Despite being common and widespread in England, Wales and, to a lesser extent, Scotland, moles are rarely seen. Instead, their presence is belied by the fruits of their labour, which typically take the form of spoil heaps above their tunnel entrances that we call "molehills". Despite their subterranean activity making them a pest of gardeners and farmers, moles help aerate and loosen soil, which promotes plant growth, and eat many species of invertebrate that are known to damage plants and commercial crops. The soil turned out of their tunnels into the molehill also make excellent potting soil. Indeed, moles were known as Moldewarps ('earth throwers') from at least the 1300s, although today the term has come to mean a sneaky or underhand person.
That which follows is a summary of the natural history of the European mole.
The European mole at a glance
Size and Appearance: The range is 5 cm to about 20 cm (2-8 in.) in length, but the average is closer to 12 cm (5 in.). Weight is highly variable according to sex and season, varying by as much as 20 g (0.7 oz.) through the year. Weight tends to range between about 60 and 140 g (2-5 oz.), with the average 80-100g (~3-3.5 oz.). The tail is short (3 cm), the hind feet are relatively small but with comparatively long claws, while the front feet are disproportionately large and spade-like, used for digging - indeed, moles essentially "swim" through soil. The nose is fairly long and terminates in a somewhat pig-like snout, the eyes are tiny (1 mm diameter), as are the ears that present as small ridges under the fur. The fur isn't "slanted" as it is in most mammals, so it can be brushed forwards or backwards, allowing the mole to move in either direction in tunnel system. Stiff, highly sensitive hairs cover the head, feet, and tail, monitoring vibrations and wind disturbance in the tunnel system and alerts the mole to the presence of food or danger, as well as to sections in need of repair. Internally, the mole is well adapted to subterranean lifestyle where oxygen levels are 15% lower and carbon dioxide 10-fold higher than at the surface; lungs are enlarged to fill rib cage, while the blood has twice the erythrocyte (red blood cell) density of other mammals, allowing for enhanced oxygen transport.
Colour: The fur is usually velvety dark grey or grey-black, but various colour morphs have been recorded, including white, cream, apricot/yellow, tan, and piebald animals. A 16 cm (6 in.) albino specimen is preserved in a museum in Gers, Midi-Pyrénées (France). Moults occur three times per year, depending on latitude.
Distribution and Habitat: Widespread throughout much of Britain and Europe in deciduous woodland, grassland, and farmland, although they're rarely seen. Rare in conifer forests, moorland, flooded fenlands, and in agricultural fields that are regularly ploughed (this destroys the tunnel network, driving moles to the field periphery). Data from MoleWatch, a now-terminated project run by the People's Trust for Endangered Species that collected data on molehill distribution in 2008, suggested they were reasonably widespread in England, although there were notable absences around some major conurbations (e.g., London and parts of Thames Valley). Records in the NBN Atlas as of July 2024, largely confirm the MoleWatch distribution, with noticeably sparse distribution in Devon, Wales, and Lincolnshire, and "hotspots" in Norfolk, Cheshire, Derbyshire, and Staffordshire. Moles are absent from Ireland, and while we know they're present in Scotland there are few data to confirm distribution, although the NBN Atlas data show many more records in the east than west. Distribution extends from Britain east into central Russia, north to southern Sweden and Norway, south into northern Spain, northern Italy and much of Ukraine. They are apparently absent from most of Spain, Portugal, most of Italy, Greece, and southern Ukraine.
Longevity: Typically less than a year, although what limited data we have (mostly from Georg Heinrich Stein's studies in Germany, published in 1950) suggest up to three years is probably the maximum in the wild, although Grzimek's Animal Life Encyclopedia (1990) gave four years as the maximum life expectancy. Several sources mention five to seven years, but do not provide a references. Rob Atkinson, in his hugely engaging 2013 book Moles, for example, wrote:
"An undisturbed population of moles contains 60 per cent moles in their first year, 20 per cent in their second, 10 per cent in their third; 5 per cent in their fourth, 3 per cent in their fifth, 2 per cent in their sixth and less than 1 per cent in their seventh."
Sexing: Very difficult, even in the hand. Males are typically larger than females, i.e., longer and heaver, although not by much (ca. 5%). Females have four pairs of mammae (nipples) running from the forward part of the chest to the groin. Sexual separation generally requires dissection owing to both sexes having very similar-looking genitalia with differences in size to the order of a millimetre, and the males' testes being internal. The visible portion of the penis is ca. 7 mm long, but the female has a similar-looking-but-fractionally-smaller "urinary papillae" (actually a penis-like clitoris) - this may be part of the root of the old country adage that all moles are female until the spring, when half become female (see: Reproduction). The distance between the openings can be used to separate sexes outside the breeding season, with practice.
