A marked decline in the number of the UK's hedgehogs has led to wildlife experts to add them to the Biodiversity Action Plan for threatened species. In this week's Green Room, Hugh Warwick argues that we have become bad hosts to the once frequent garden visitor.
Hedgehogs are pretty robust critters. In some form or other they have been around since the beginning of mammals; early versions were nipping at the heels of the departing dinosaurs.
As we manicure our green space... we drive hedgehogs and their food out into a wilderness with little sign of comfort
They have survived ice ages, outlasted mammoths and sabre-toothed tigers and even managed to form a symbiotic relationship with their arch-predator, humans.
So why do we suddenly have to worry about the plummeting number of hedgehogs in the UK?
Each year there is a slightly ironic research project to determine the population of animals, called Mammals on Roads. It uses volunteers to drive stretches of highways, counting the number of corpses along the roadsides.
Co-ordinated by the People's Trust for Endangered Species (PTES), it has obvious benefits as far as gathering data on hedgehogs is concerned.
By comparing year-on-year figures, this technique has revealed a staggering drop in hedgehog numbers. Over the UK as a whole there was a 20% decline, and in some regions, it was as big as 50%.
In response to this, the PTES and the British Hedgehog Preservation Society launched HogWatch.
Using some of the best brains in the business - namely Dr Paul Bright and his colleague Anouschka Hof from Royal Holloway, University of London - we set about trying to find answers to the problems presented by the road kill data; primarily, what was causing this dramatic decline?
The first part of the project was to build a map, employing a host of amateur naturalists.
Nearly 20,000 people answered our call for sightings, and more importantly absence of sightings, because in order to build a useful map we needed to know not just where the hedgehogs were, but also where they were not.
The great response confirmed the place of hedgehogs in the nation's affection. It also showed that there was an unexpected split down the country with more hedgehogs being seen in the east.
So what are the reasons for the decline? Although the project is only half way through, we are already beginning to get an idea as to some of the main causes. Principal among these is habitat fragmentation.
A happy hedgehog habitat is one in which there is just the right combination of shelter and food. Despite the defensive prickles, hogs do like to keep to the edges.
As developments get denser, the wildlife corridors vanish.
In fact their natural home is woodland edge - something that we have recreated in abundance - hedges. Or at least there used to be plenty of hedges until the lunatic fashion of ecological destruction took hold.
But here is an interesting thought. There used to be no hedges. When the UK was largely forest, hedgehogs would have had to make do with clearings for their favoured climes.
They must have loved it as agriculture set in and hedges became the norm. But nothing stays the same; when the hedge-killers did their worst, the hogs sought refuge in suburbia as their homes were grubbed up and the farmers were paid for the havoc they wreaked.
In suburbia, humanity had created hedgehog heaven, a network of green spaces, complete with cover and food.
This is one of the reasons why hedgehogs are so popular; they are like the perfect house guest. We know they are there, but they make no fuss; they also help out around the place, cleaning up the lettuce, chomping mini-beasts that infest our beds and borders.
So what is making our guests feel so unwelcome? The refuge of suburbia, sanctuary from the ecological desert that so much of our industrialised countryside has become, is also turning hostile. And this is one of the reasons why hedgehogs are in decline.
Tidy gardens are not a hedgehog's favourite habitat
As the roads become busier, so they also become impassable. As developments get denser, the wildlife corridors vanish.
As the gardens get turned into extensions, either literally or through decking and patio heaters, more habitat is lost.
As we manicure our green space, nuking bugs and napalming weeds, we drive hedgehogs and their food out into a wilderness with little sign of comfort.
But it does not need to be like this; hedgehogs are important - we have proved this time and again.
The Environment Agency wants a new icon and the vote goes to the hedgehog. Whether it is greetings cards, tea-towels or cuddly toys, hedgehogs are everywhere.
So the hedgehogs can now help us to help them - if we realise the impact that our lifestyles are having on such a charismatic and well-loved beast, perhaps we can halt the out and out destruction of all that is green.
If you want hedgehogs in your garden or park, see that they have what they need: shelter and food. Learn about hedgehogs so that you can begin to think like them.
The essence of empathy is in that level of understanding. Start to try and appreciate your local area with the eyes, nose and ears of a hedgehog.
What are going to be the obstacles to a hedgehog haven? Then see if you can start to remove them.
Hugh Warwick is a freelance writer and ecologist. His book, The Hedgehog's Dilemma, will be published in October 2008
As part of the book, Hugh is collecting anecdotes about hedgehogs from all over the world. If you have had an interesting hedgehog story you would like to share, please email him at: email@example.com
The Green Room is a series of opinion pieces on environmental topics running weekly on the BBC News website
Do you agree with Hugh Warwick? Are we driving hedgehogs out of urban areas? Are new developments and tidier gardens depriving them of valuable food? Or are they little more than pests that eat the eggs of threatened birds?
I think that hedgehogs are amazing animals. The other day I was walking along a quite but sometimes dangerous road, and I found a hedgehog asleep. We made sure that he was alive and OK then rolled him into a nearby bush.
Charlotte Cook, Durham, UK
I am fortunate enough to live in a beautiful and unspoilt area of the U.K. Cornwall, in fact on the edge of Bodmin Moor. You would think that with all the woodland & hedgerows and large tracts of wild undisturbed countryside hear we would have abundance of hedgehogs. But sadly thats not the case. I have not seen one in years, & I spent a lot of time out early and late fishing. where have they all gone?.
