I noticed a series of mole hills on my walk today. We don’t get many signs of moles as they have to find land with plenty of worms in, so they help me identify where that land is. I usually gather their beautifully tilled soil and add it to the top soil of my garden, which has a shortage of depth of soil, since it is full of rocks. That also means I welcome the mole in my garden as I have no precious lawn to protect. Yes, some of the roots of my plants do get eaten, so I lose a few plants. But, as my garden is full of prolific cottage garden plants that is no problem either.
I always thought this underground beastie was blind, even eyeless. Now I know so much more since researching this creature, I will share what I have found with you.
The mole rat evolved during the Pleistocene Epoch (around 2.6 million years ago). Europe had about the same climate as it does today. It was wild and untamed, with vast forests, teeming with wildlife. There were huge herds of herbivores hunting for prey, the scene was like Africa today. Amongst the wild animals were lions, cheetahs, jaguars, and hyenas. Around 1.8 million years ago, the climate began to cool down until the Arctic ice cap expanded. The forests died back, replaced by open tundra, killing off the animals which could not survive the colder temperatures. The ‘European’ animals such as bears, wolves, foxes, and lynxes survived along with our little mole rat.
As with all Pleistocene animals they differed across the planet. In the UK we have the European Mole (Talpa europaea). Talpa europaea is found throughout temperate Europe, from Great Britain in the west to the Ob and Irtysh rivers in the east in Russia. It is a mammal of the order Soricomorpha. It is also known as the Common Mole and the Northern Mole.
It has a cylindrical body and is around 12 cm (5 inches) long. Females are typically smaller than males. The eyes are small and hidden behind fur, while the ears are just small ridges in the skin. European moles with white, light grey, tan, taupe, and black fur have all been reported. The nose is bare with the exception of sensory whiskers. They have well-adapted front limbs for digging. The front feet have 5 strong claws and are permanently turned outward. The teeth are designed for the predation of worms and insects, so the upper jaw and lower jaw are full of incisors and molars to do the job. The long snout of the animal is supported by a special bone developed from the plate of gristle which separates the two nostrils from each other.
In a study of the mole eyes it was found that Talpa withdraws when exposed to a flashlight and it can also perform light/dark discrimination tasks. It can identify if its tunnel has been damaged by a predator. The ears, well protected by fur, can pick up a range of low frequencies and it is thought they act as balanced, pressure-difference receivers.
Talpa europaea individuals live solitary lives except during breeding season, and actively defend their territory. European moles are nocturnal, hunting prey and remaining active only at night. Moles usually have three periods of rest and three periods of activity every 24 hours.
Mating occurs during a short breeding season in the spring (March to May). Gestation lasts four weeks. The young are born around mid to late April. Usually there is a single litter per year. Each litter has two to seven young, born blind and hairless. The mother nurses her young for about a month. The breeding nest of the female is usually located under a smaller soil mound than that of the main nest and has fewer galleries. Fur starts to grow at 14 days, and eyes begin to open at 22 days. Talpa europaea young grow rapidly and reach their adult size in about three weeks. The young begin to leave the nest at 33 days, and disperse from their mother’s range around five or six weeks after birth. Moles are sexually mature during the breeding season in the spring following birth. At five or six weeks after birth, the young disperse above ground to find their individual territories. This is the part of the mole life cycle at which they are most vulnerable to predators.
At this time of year, with the weather getting colder,the moles build their burrows deeper in the ground to find warmth. However, they do not hibernate and remain active throughout the winter.
Female and male moles have different systems of constructing burrows. Females build an irregular network, where males tend to build a long, straight tunnel with others branching off of it. European moles are known to build “fortresses,” structured mounds containing more than 750 kg of soil at times. Internally, the fortresses contain one or more nest chambers and a network of tunnels.. The nest consists of an enlarged section of the burrow, filled with dry grass or dead leaves which fill the nest chamber. The nest has no regular entrances and if used in successive seasons then it will be replaced by another one built on top of the old one. The leaves are connected from the surface by the mole pushing its head through the roof of shallow runs, seizing any within reach and dragging them down. Moles injure the front end of worms to the point that they cannot crawl away, then store them in the nest until needed. The speed with which the mole can get itself below ground is astonishing. A rooting action with the head and snout along with some tearing actions of the front feet, get the head and shoulders down, then with two or three strong heaves the rest of the body follows.
Here is a description of the burrowing technique of this amazing creature:
When it burrows near the surface where the ground is loose, much of the earth is not thrown out but compressed into the sides and roof first with one fore foot then with the other. The roof being slightly raised causing a surface ridge that marks out the course of the burrow. When digging deeper then the feet are brought forward on each side of the snout alternatively and the earth is pushed, with the help of the hind feet, back behind the body. When a plug of loosened earth has accumulated behind the mole, it performs a kind of cramped somersault which turns it around and begins the soil to the nearest up shaft by holding one forefeet in front of itself and walking on the remaining three legs, changing its pushing foot every now and then. The powerful muscles of the shoulders and fore limbs allowing the mole to push a load of soil that weighs much more then the mole itself. The soil that is pushed up the up shaft creates the typical mole hill with the latest being pushed out through the centre and spilling out over and cascading down the sides.
Despite their subterranean and solitary lifestyle, these moles seem to be aware of the presence and behavior of their neighbors. Moles usually remain within the confines of their own tunnel system except during mating season. However, experiments have shown that if a mole is removed from its territory, neighboring moles will rapidly take over this area. If two moles encounter each other during a time other than the breeding season, a fight usually occurs, and this can be savage. But moles try hard to avoid one another.
There are three methods used by moles for obtaining food. These include 1) digging in the soil, 2) walking through the burrow system, and 3) searching on the surface of the ground. Like many creatures, the daily preoccupation is in search of food. Earthworms are the main target, yet there is no evidence to show they cause a decline in earthworm numbers leaving the land devoid of them.
Moles also eat both larval and adult insects and I find plenty of these when I am digging over the garden, so there is no shortage of food for underground living creatures.
Humans remain the number one threat to moles, however, as they are considered agricultural pests and are actively persecuted. Poison is still one method of killing them in a slow and painful death. Alternatively traps.
European moles are hosts for a number of parasites, including fleas, ticks, and worms. Moles are hosts to the largest British flea and can measure as much as 6mm long. But if we eradicated moles we humans would find many insects which are dangerous to us if they multiply, would overwhelm us.
Of course, just as the soil is aerated by worms, so the mole eats the worms but also aerates the soil. The soil benefits from the impact of both the insectivore and the great builder, the earthworm – a builder of fertile topsoil, itself the sustainer of all civilization. A subject of a later blog to be sure.