Activity: Moles spend most of their lives underground, patrolling tunnels roughly every four hours looking for food and intruders. More time is spent above ground in summer, looking for territory, food, bedding, and females, and by juveniles dispersing from their natal territory. Indeed, juveniles seem to be encountered above ground more often than adults (perhaps explaining their predominance in predation and road collision data), although flooding may drive adults above ground during the autumn and winter months. Despite being built for a subterranean life, moles are surprisingly quick above ground. Moles are active throughout the year, even digging tunnels in snow, with activity peaking during the spring breeding season. Triphasic activity patterns have been reported in the literature (i.e., three activity periods, each ~4 hours, per 24 hrs) for much of the year, decreasing to two periods during breeding season as males search for mates. During his studies in Oxfordshire, Rob Atkinson found mole activity generally peaked between 01:00 and 02:00, 08:00 and 09:00, and again 16:00 and 17:00. Summer droughts appear to "smooth out" the typical activity peaks, with moles having to spend longer searching for food and water. Territory defence and tunnel extension accounts for just over half of their activity. Females appear most active when suckling young. Moles lack any apparent ability to store fat, so cannot hibernate during winter.
Dens: Lives in a network of tunnels that it expands throughout its life at up to 20 m (66 ft. per day). Earth displaced during network renovation/repair and expansion is pushed to the surface, creating "molehills". Molehills are more than just spoil heaps, however, and appear to direct airflow into the tunnel system, ensuring there is a steady breeze throughout the network even on calm days above ground. This air movement apparently helps transfer information about food or intruders in the tunnels or damage to the network. If the molehill is cleared, leaving the opening clear, it will be quickly plugged. Large chambers off the main tunnels are lined with vegetation and used as resting sites ("nests") and some of these are reinforced to provide additional protection from predators and the elements (e.g., conserve heat during winter) - we know very little about these "fortresses". Some authors have calculated that a mole may move 6 kg (13 lbs.) of earth every 20 minutes while excavating tunnels. Tunnel systems may extend beyond 1 m (3.5 ft.) down, particularly during protracted hot, dry conditions under which earthworms retreat deeper.
Territory: Moles are highly territorial and tolerate others only during the breeding season, although the same individuals may overlap in their peripheries of their ranges. Males holder larger territories than females (often twice the size), the core areas of which are defended vigorously, while some overlap may occur in peripheral tunnels. Aggression may be reduced by neighbouring animals using different tunnels at different times, and some studies suggest that only about one-third of the territory will be used in any period of activity. The size and shape of a territory is highly variable and dependent upon prey availability and soil conditions. On average, however, a male's territory in summer may extend over ca. 3,000 sq-m (0.75 acre) compared with perhaps 8,000 sq-m (2 acres) in winter. Female territories appear stable throughout the year, covering 1,300 to 2,100 sq-m (0.5 acre). Invariably, where invertebrate density is high, territories are smaller and population densities higher.
Diet: Moles feed predominantly on earthworms (some studies suggest the diet consists of 90% worms in winter, 50% in summer), opportunistically taking insects (e.g., centipedes, millipedes and larvae) and molluscs. There are records of them preying on small mammals -- i.e., mice and shrews -- as well as snakes and lizards, small birds, frogs, and other moles (carrion?). There's some suggestion that their saliva is toxic, used to paralyze worms that are later cached (common in spring and autumn) -- one cache contained just over 1,500 worms. Food appears to be mostly sourced from tunnels, which act as a food trap (i.e., invertebrates fall in), and excess is earth removed from prey by pulling it through the claws. Air disturbances in the tunnel as prey enters and moves around trigger the vibrissae on the tail, head, and feet. The snout is also covered in thousands of tiny touch-receptors called Eimer's organs, named after German zoologist Thomas Eimer who described them in 1871, that are very heavily innervated (i.e., the roughly 5,000 organs on nose are associated with 105,000 or so nerve fibres), making the snout highly sensitive to air currents. Moles also have a well developed sense of smell and can apparently detect earthworms through 8 cm (3 in.) of clay. Moles have a very fast metabolism that requires it to eat at least every 6 hours, consuming 40-50 g (~ 1.5 oz.), or ~25 worms, per day. Vegetable matter is rare in the diet, although a study from Berlin found Ascomycota truffles in the stomachs of 30% of moles caught in pine forest.
