Erinaceus europaeus
western European hedgehog

Erinaceus europaeus (European hedgehog) is commonly found across Europe and into central Asia. Native to this region, it can be found from the Archipelago of the Azores and as far east as Khazakstan. It is commonly seen in northern Europe, as far as Scandinavia. While it is generally not found south of the Mediterranean Sea, it has been seen in Lebanon. Erinaceus europaeus is also found in New Zealand, where they were introduced in the late 1800s. (Bogdanov, et al., 2009; Brockie, 1959; Mathias, et al., 1998; "Division of Mammals Collections: Search "Erinaceus europaeus"", 2011)

The European hedgehog is found in temperate fields, especially field edges and hedgerows. They prefer drier areas that are not thickly wooded and are occasionally found in scrub and sand dunes. European hedgehogs are commensal and are often found in home gardens, cemeteries, parks, agroecosystems, and other areas that provide appropriate places for hibernation. It commonly occupies elevations from sea level to 2400 m throughout its geographic range. (Beilby, 1791; Burton, 1969; Gaglio, et al., 2009; Hof and Bright, 2010; Johnston, 1903; Lawrence and Brown, 1973; Southern, 1964)

The European hedgehog is a small, round animal with short legs that raise it about 1 inch above the ground. It is plantigrade and has 5 well developed pads and claws on each foot. The first and fifth toes are smaller and weaker than the second, third, and fourth toes. Its coat is white and brown and consists of 3/4 to 1 inch spines, arranged in a radiating pattern, that cover all but its cheeks, throat, stomach, and limbs. Areas not covered in spines are covered in a coarse hair that is yellow-brown in color, though white hedgehogs have been seen. It has an elongated, conical head and snout, a small braincase, a short neck and tail, and well developed eyes and ears. The length of its body ranges from 135 to 265 mm, and males are usually slightly larger than females. The tail is about 20 mm long. (Burton, 1969; Forrest, 1899; Gordon, 1904; Johnston, 1903; Kindahl, 1959; Lawrence and Brown, 1973; Rondinini, 2007; Southern, 1964; Step, 1921; Walker, 1968)

The spines covering the European hedgehog's body have white tips and bases and are covered with alternating brown and black bands. They are hollow and have longitudinal grooves, which decrease their weight. Spines are made of keratin and are attached to the skin in a similar way to hair. Each spine grows from a follicle in the skin that is attached to a small muscle (arrector pili) that is used for piloerection. When a hedgehog rolls into a ball, all of the spines can be erected simultaneously, which is made possible by the panniculus carnosis, a sheet of muscle that covers its back. An adult hedgehog usually has around 5,000 spines covering its body. (Burton, 1969; Forrest, 1899; Gordon, 1904; Johnston, 1903; Kindahl, 1959; Lawrence and Brown, 1973; Rondinini, 2007; Southern, 1964; Step, 1921; Walker, 1968)

Erinaceus europaeus has lacteal and permanent teeth. The permanent dentition features widely space upper incisors such that the lower incisors fit between them. The dental formula for E. europaeus is 3/2, 1/1, 2/3, 3/3. (Burton, 1969; Forrest, 1899; Gordon, 1904; Johnston, 1903; Kindahl, 1959; Lawrence and Brown, 1973; Rondinini, 2007; Southern, 1964; Step, 1921; Walker, 1968)

European hedgehogs are solitary and non-territorial. They begin the mating process when a male encounters a female, at which time the male encircles the female while she lowers her head and makes a variety snorts, grunts, and hisses. If the male is successful in courting the female, he attempts to mount her several times. After numerous copulations, the male leaves the female, and does not provide any parental care to his offspring. He continues to roam alone and attempts to mate with other females until he begins preparing for hibernation. Males and females have multiple mates each season. (Burton, 1969; Hof and Bright, 2010; Rondinini, 2007; Southern, 1964; Walker, 1968)

