Why do moles need to produce so many molehills?

27 January
15 February

For one reason only, which is to get soil out of their tunnels. Moles are the only perfectly subterranean mammals and their tunnels are two things: their home and their larder. They build territories that vary enormously in size but can consist of 1000m of tunnel covering an area of about 40m x 40m.

Moles feed in two ways. They dig and hit worms and other invertebrates underground or at grass roots level, or else the worms migrate through the soil and fall into the tunnels and the mole comes along and picks them off. They have to get the soil out of the tunnels so they dig shafts to the surface and push the soil above ground. That is how molehills are created.

Because they live underground, where oxygen levels are very low, moles have specialised haemoglobin, which is the protein in blood that carries oxygen. They are totally solitary creatures, living alone except for when males and females get together – very briefly indeed – in order to mate.

"Moles are terrifically strong and can push out 20 times their own weight in soil"

Moles will dig on average for four-and-a-half hours per day. It’s such energy-intensive work. Even to dig a metre will take them about an hour. They are terrifically strong and can push out 20 times their own weight in soil – far stronger than a human weightlifter, for example.

There are around 31 million moles in the UK. They are not evenly spread: their preference is for very rich loams, nice deep soils with lots of earthworms. They don’t like thin, stony soil – it doesn’t have the prey they need, nor the soil structure to maintain their tunnels. They will occasionally come above ground, in order to find nesting materials, and they can also swim up to 100m. Nor are European moles actually blind – they just have very small eyes.

Naturally, the molehills mean that moles are gardeners’ bête noire, and people try all kinds of ways to get rid of them. They use repellent smells, or put holly or bramble in their runs. They put milk bottles in the runs so the wind blows over the top, causing a vibration to try to disturb the mole, or even children’s toy windmills, for the same reason. None of these things work.

Gardeners used to get rid of moles by putting chemicals such as sump oil or creosote into the soil. That is illegal now. So is strychnine, which is a terrible poison. In fact, from the 1950s until 2006, strychnine was banned for everything in Britain except for killing moles, which was outrageous – the poor things died such horrible deaths. So now people fall back on trapping moles, which is the most effective way of getting rid of them. Not that I'm advocating it.

"Moles are one of nature’s plucky little underdogs"

Whenever badger culls are mounted there is a huge public outrage but people don’t care so much about moles. They haven’t got such a good PR machine. It’s a shame, because they are pretty wonderful little creatures with so many admirable characteristics. They work incredibly hard and have these interesting, business-like little lives.

I suppose moles are one of nature’s plucky little underdogs, which has always appealed to me. They do a lot of good: they turn the soil, provide germination for rare herbs and eat pests and insects underground. They don’t even make that many molehills in the summer. If only gardeners could stop minding, and just remove the molehills with a spade, or rake them over, that would be great – because moles deserve a bit of respect.

Rob Atkinson is the author of Moles (The British Natural History Collection), Whittet Books, 2013, £14.99

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