All About Moles

1. A Mole’s Unique Body and Senses

Moles do possess eyes but they are little more than pin pricks that can differentiate between light, dark and close up movement and little more. Their other senses are highly developed and tuned into their environment as they rely on them to feed and survive.

Their coat is normally a dark grey, almost black colour with the texture and feel of velvet. There is no direction or ‘nap’ to it, which enables them to turn any way in their tunnels with the least resistance. They have 2 organs either side of their nose called the ‘Eimers organs’, (discovered by a Professor Eimer) and these and their tails are covered in multiple bristles known as ‘vibrissae’ which are acutely sensitive and they use them to feel their way around their tunnels. The vibrissae also detect the movement of food trapped in the tunnel and monitor air flow, both vital to the mole’s survival.

Moles also possess something called kinaesthetic sense, a form of imprinted memory which roughly translated means they remember every millimetre of their tunnel system. The vibrissae on their nose sense any change to the base or sides of their tunnel and when they are traveling, their tail is held bolt upright and senses any change to the roof of the tunnel. Any change is thoroughly investigated and damage immediately repaired – this is one of the things that makes them so hard to trap.

A moles strength to size ratio is nothing short of extraordinary and their bone and muscle structure is very disproportionate. Most of their muscle and strength is in their front end and their front feet are perfectly designed for digging and breaking up the soil they have dug. They can shift many times their own body weight with every push or pull and can keep this up without stopping. Their back legs have little muscle and their small back feet serve no other purpose other than to propel them along their tunnels and brace themselves when they are digging.

Moles can travel along their tunnels at 2 1/2 mph (a fast walk for a human being) so technically they could cover over 30 miles in a 24 hour period. 

2. Reproduction

Moles lead a solitary existence apart from when they meet, very briefly, to mate in the spring. The males and females are known as boars and sows (like pigs) and the boar has nothing to do with bringing up the young moles, known as pups. 

The sow will find a food rich area to bring up the pups and prior to giving birth can sometimes cache a number of worms (often in excess of 100) by biting the worm in the head which immobilises it as the mole’s saliva contains a type of anaesthetic. These caches are known as ‘mole larders’ and sustain the sow in the days immediately after giving birth. 

Although the sows possess 8 teats an average litter is around 5. After the young moles become independent at around 5 weeks they depart to make their own way in life. If they don’t, the sow will have no qualms about killing them, her solitary gene is that firmly ingrained. Apart from breeding time moles will not tolerate another one in their territory and will defend it with their life, although it rarely comes to this.

3. Surface Runs

Surface runs can occur for 2 reasons, firstly, if the ground only has a shallow depth of topsoil the subsurface rock/stone can make it virtually impossible for the mole to get through. These runs are normally ridged up and will only continue until deeper digging becomes available as the mole is obviously very vulnerable to predation when traveling these runs. Accordingly, these runs are usually travelled along at speed and rarely used for feeding. 

Secondly, at certain times of the year invertebrates and grubs can be living just underneath the surface matter. The most common of these are leather jackets (the larva of crane flies), with the cock chaffer beetle grubs and centipedes also featuring regularly. When this occurs the mole charges around just under the surface with seemingly no direction rarely leaving an obvious tunnel. The resulting damage has the appearance of a badly fitting carpet and can kill large areas of grass as the root systems have been so disturbed and are starved of moisture. Before the grass starts to die the first indication that this is happening is a ‘spongy’ feel underfoot.

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5. What do Moles Eat?

The mole has 44 teeth (the most of any British mammal) and 97% of their diet consists of earthworms. As the worms ascend and descend through the soil layers in their search for vegetative matter and moisture from the surface, they get temporarily trapped in the mole’s tunnels. Moles have such a high metabolism that each one needs to consume nearly its own body weight every 24 hours to survive. It will patrol its tunnels every 4 hours, devouring everything it comes across, after first meticulously cleaning any soil off its food with its front feet. After this 4 hour feeding session the mole will retire to somewhere safe i.e. under a tree, patio, wall, basically anywhere with a solid surface above it, to rest up and digest their food. 4 hours later the whole process begins again, so their life is perpetual, 4 hours on, 4 hours off.

6. What Eats Moles?

The short answer is not much. Their only predator below ground is the weasel which is the only predator small enough to get through their tunnels. A weasel’s presence will be detected by the mole’s vibrissae sensing minute changes to the air flow in the tunnel system as the weasel travels along it (similar to how we feel the change in air flow as a tube train passes along the underground system). The mole’s defence mechanism is to immediately backfill as many tunnels as possible but even then the weasel sometimes gets lucky.

Foxes have a habit of killing moles, urinating on them and then rolling on them but rarely, if ever, eating them. Dogs and cats will dig them out and sometimes catch them above ground but do not eat them as it is believed they have a very unpleasant taste. Badgers will eat them if they ever catch one which is no surprise given they will hoover up slugs with relish! l once witnessed a heron stalk a mole that was working near the surface and subsequently caught, and swallowed the mole in the blink of an eye.

7. How Long do Moles Live?

In ideal conditions a mole will live for 4-5 years.

8. Molehills

The most common and visually obvious sign that a mole is working an area are molehills which can vary greatly in size and quantity. Generally speaking, large molehills close together would indicate that the mole was working at depth whereas smaller molehills reasonably far apart would indicate that the mole was working relatively shallow in easy soil to tunnel through. 

Tunnel depth can vary greatly due to climatic conditions; in freezing conditions or times of prolonged drought the worms will be deep to avoid being frozen or dehydrated and that’s where the tunnels will be. In a mild, wet climate the tunnels may well only be 4-6 inches down. A straight line of molehills can often appear in the spring which is very often down to a travelling boar in search of a sow – these tunnels are often only used once and may well be the last sign of any damage. 

It should be noted that molehills, which upset people so much, are nothing more than fly tipping – the mole is simply getting rid of what it doesn’t need and it is totally oblivious to the mess it is making on the surface.

9. Why Trap Moles?

Apart from the unsightly damage that can be done to lawns and gardens in general (sometimes resulting in a hefty bill to repair) moles are also disliked by farmers because molehills can often contain a soil born bacteria called clostridium. This bacteria can give cattle and sheep listeria, for which there is no cure and one in three cases are fatal. 

On grazing and pastures molehills kill any grass beneath them and weed seeds such as docks and thistles are very quick to take root in the freshly turned soil which in turn cuts down the amount of available grass. Molehills can also reduce overall yield on arable farms by disrupting root systems and starving the plants of moisture. 

Likewise, horse and pony owners are not fans either, if a mole tunnel collapses under an animals foot it can result in an expensive vet’s bill and in some cases even end in the animal having to be put down.