Monthly musings – Mouldiwarp the earth hog

Image courtesy of Wildlifetrusts.org

This sounds like a character from Lord of the Rings but it is actually one of the common names for the only member of the Talpa genus in the British Isles, the common (European) mole.  Mouldiwarp literally means earth thrower and it was the very epitome of this action in the churchyard in my village that led me to consider our view of this subterranean specialist.  The collective noun for moles is a labour which neatly encapsulates their tireless tunnelling work.

For those who wish to understand their biology then the PTES has some interesting facts and figures - Mole - People's Trust for Endangered Species.  They are well adapted to their subterranean life with an extra set of thumbs giving them spade-like paws to dig with and they have more blood and twice as much haemoglobin as mammals of a similar size to compensate for the amount of oxygen in their tunnel system being only a third of that at the surface.  Whilst it is a myth that the European Mole is blind (other mole species are) their vision is poor.  Instead they use their sense of smell and Eimer’s organs to navigate (All about Moles… — Mammal Society).  These organs are located on their snout and provide a keen sense of touch.  They are unique to the Talpa genus.  Another fascinating fact is that their fur is upright so that when they reverse in their tight tunnels, they don’t brush their hairs the wrong way!

But does their reclusive nature mean we under-estimate their contribution to our ecosystem?

A quick search confirmed my understanding that moles are generally regarded as a common pest, and I have recent memory of mole carcasses being hung from barbed wire fences as a visual record of the successes of the local molecatcher.  Many Councils give advice about how to control them given the damage they can cause to amenity and sporting grassland and gardens and farmers like to control them given they can spoil silage grass or impact arable crops by reducing crop emergence. 

But given the focus on soil health, I wondered if they might have role here that is so far not recognised.  It seems that they are remarkably understudied in scientific literature in this respect.  Just making reference to their activity being simulated by the mole plough is insufficient to argue for their benefits so it was with interest that I read this piece - The Role of Moles in the Ecosystem: Separating Myth from Fact

Their tunnelling action can loosen compacted soil and allow air, water and nutrients to penetrate more deeply thereby supporting increased plant health.  This process is called bioturbation. Their activity supports a number of other beneficial soil organisms, not least the earthworm which is often referred to as nature’s plough.  Earthworms are regarded as an indicator of good soil structure as they aid organic matter decomposition and aerate the soil. In addition, decomposition of organic matter in molehills increases microbial activity in the soil. Consequently, moles may be of particular benefit in improving the structure of compacted and/or heavy clay soils.

We have discovered at the Allerton Project that they have a role in helping native wildflowers establish in meadows alongside more competitive species.  This ties in with research that shows that local, small-scale disturbances like molehills may contribute to local environmental heterogeneity by enabling species less adapted to light competition to thrive[1].

Another benefit I had failed to consider was their role in natural pest control.  Moles have a high metabolic rate and can consume up to 70-100% of body weight due to their tunnelling activity. So they eat lots of insects, grubs and earthworms including pest species such as slugs, leatherjackets, cockchafers and carrot flies and can help reduce the spread of insect-borne diseases.

However many of these benefits may be more suited to the garden than the farm scale.  That said we should perhaps be less concerned with trapping moles (unless they are doing obvious damage) and embrace their net positive contribution to the farmland ecosystem – including being a food source for other farmland species such as owls.

And finally, two interesting benefits to molehills.  Firstly they provide a useful and easy source of soil for testing.  Secondly if you sieve the soil from molehills on archaeological sites you can find interesting historical artefacts.  Our demonstration farm in Leicestershire is on the edge of the village of Loddington which now occupies an area away from its original location (due to the plague).  When school children visit, we have got them to sieve the soil from molehills on the abandoned village site and the bits of pottery and clay pipes etc found are now displayed in the Visitor Centre.

Instead of “earth thrower” perhaps we should be calling them “Nature’s Archaeologists”?