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MAMMAL CONFERENCE

THE HEDGEHOG’S PLIGHT PAT MORRIS The hedgehog is one of our most popular and easily recognised mammals, normally considered to be ‘common and widespread’. However, in recent years people have commented increasingly often that they see fewer these days or that hedgehogs no longer come to their garden. These casual observations have become so frequent as to seriously question the status of this species. Anecdotal information is insufficient to make a strong case, but there is no accurate way of estimating population size or local abundance of species like this that live at a low population density and are not amenable to large-scale trapping or direct observation in sufficient numbers to ensure statistical validity of any assessments regarding population size. Instead we have to rely upon indices of relative numbers to support suggestions that there have been changes in abundance. The most obvious index is the number of hedgehogs seen dead on our roads. In the 1990s, I began a study in which volunteers recorded the numbers seen dead on various journeys, following strict instructions that ensured everyone was making observations in the same way. Nevertheless, I was castigated for being unscientific and doing nothing more than inventing a crude method of measuring traffic density! However, there was good evidence that numbers seen dead per 100 miles driven were not related to traffic density and moreover were consistent regionally from one year to the next. More recently, my colleague Paul Bright has confirmed (with rabbits) that numbers seen dead on the road are a direct reflection of numbers alive nearby. The ‘roadkill index’ is thus a satisfactory way of indicating relative abundance from year to year and place to place. Nowadays we can harness far more observers via the internet and make comparisons with 20 years ago. It seems that hedgehog numbers have reduced by about 30% in that time and continue to decline. Moreover, data from the Game Conservancy Trust show that numbers killed by gamekeepers have halved in 50 years, and it’s not because gamekeepers are getting lazy! Surveys by both the British Trust for Ornithology and by the Peoples Trust for Endangered Species show that numbers of hedgehogs seen in gardens have declined by about 5% each year in recent times. It all points to a significant cause for concern. It is likely that many factors have brought about this decline, notably the intensification of agriculture. A century ago, when horses were abundant, their grazing created excellent feeding areas for hedgehogs who could also nest in nearby hedgerows. Changing to arable crops and removing hedges to make harvesting more efficient has left the hedgehog with poor habitat across vast swathes of our countryside. The use of pesticides to improve crop yields removes many of the beetles, worms and other creatures that the hedgehog depends upon for its nightly nourishment; deep ploughing doesn’t help either. Flail mowers thrash the grass verges of our roads, exactly where many hedgehogs will lie up during warm summer days. Garden strimmers mangle many more, not to mention the 15,000 or so that are killed annually on our roads. In urban areas, modern fencing obstructs free movement, as do the many miles of concrete barriers down the middle of our Trans. Suffolk Nat. Soc. 51 (2015)


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Suffolk Natural History, Vol. 51

motorways. Populations become fragmented into smaller units that are at increased risk of dying out. Computer modelling suggests that a minimum viable population size is around 30-40 animals, needing more than 90 hectares of good continuous habitat. Most gardens and urban parks are smaller than that and too small to support a hedgehog population indefinitely, so the animals rely on being able to access many gardens in the course of their wanderings. Impermeable fencing prevents this. Basically the hedgehog is an ancient creature that evolved long before cars, pesticides, fences and mowing machines. Modern life is ganging up on it! As if this were not danger enough, we have seen a major increase in badger numbers over the past 20-30 years, even in East Anglia where they were rare for a long time. Badgers eat hedgehogs. They are the only predators able to get past the bristling spines, using their long claws and powerful forelimbs. Perhaps more important, they also eat the same things as hedgehogs, especially worms. The same worm cannot be eaten twice. Each one eaten by a badger is one less for a hedgehog (or song thrush or anything else). Badgers are big animals and they eat a lot, each one consuming what would otherwise feed about five hedgehogs. Studies suggest that when badgers exceed a certain population density, hedgehogs are liable to become extinct. That level of badger abundance was already exceeded about 15 years ago in many parts of Britain and since then badger numbers have increased by at least 10%. No matter how much we may like and enjoy badgers, it is an inescapable fact that more of them must mean less of something else. So the hedgehog’s situation appears pretty bleak, which is all the more reason why we should do whatever we can to support these animals. Rescuing sick and injured hedgehogs does help, and my studies have shown that even inexperienced juveniles have a high chance of survival when released after a period in care. Adults manage very well indeed even if they are released into unfamiliar places. So, the hundreds of carers who rescue injured hedgehogs and underweight babies (in the autumn) are helping to compensate a little for all the many threats that these animals face in our modern world. But we need to do more. We should start by removing unnecessary hazards from our gardens. For example, although hedgehogs can swim, they cannot escape from smooth-sided plastic garden ponds. So, fit an escape ramp or provide some chicken wire that will enable them to climb out. Avoid using slug pellets, or if you must, then deploy them safely under a raised paving slab. Ensure there are adequate holes in the bottom of your fences so that hedgehogs (and frogs, toads, shrews and all the rest) can move easily between gardens and have a greater foraging area available to them. Try to ensure that there are places to hibernate during the winter and lots of leaves with which to build a protective winter nest. All these suggestions are spelt out in more detail in my book, which has been in print since 1983 (The New Hedgehog Book, Whittet Books, 2014). More details are available on the website (www.hedgehogstreet.org), where more than 30,000 people have signed up to become Hedgehog Champions by creating hedgehog-friendly gardens. Why not join them? Dr Pat Morris

Trans. Suffolk Nat. Soc. 51 (2015)

The Hedgehog's plight  

Pat Morris

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