Moles

Image: Kókay Szabolcs

The onset of the frosts often brings signs of renewed mole activity, especially on pastureland. One morning it seems that freshly turned molehills are everywhere. There appears to be no pattern to them; an army of excavators has been at work; but if carefully studied it emerges that the heaps usually belong to a single burrow system inhabited by a single mole.

The “moudiewart” is not much of a socializer. Except when male and female briefly meet, of necessity, in the early spring, any encounter between moles usually leads to a fight, often vicious, and sometimes to the death. They are subterranean hermits, irascible and solitary. Their world, just a few inches underfoot, is quite bizarre; and they are wonderfully adapted to it.

Few people have seen a dead mole, never mind a live one, but of those who have, most are surprised by its smallness. A really big buck, so called, is no more than five and three-quarters inches long and tips the scale at something under five ounces.

Yet, for its size, the mole is one of the world’s strongest animals. In just twenty minutes it can evacuate as much as ten pounds of soil, or fifty times its own body-weight. A twelve-stone miner would have to shift four tons in the same period to work at a corresponding rate.

To fuel this tremendous effort, moles have a voracious intake of food, consuming about half their own weight every day. The main item of diet is the earthworm, but other soil invertebrates like slugs and leatherjackets are taken too.

The burrow system serves to trap whatever stumbles into it. The mole makes regular patrols, snapping up food as he finds it. When caught, a worm is seized with the jaws and pulled through the huge forelimbs in a special way, which cleans it of much external dirt and at the same time helps to void the contents of its gut. This done, the worm is either devoured in a matter of moments; or, in some circumstances, bitten in the head, to immobilize it, and stored to be savoured later. A mole’s pantry may contain many worms: the record is 470, weighing almost two pounds!

Periods of frenetic activity lasting about four and a half hours alternate with periods of about three and a half hours in the nest, sleeping it off. The cycle goes on regardless of day or night.

Some foreign species of mole are completely blind, with the eyes not only reduced but actually covered with skin. Our mole has not quite reached this stage. If you blow gently, you can part the plush pile of the fur to reveal tiny bead-like eyes. They can just distinguish light from dark, but probably not much else.

Nor is hearing of great importance. The external ear has gone altogether – it would only get in the way during burrowing – and the internal ear is not specially well developed. Taste and smell are also rather rudimentary.

Of much more interest are the mole’s other senses. It is keenly sensitive to touch, and can detect minute vibrations in the soil. Groups of tactile hairs are found on the chin and muzzle and the tip of the tail. The snout, pink and hairless, is covered with thousands of papillae called Eimer’s organs. These are specially sensitive, particularly when the slightly erectile tip of the snout is gorged with blood.

The function of these Eimer’s organs is not really known. They certainly register subtle changes in touch, and perhaps in smells too. They may also be affected by changes in temperature and infra-red radiation, enabling the mole to “see” in the dark.

Even more remarkably, it has been suggested that Eimer’s organs might also work as “teletactile receptors”, sensitive to minute changes in air pressure. By this means the mole could tell at a distance when it was approaching an obstacle or even a prey animal. The vibrissae may also help the mole to detect compression waves in the air, and certainly warn it of approaching obstacles.

If a mole’s senses are well adapted to the underground life, his anatomy is better adapted still. A mole is a digging machine, a furry bulldozer purpose-built for the job. The whole animal is tube-shaped. Its skeleton is heavily reinforced for attachment of the digging muscles and to allow free rotation of the shoulders, which are powerful and relatively massive. The forepaws are developed into efficient shovels, fitted with strong claws.

Put down on almost any surface but concrete, paving, or asphalt, a mole will immediately dive into the ground. A breast-stroke action is used, frenziedly repeated until the tip of the tail vanishes. Once underground the mole progresses with alternate motions of either forepaw, the other being used, together with the hind feet, as a brace.

In soft earth the spoil may simply be compacted into the sides of the tunnel, but in firmer ground it is ejected at intervals through specially made vertical shafts, and forms the molehills which are the bane of gardeners and greenkeepers. Sometimes, in very soft soil, moles make tunnels so close to the surface that the ridges may be clearly seen.

If he is lucky, a young mole will inherit a tunnel system ready-made, but often as not he has to start, so to say, from scratch. The construction of a complete tunnel system is a colossal task. Without seeking planning permission, tendering for contract, putting up a signboard, or bothering with a starting ceremony, the mole just gets on with it.

The system always incorporates a nest, a spherical chamber lined with hay and leaves. Here the mole sleeps, or if she is pregnant, gives birth to the tiny pink molelets. In places liable to flooding, the nest may be sited in an abnormally large molehill. These big hills, or fortresses, can be a foot high and a yard across.

Once the basic system is dug, it is refined and enlarged with other tunnels, crossing and branching and on a variety of levels. From then on most of the mole’s work consists of keeping it clear of obstructions.

When the weather turns cold, the mole moves into deeper tunnels which might not have been used since the spring. Repairs and alterations produce spoil; and it is this spoil that appears above the ground at the start of frosty weather – as sure a sign as any of the coming winter, and an outward clue that matters proceed in the industrious, hermitic life of the mole.

(Introduction to these pieces; see all)

This is the last of the Natureview pieces suitable for reproduction here. I hope you have enjoyed at least some of them.

Richard