Our Wild Things columnist Eric Brown reviews a new book naming badgers, vehicles, slug pellets and postmen among chief enemies of hedgehogs and suggests several actions to stop the decline of these popular, spiny creatures.

Hedgehogs are surely one of Britain's most invisible mammals. Ask yourself when you last saw one of these prickly little creatures alive and if you can remember at all the answer is likely to be not for years.

In my own case it would be on a trip to Norfolk more than a decade ago.

Hedgehogs are clandestine creatures of the night, preferring to keep themselves to themselves even if you are fortunate enough to have them as garden visitors. There's good reason for their secretive nature. It seems they have more enemies than Julius Caesar or Attila the Hun. A new book by conservation research scientist Tom Moorhouse reveals some of the many dangers faced by hedgehogs.

Badgers are probably their number one living enemy. The clever ones employ a method of avoiding those nasty hedgehog spines by continually rolling the creatures over to expose soft underflesh with their formidable claws. Then it is hedgehog dinner.

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Even if hedgehogs manage to avoid being rolled they lose out anyway as the mighty badgers outmuscle them to scoff the worms, caterpillars and beetles they rely on for food.

Foxes will also eat hedgehogs but are less adept at avoiding the spines.

By far the greatest danger to hedgehogs comes from humans (boo). Mr Moorhouse maintains that during the spell hedgehog numbers are thought to have declined most steeply, motor vehicles increased sixfold. Hedgehogs just don't get along with the car, the lorry, bus and tractor. The sad sight of a squashed hedgehog on a road is the most likely scenario for seeing one nowadays.

Even postmen are listed among hedgehogs' worst enemies. The elastic bands they discard from bundles of letters resemble worms to a hedgehog and are often eaten with fatal consequences.

Then there's November 5, the most dangerous day in the calendar for urban hedgehogs. Around that time they seek shelter for the winter. What could be more inviting than a nice pile of wood, bramble and old carpet to keep you warm ? If people fail to check their bonfires before lighting, it's often roast hedgehog.

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And of course slug pellets are another enemy. They can poison hedgehogs who think they are food. If you can attract hedgehogs to the garden you won't need pellets as hedgehogs will eat the slugs.

Agriculture must also take responsibility for hedgehog decline. One unfortunate was located squashed upside down into farm mud with the imprint of a cow's hoof indicating the guilty party.

Sixty per cent of Britain's one million kilometres of hedgerow were removed during the 40 years after 1940. Hedgerows are hedgehogs' favourite habitat. There is a glimmer of hope here as we slowly realise errors made in the rush to feed a post-war generation and start replacing hedges.

Just how much hedgehog numbers have plummeted is open for debate. Mr Moorhouse spends much of the book debunking hedgehog survey results. That includes the one which produced the generally accepted figure of a fall from 36 million in the 1950s to around 550,000 today. This figure, says the author, was arrived at in slightly casual and unscientific manner. Mr Moorhouse casts doubt on its accuracy and also questions numbers in subsequent surveys. The fact is hedgehogs are so difficult to survey that there are no totally reliable, up-to-date population figures.

As Mr Moorhouse points out the best evidence is of our own eyes which brings us back to the question of when you last saw a hedgehog.

Luckily we can help these spike-balls voted Britain's favourite mammal in a 2016 poll. First, if you are putting out bread and milk for hedgehogs please stop. It upsets their stomachs. Provide meat-based dog or cat food instead.

Second, create holes in your garden fences - after consulting the neighbours - to allow hedgehogs access during nightly rambles of up to 20 miles. Third, consider providing a hedgehog home in your garden. They are available from the RSPB. Also pick up those rubber bands and stop using slug pellets.

Act soon before it is too late for the hedgehog.