David Wood, Liskeard
A scientific study about 4 or 5 years ago concluded that through a process of natural selection Hedgehogs had evolved there own green cross code. Hedgehogs that were naturally cautious across roads had a longer lifespan and so were more successful at breeding so surely this study just backs this up?
There are loads of Hedgehogs around me but then there are lots of hedges in my garden and the veggie patch provides a constant source of slugs for them (they also get some cat food if I hear one rustling about in a hedge).
I wholeheartedly agree with Hugh Warwick.I would also like to see a ban on the sale of slug pellets.
sandra bonar, scotlandwell kinross Scotland
We have been visited by hedgehogs for some years, and gave a home to an injured one for a while. Our garden has lots of cover - and loads of slugs! It's suburban, but not so tidy that a hedgehog can't find what it needs. Trouble is, there are fast roads and too many cars around, so they are killed when they leave. Don't think there is a solution to this aspect of the problem; wish there were.
Althea Stevens, Newquay, Cornwall UK
Judging by the daily roadkill, we must have thousands of them here.
Warren Davies, Ramsey, IOM
During the 1950's and 60's we lived in houses with walled gardens; high brick walls, and garden doors that came down to earth level. My mother always had a hedgehog or two as Assistant Gardeners; they were a great help at consuming slugs, and they were soon 'tamed' to come when she took them a treat of a Egg Yolk mixed with a little milk.
For some reason I can still remember some of their names; Quinton Hogg, Spike Milligan, and Simon de Bretton.
My mother always did have a magical touch with any animal; she'd hold them in her hand and rub their soft belly fur and they'd lie there blissfully.
Liz Powell, Ontario, Canada
I've only ever seen 2 hedgehogs in my city, the first was in the middle of the road so i parked my bike to block traffic and walked next to it while it crossed the road, the other was lost in an urban area so I got a box and took it to the park, if their decline is to be stopped people need to stop thinking their superior to animals and go to the effort to make sure they cross our tarmac jungle safely.
Dale Morgan, Swansea, Wales
I'm dubious of estimating a population by road kills. Are we sure hedgehog mums aren't teaching their kids the Green X Code?
It is not the hedgehogs' fault that they have been eating birds' eggs on the Uist islands. I understand that humans introduced them. I am so thankful that Uist Hedgehog Rescue has managed to save many from being killed by moving them to the mainland. We are now into our fourth summer without seeing any hedgehogs in our garden and we miss them so much. They used to be regular visitors but suddenly vanished - not a gradual reduction in numbers but total disappearance.
Jane Tyler, Bath, England
We have a very un-manicured suburban garden and are currently seeing hedgehogs several times most evenings (not the all same one as they are different sizes and we sometimes see two at a time...) We have lived here over 20 years and had never seen any hedgehogs at all until last year, though I suppose they might have been there without our noticing. We always put food and water out in the hope that they will keep coming back.
AlisonC, Wandsworth, SW London, UK
How come the science page is always full of British ecology? Before it was Birds in Britain this or Birds in Britain that, now it is Britian critters this or that. Don't you have more important world science news to report, or are some people sleeping over there?
Jacob Kinnun, Tucson, United States
The big problem as I see it is the redevelopment of 'brownfield' sites in towns: these places, often overgrown and unkempt, were the unsung nature-reserves of the country. Now with the stupid pressure towards ever-higher housing density they're being flattened and built on. I know of several such sites that had once housed populations of slow-worms and lizards - now all they house is another tranche of prototype-slum 'affordable homes' for chavs.
Tanuki, Wiltshire, UK
My husband and I visited Scotland in 2000, staying at Boleskine House on the east side of Loch Ness. At the time we were individual travelers, driving around to see the ancient sites which took us hours away, simply exploring by following our map of the area. We were looking forward to perhaps coming upon (live) hedgehogs as we don't have them in California, but instead were sorely disappointed to find only a few dead ones on the roads. We thought that we would see them alive, all over the place. What a shame that hedgehogs are in such decline! There definitely should be more serious localized, suburban, conservation measures in place to keep such an iconic and loved animal from going extinct.
May , Rancho Palos Verdes, CA
Yes, I agree we need Hedgehogs. They are yet another ecological indicator we would be stupid to ignore. What is good for them is good for us. My garden is a mess, but it has masses of wildlife. The occasional hedgehog included. The grubbing up of greenery in towns is disgraceful, and only adds to flooding, pollution and a bleak vista which encourages lack of respect for the neighbourhood. The authorities need to remedy this fast. A greener neighbourhood is a far more pleasant neighbourhood.
Richard - East London, Ilford
In the late 1970's I lived in a house in Rotterdam that was being overrun by mice. It was that bad that my two cats didn't bother chasing them anymore.. they just let the mice play with them. So I brought in the ultimate weapon in urban warfare against mice: a hedgehog. Within two weeks my house was clear of mice; whether he/she ate them or chased them out I didn't know or care.. it worked. The only problem was that, being nocturnal, it found a place to sleep during the day: inside my bed pillow case, which I promptly forgot most nights. And as I usually went to bed before it got up... ouch.. Small price to pay for a mouse-free house though.
Paul van Poppelen, Gibsons, BC, Canada