. And hedgehogs released into areas of excellent habitat high-tailed it out of there if they smelt badger. They do not wait to be eaten. There’s the international evidence. Sweden has also blamed its decline in hedgehogs on rising badger numbers. In the Netherlands, scientists reported this yearthat hedgehogs are now confined mostly to urban areas, despite roads and development, because of the spread of badgers in rural areas. There’s the experimental evidence, which is the clincher. The randomized badger control trials, carried out between 1998 and 2006 in 30 different parts of the country, provided an opportunity to see what happened to hedgehog numbers if badger numbers were reduced. In pasture land, where hedgehogs are mostly extinct, there was of course little effect. But in “amenity grassland” – parks, lawns, gardens, playing fields etc – there was a dramatic explosion in hedgehog numbers in those areas where badgers were culled: hedgehog density almost trebledfrom an average of 0.9 per hectare to 2.4 per hectare in just five years. By contrast in the control areas where no badgers were culled, the hedgehog density remained unchanged at 0.3 per hectare over the same period.  So we know one way to increase hedgehog numbers: reduce badger numbers. No other approach has been demonstrated to have such an effect. Given that badgers are highly effective predators of bumble bees (those who try to study bumble bees complain that most of the nests they find get dug out and eaten by badgers) as well as of ground nesting birds, and that they carry bovine tuberculosis, there is little doubt that lower badger densities would be good for the ecology of the British countryside as well as for farming. There is nothing natural about the density at which badgers and foxes live in Britain today.