Deft digger in a velvet jacket
With its powerful, spade-like paws and sleek, dark coat, the mole is the master excavator of an underground network of tunnels
AT FIRST, THE only sign of life is a tiny movement breaking the surface of the small mound of fresh earth in the centre of a grassy field. A few seconds later, the movement resolves itself into a snout, long and pale pinkish brown in colour, with two prominent nostrils at the end. Then, two large front legs appear; again, pinkish in colour, with sharp claws. Finally, the creature’s head emerges: rounded, covered in short, dark brown fur and apparently eyeless. A mole has briefly ventured above the ground: a rare event in this elusive mammal’s life. Yet, almost as soon as it does so, it retreats back into the safety of its subterranean lair.
Moles live almost the whole of their lives underground, in what is known as a ‘fossorial’ lifestyle, from the Latin word for ‘digger’. Even though many other British mammals, including badgers, voles and shrews, also do this, moles are by far the best adapted to a life beneath the soil.
The mole is a long, cylindrical-shaped animal,
with dense, velvet-like fur, which often appears black. Their tail is very short, and their most prominent feature is their huge, spade-like forelimbs, which they use to dig the network of tunnels where they spend virtually their entire life. In contrast, their hindlimbs are tiny. The forelimbs also have an extra ‘thumb’, similar to that of the giant panda, which allows them to dig and to grip their prey more easily.
Typically, a mole is between 5½-8½in (14-21cm) long, and weighs between 2½-5oz (70-130g). Males are known as boars and females as sows, and they are identical in appearance, although males are, on average, slightly larger in size.
Living in the dark
The mole’s eyes are so tiny as to be almost invisible, while its ears are concealed in its dense fur. Like most animals that live mainly underground, moles hardly use their senses of sight and hearing, instead relying on touch and especially smell to track down their prey. That naked snout is packed with tiny receptors, known as ‘Eimer’s organs’, which enable them to find food by touch. They also use anal glands to scent-mark their territory as a warning to any rivals not to intrude.
As a final, crucial adaptation, moles are able to tolerate far higher levels of carbon dioxide, which is the gas exhaled by all oxygen-breathing mammals, than other creatures. This enables them to re-use the air they have already breathed and so survive in their tunnels for longer.
Their fur is so short because this produces less friction as they burrow or move along their tunnels. Unlike most other mammals, the fur can also lie in either direction, so that the mole does not become snagged when reversing or changing its course. Moles keep their coat in good condition by moulting twice a year: once in spring and again in autumn. And they can move at a surprising speed, covering just over 2mph, which is the equivalent, given their size, of a human travelling at approximately 20mph.
Moles create a network of tunnels by digging up to 65ft (20m) in a single day, using their powerful forelimbs alternately to push the soil behind them. Once a mole has dug for a short while, it turns around and shovels the loose earth along the tunnel to a ramp or shaft leading to the surface, then throws it out to create the familiar little piles of soil we know as molehills.
Moles can shift many times their body weight in soil, and in an extreme example of their industry, 2½ acres of pasture were found to contain more than 7,000 molehills.
Each network of tunnels has larger chambers, where the animals can sleep and where the females make a nest each spring. The tunnels may be just a few inches beneath the surface, especially in shallow soils, or extend down by as much as 39in (1m), with a multi-storey system covering an area approximately half the size of a football pitch. In areas prone to flooding, moles may also build mounds on slightly higher ground, known as fortresses, with an interior chamber, where they are able to retreat to if the waters rise.
Locating food
These tunnels are not just a place where the animals live and sleep, they also create a network of ‘pitfall traps’ here, into which earthworms, slugs, insect larvae and various other invertebrates fall, to be caught and eaten by the mole as it patrols its home. The mole’s saliva contains a toxic substance that paralyses their prey, making it less likely to escape.