Reproduction: A promiscuous species, with a brief breeding season running from February to May and a short oestrous (estimated at less than 24 hours). The male's reproductive system begins reactivating from a summertime hiatus during the autumn, and development occurs rapidly during January, the prostate and testes reaching their maximum size by March. Country lore held that all moles were female until the spring, when half turned into males, suggesting they were hermaphrodites, and there is an element of truth to this -- they're "true" (but not "functional") hermaphrodites. Females possess ovotestes (i.e., their reproductive organs are divided into both testicular and ovarian tissues); the ovarian tissue functions normally, resulting in pregnancy, but unlike in functional hermaphrodites the testicular tissue doesn't produce sperm, it only produces testosterone, which presumably accounts for the territoriality/aggression they exhibit being proportional to that of males. Outside of the breeding season, the testicular tissue remains active, while the ovarian tissue and uterus regresses. In the breeding season this switches, resulting in a reduction in testosterone and reactivation of female organs, including the development of an opening between the urinary papilla and anus to allow mating. This opening heals over after conception, although one 1996 study found a small number of females with a vaginal opening and uterine vascularisation (suggesting oestrous) in September. With the female's circulating testosterone reduced, the male can enter her tunnels and mate with her -- the number of females in oestrous peaks during March. Radio-tracking suggests that males may move at least 200 m (650 ft.) in search of receptive females, and we know that a single male will mate with several females, but we know nothing about mate choice or polyandry among females. We also have very few data on courtship behaviour, although males appear to mount females from behind.
As the birth approaches the female will dig and line a nest chamber - typically only one is used, but she may have three or more and move young to if disturbed. The average litter size is four young, but the range is two to seven, born after a gestation of around 30 days. Births range from about mid-April until late June. In the week prior to parturition, the female's mammary glands thicken and spread as she starts to produce milk. Pups weigh about 3.5 g (0.1 oz.), are about 3.5 cm (1.4 in.) long and furless at birth, but grow remarkably quickly, which is presumably a testament to the quality of the milk, although we have no data on milk composition in this species. Indeed, by the time the eyes open at about three weeks old the pup will weigh about 60 g (2 oz.). Fur growth complete by 14 days old. Pups begin leaving the nest at about one month old as they start to explore, initially venturing only a few metres from the nest (often with siblings) before returning: this distance increases over subsequent days/weeks. Pups are weaned at 4-5 weeks, independent by 6 weeks, and sexually mature at around 10 months. Dispersal typically happens soon after weaning (i.e., at 5 or 6 weeks old), but can depend on environmental conditions -- drought may cause early family breakdown, while pups may not disperse until mid-August under bountiful conditions. Only the female demonstrates parental care and the male plays no further role once mating is complete.
Behaviour and Sociality: Moles are solitary by nature and likely only tolerate the presence of others during the breeding season. Some trapping observations suggest, however, that common runways may be used under certain circumstances, such as migration. Presumably, a shift in the phases of activity may allow a temporal offset to promote coexistence (i.e., neighbouring moles use the same tunnels at different times). Moles make various noises, including squeaks and a shrill twittering while fighting and a soft twittering (described by some as a "purr") while feeding or exploring. The species has a pair of anal glands (erroneously interpreted as "preputial glands" by some earlier authors owing to their position), composed of both apocrine and sebaceous cells, just beneath the skin that connect to the urethra an impart scent into the urine and possibly faeces. The volatile composition of the glandular secretion appears to impart information about the individual and their reproductive state. Experiments with captive animals suggest that scent is important both for males locating females and maintenance of territories. Vacant territories can be filled within 24 hours.
Threats: Often killed by predators, but apparently distasteful, moles are frequently discarded. Predators include birds of prey (particularly tawny owls and buzzards), herons, egrets, stoats, weasels, and foxes; some are taken by domestic cats and dogs. Mammalian predators seem more likely to discard the carcass than birds, which eat them (typically tail first) -- this is presumably a reflection of many birds having fewer taste receptors than mammals. Tooth wear leading to starvation appears a major cause of death, as does being killed by vehicles on country roads during the breeding and dispersal periods.