Erinaceus europaeus begins mating in late spring (April or May) when the the animal emerges from hibernation. Males, which emerge 3 to 4 weeks before females, expand their home range during mating season to increase chances of finding a mate. When a male finds a mate, he circles her while she lowers her nose and becomes audibly defensive. The male may circle for several hours, making several attempts to mount. If the female continually rejects the male, he eventually leaves to find a receptive female. If she accepts him, she flattens her spines and lowers herself to the ground, which gives the male better access. To copulate, a male climbs onto a female's back and uses his teeth to hold onto her shoulder. Gestation last for about 35 days. Females give birth to four to six offspring per litter, and often have two litters per year. The second litter, which is born later in the year, has a reduced chance of surviving winter. New borns are about 3 inches long and weigh 0.3 to 0.9 oz. At birth, E. europaeus does not appear to have spines, which are concealed beneath their fluid filled skin. 24 hours after birth, the fluid is absorbed and the spines are revealed, and, 2 to 3 days later, the young’s musculature is developed enough to allow it to hold the spines erect. These white adolescent spines are replaced by darker spines after about 1.5 days. Pigmented adult spines replace the first two coats after about 2 to 3 weeks, at which time young begin to open their eyes and learn how to roll into a ball. Young are weaned by 4 to 6 weeks old, after which they become independent of parental care, and are able to mate by about 1 year. (Bunnell, 2009; Burton, 1969; Johnston, 1903; Rondinini, 2007; Southern, 1964; de Magalhaes and Costa, 2009)

Weaning usually occurs 6 weeks after birth, at which time young European hedhogs begin venturing out of the nest with their mother. They begin to forage and create an overwintering nest on their own. Most individuals are sexually mature by the first spring after their born. (Bunnell, 2009; Rondinini, 2007)

In the wild, European hedgehogs can live up to six years. In captivity, they can live as many as ten years. (de Magalhaes and Costa, 2009)

Erinaceus europaeus is nocturnal, predominantly solitary, and non-territorial. It meets intentionally with others only during the mating season, but a social hierarchy may exist such that mature females have dominance over prime feeding sites. Hedgehogs have relatively large home ranges that are difficult to defend, and as such, they roam freely during the night. They tend to rest during the day in shallow nests made of twigs, leaves, grass, pine needles, and other foliage. Each nest is utilized by more than one individual, but never at the same time, and hedgehogs may also share urine sites. Aggressive interactions have not been observed between individuals. (Burton, 1969; Forrest, 1899; Jones and Digger, 2009; Rondinini, 2007; Southern, 1964; Walker, 1968)

Erinaceus europaeus travels at an average speed of 110 to 220 yards per hour. They are successful swimmers and climbers and are able to squeeze through tight spaces. When threatened, hedgehogs curl into a ball, exposing their sharp spines while protecting their vulnerable underbelly and face. However, hedgehogs prefer to avoid contact with predators by living in areas devoid of predator odors despite an increase in hedgehog population density. (Burton, 1969; Forrest, 1899; Jones and Digger, 2009; Rondinini, 2007; Southern, 1964; Walker, 1968)

As day length decreases, European hedgehog begin looking for sufficiently insulated hibernation nests. In colder areas, hibernation usually begins in October and lasts until April; in warmer areas, hedgehogs may only hibernate during the coldest of winters. Hedgehogs survive the cold temperatures by storing fat to be used as insulation and as an energy reserve to wake up when necessary. These periodic breaks in hibernation occur every 1 to 2 weeks and last for 1 to 2 days, during which hedgehogs forage for food and urinate. Provided sufficient resources, captive hedgehogs do not hibernate.

