By Sarah Mukherjee

Environment correspondent, BBC News



Moles are often seen as pests - but they can be an asset to gardens

Every few inches, the gently undulating, green velvety lawn erupts in a mini-volcano of soil.

It's enough to give most gardeners heart palpitations, but, perhaps ironically, this is the headquarters of Oxford University's Zoology department.

I'm here to talk to two researchers from the People's Trust for Endangered Species, who are starting an online survey and are asking for as many people as possible to help, by molehill spotting around the country.

There is currently no distribution map of the little creatures in the UK; indeed, very little is known about them at all.

As we pick our way (with difficulty) across the once pristine lawn, I learn that they are quite difficult creatures, even for scientists, to research.

Jill Nelson, the chief executive of the Trust, says: "They're nocturnal, which doesn't help."

MOLE FACTS Size: Approx 120mm in length and 110g in weight Habitat: Highly adaptable; can thrive wherever soil is deep enough for tunnelling Habits: Adults alternate between 3-4 hour bursts of activity with similar periods of rest

" If you have them, it's the sign of a healthy garden. The problem is when they disappear."

Not a sentiment many would agree with. Indeed, for a nation of animal lovers, we find hating these tiny burrowers very easy.

Conservationists say farmers traditionally hung them from gibbets in the field to ward off others of their species.

And moleskin clothing became so fashionable in the 19th Century that at one point, 13 million skins were sold each year.

Toxic saliva

But wildlife experts insist moles are a fascinating and vital part of British wildlife

A mole uses its spade-like forelimbs and long, sturdy claws to dig tunnels to create a giant underground trap for invertebrates. Their saliva contains toxins which paralyse earthworms, allowing them to store their still-living prey in specially constructed underground "larders" for later consumption.

Molehills appear when they dig new tunnels to extend their "trap" or search for moles of the opposite sex.

Nature's underground engineers

"At present, seeing a molehill in an area is the only reliable means we have of recording the presence of moles, as they are so rarely seen," says Jill Nelson.

"So mapping molehills will tell us whether at least one mole is present in a particular place."

She adds: "By gathering this information from surveyors across the UK we will be able to produce a distribution map of moles and so judge whether there are areas where they are scarce."

The online Molewatch survey will be active until September.

So next time you see a molehill on the lawn - take a deep breath, and reach for your computer terminal, rather than your shovel.