Moles have a long history of persecution in Britain, not least through an association with superstition (e.g., molehills appearing near a house foretold the death of the inhabitants), and have been hunted and/or persecuted since at least Roman times, although they're no longer widely hunted for pelts. Most modern persecution occurs as garden/agricultural pests, particularly on livestock farms where it can still be common to see significant numbers of moles hung on barbed wire fences. Some farmers argue that stepping into molehills can result in horses or cattle breaking legs, although one former keeper at Whipsnade noted that molehills were common in their ungulate paddocks and never caused injury. Similarly, I've heard reports that molehills can expose livestock to soil borne Listeria, either just by exposing the soil or by contaminating silage bales with soil, while others counter that spoiled or mouldy hay/silage is more likely from deficiencies in the process. European moles are not considered endangered, although true numbers and distribution remain tentative. An estimate in 1995 put UK population at around 31 million, and a more recent (2018) review suggested this had risen to about 41.4 million, but this was based on increases in range since the earlier survey and confidence in the number is low.
Benefits: Moles consume many species that gardeners consider pests, while excavated soil makes good compost. Evidence from the Swiss Alps suggests that moles may aid the colonization and spread of Water voles (Arvicola terrestris) in grassland habitats.
Bibliography
Atlas of the Mammals of Great Britain & Northern Ireland - by Multiple Contributors
Pelagic Publishing
-- 2020
-- ISBN: 978-1784272043
Britain’s Mammals 2018: The Mammal Society’s Guide to their Population & Conservation Status - by Multiple Contributors
The Mammal Society
-- 2020
-- ISBN: 978-0993567339
Collins Field Guide: Mammals of Britain and Europe - by David MacDonald and Priscilla Barrett
HarperCollins Publishers
-- 1993
-- ISBN: 978-0002197793
Fauna Britannica - by Stefan Buczacki
Hamlyn Publishing
-- 2002
-- ISBN: 978-0600598671
Mammals of the British Isles: Handbook, 4th Edition - by Stephen Harris and Derek Yalden (eds)
The Mammal Society
-- 2008
-- ISBN: 978-0906282656
The natural history "bible" covering all British mammals with detailed coverage of their biology, behaviour, ecology and taxonomy written by experts in the field and referenced to the primary literature.
Mole. A Life Underground - by Sue Wallace
Independently Published
-- 2020
-- ISBN: 979-8653091513
Moles - by Rob Atkinson
Whittet Books
-- 2013
-- ISBN: 978-1873580868
Nick Baker’s British Wildlife: A month by month guide - by Nick Baker
New Holland Publishers
-- 2003
-- ISBN: 978-1845171131
Silent Fields: The long decline of a nation’s wildlife - by Roger Lovegrove
Oxford Univesrity Press
-- 2007
-- ISBN: 978-0199548156
Simon King’s Wildguide - by Simon King
BBC Books
-- 1994
-- ISBN: 978-0563364962
The British Mammal Guide - by Steve Evans & Paul Wetton
Isabelline Films
-- 2015
-- ISBN: N/A
The Encyclopaedia of Mammals - by David MacDonald (ed.)
Brown Reference Group
-- 2006
-- ISBN: 978-0199206087
The Life of the Mole - by Gillian Godfrey & Peter Crowcroft
The Museum Press
-- 1960
The Mole - by Kenneth Mellanby
HarperCollins Publishers
-- 1971
-- ISBN: 978-0002131452
The Mole - by R. David Stone
Shire Natural History
-- 2009
-- ISBN: 978-0747801719
The Natural History of Moles - by Martyn Gorman & R. David Stone
Christopher Helm, London
-- 1990
-- ISBN: 978-0747012146
The New Amateur Naturalist - by Nick Baker
HarperCollins Publishers
-- 2004
-- ISBN: 978-0007157310
The Wildlife Trust’s Handbook of Garden Wildlife - by Nicholas Hammond
Bloomsbury Natural History
-- 2014
-- ISBN: 978-1472915863
UK Mammals: Species Status & Population Trends - by The Tracking Mammals Partnership
JNCC/TMP
-- 2005
-- ISBN: 978-1861075680
Urban Mammals: A Concise Guide - by David Wembridge
Whittet Books
-- 2012
-- ISBN: 978-1873580851
Urban Wildlife - by Peter Shirley
Whittet Books
-- 1996
-- ISBN: 978-1873580233
Wild Animals of Britain & Europe - by Helga Hofmann
HarperCollins Publishers
-- 1995
-- ISBN: 978-0007627271