“The arts of building from the bee receive; Learn of the mole to plow, the worm to weave”
Alexander Pope
The vast majority of the mole’s prey consists of earthworms, which make up approximately 90 per cent of their diet during the winter and half of it in the summer. Before eating them, the mole pulls the worm between its forelimbs to squeeze the dirt out of its gut. Surplus worms are stored in an underground ‘larder’, their heads bitten off so that they are unable to move, though continue to live. More than 1,000 decapitated earthworms have been found in a single cache. These worms serve as a back-up supply to be eaten at a time of food shortages, such as when there is flooding or the ground is frozen during hard winters.
Like other small insectivores, such as hedgehogs and shrews, moles need to feed regularly when awake to replenish lost energy: indeed, they have to eat approximately half their body weight every single day. They do so by interspersing periods of energetic activity, lasting for three or four hours, with similar periods of rest and sleep. Moles are active all year round and do not hibernate.
Preferred habitats
They are found in a wide range of countryside habitats, including woodland rides and clearings, traditional pasture, hedgerows, arable fields and, of course, gardens, where they drive keen gardeners mad by ruining their lawns. Moles prefer clay soils to sandy ones, as the latter are harder for them to create burrows in.
They are found more or less throughout Britain, only being absent from the high tops of the Scottish Highlands and the Northern and Western Isles: Outer Hebrides, Orkney and Shetland. However, along with other widespread British mammals, such as common and water shrews, field and water voles, and the weasel, moles are not found at all in Ireland.
The latest population estimate is that there are more than 30 million moles in Britain: approximately one for every two human beings. The European mole, Talpa europaea, which is the species found in Britain, is one of approximately 50 species found worldwide, on every continent apart from South America and Antarctica.
Breeding call
Moles are solitary creatures for the majority of the year, with each animal living in its own tunnel network, which may house several generations of animals over a period of time. If they do come across another mole, they will fight fiercely, using their claws to drive the intruder away.
The exception to this solitary lifestyle occurs during the breeding season, which extends from February into June. At this time of year, moles will deliberately extend their tunnel network into those of any neighbouring females, finding their potential mates using their acute sense of smell and by uttering a series of high-pitched squeals.
After mating, the female builds a round chamber, lined with grass and leaves, where she will give birth approximately one month later, with the peak of births occurring in late April and May. Unlike many other small mammals, moles usually only have one litter each year, although in southern Britain, they do occasionally manage two.
A typical litter consists of three or four bald, blind and helpless young, weighing just 3.5g. They grow rapidly on their mother’s milk, and, although naked at first, begin growing their fur after two weeks, while their eyes open a week later. They are weaned onto solid food four or five weeks after birth, and, a few days later, they begin to disperse, appearing above ground under cover of darkness and venturing forth to find their own territory.
By three months old, the youngsters are fully grown and resemble their parents. They are ready to breed the following year, which is essential, as moles rarely live longer than two or three years, with the oldest reaching five or six years old. Mortality is especially heavy among juveniles emerging from their burrow for the first time.
Because of their subterranean lifestyle, moles have few predators: stoats can enter their tunnels, while tawny owls keep an eye out for any emerging at night, as do domestic cats and dogs. Moles do harbour a wide range of parasites, including fleas, mites and ticks. Other dangers include being run over by motor vehicles when moving from one area to another, sudden seasonal flooding and, not least, hostility from humans: moles often fall victim to pest controllers, farmers and vindictive gardeners. Not so long ago, men would make a living as mole-catchers, often impaling their tiny victims on thorns or barbed wire to demonstrate their skill or turning their velvety skins into a waistcoat.
The name ‘mole’ is a very ancient one, found in almost identical forms in other Germanic and Scandinavian languages. It derives from a longer word: ‘moldwarp’ or ‘mouldywarp’, which means ‘thrower of soil’.
The most famous mole of all is surely the character in Kenneth Grahame’s celebrated children’s book The Wind in the Willows. But despite this, and the fact that moles are so common, their lifestyle means that they are seldom seen, and perhaps this is one of the reasons why they sadly have not secured a place in the affections of the British nation in the same way as our other wildlife, such as the hedgehog.
However, hidden beneath those molehills, a truly remarkable little creature, about which we have so much still to learn, is hard at work.