European hedgehogs require large foraging areas (often no more than 100 acres) due to inconsistent and unreliable distribution of food. When food is more abundant, such as in home gardens or other agroecosystems, European hedgehogs may have a home range as small as 12 to 25 acres. Males generally have home ranges up to twice the size the female’s home range. (Jones and Digger, 2009; Rondinini, 2007)

European hedgehogs are not particularly noisy, and make mostly grunting, snorting, and hoarse squeaking sounds. Adults are vocal during mating, while feeding, and occasionally when captured. Young may squeak and whistle while in the nest. Due to its nocturnal behavior, European hedgehogs rely heavily on their senses of smell and hearing. In addition to having a well developed sense of smell, they, like many mammals, have a Jacobson's organ in their palate. The organ may have a role in social behavior as both male and female hedgehogs have a variety of scent glands. While the mechanisms of hearing in E. europaeus have not been well studied, research on a related species, the Long-eared hedgehog, has found it capable of processing high-frequency sounds up to 45kHz. (Burton, 1969; Forrest, 1899; Johnston, 1903; Rondinini, 2007; Southern, 1964; Step, 1921)

European hedgehogs are omnivorous, but predominantly feed on insects. They favor beetles, ants, bees, wasps, earwigs, butterflies and moths. Hedgehogs may also eat cockroaches, crickets, grasshoppers, snails, eggs, lizards, snakes, frogs, small rodents, and carrion. (Burton, 1969; Gaglio, et al., 2009; Gordon, 1904; Johnston, 1903; Jones, et al., 2005; Rondinini, 2007; Southern, 1964; Step, 1921)

Predators of the Erinaceus europaeus include dogs, foxes, snakes, large owls, and badgers. To protect themselves, hedgehogs have the ability to curl into a defensive ball that exposes only erected spines. In order to form into a ball, they constriction the panniculus carnosus muscle. When this occurs, the muscles associated with each spine contract, leaving all of the hedgehog’s spines erect. Some predators, such as badgers and foxes, may be able to gain access to the hedgehog by wedging their noses into the crease where the top and bottom of the spiny coat meet. Predators have also been known to drop a balled hedgehog from a height so as to shock or injure the hedgehog long enough for them to take advantage of its exposed underbelly. (Hof and Bright, 2010; Johnston, 1903; Rondinini, 2007; Vermeulen, et al., 2009)

Hedgehogs are omnivorous, feeding on a wide variety of animal (especially insect) and plant material. They may help control insect pest populations in some areas. Hedgehogs are hosts to a variety of parasites including nematodes (Crenosoma striatum, Eucoleus aerophilus, Capillaria erinacei, Capillaria ovoreticulata and Capillaria spp.), trematodes (Brachylaemus erinacei), acanthocephalans (Oliganthorhynchus erinacei), ticks (Ixodes hexagonus), and fleas (Archeopsylla erinacei). (Gaglio, et al., 2009; Hof and Bright, 2010)

Hedgehogs are routinely kept as pets, but the European hedgehog is forbidden as a pet in Europe. Due to their broad diet, hedgehogs may help control insect pests. They have proven useful for the study of numerous diseases including foot and mouth disease, yellow fever, and influenza. Their hair and spines are useful in assessing for environmental pollutants including arsenic, silver, cadmium, lead, cobalt, and Persistant Organic Pollutants (POPs). Traditional remedies have incorporated the blood, entrails, or ashes of European hedgehogs, and some rituals involving hedgehogs have been used to cure baldness and predict the weather. Ancient Romans raised hedgehogs for their meat, and they used parts of the hedgehog, especially their spiny coat, for training work animals. (Burton, 1969; D'Havé, et al., 2005; D'Havé, et al., 2006; Hof and Bright, 2010; Southern, 1964; Vermeulen, et al., 2009)

Hedgehogs are potential vectors for a number of parasites and pathogens including ticks, fleas, mites, ringworm, influenza, yellow fever, Salmonella enteritidis, leptospirosis, and foot and mouth disease. (Burton, 1969; Gaglio, et al., 2009; Southern, 1964)

Formerly a common sight in the UK, local populations of Erinaceus europaeus appear to be rapidly declining. Despite this, E. europaeus is listed as a species of least concern on the IUCN's Red List of Threatened Species. The reasons for its decline are unclear, however, E. europaeus has been included in the UK Biodiversity Action Plan. (Hof and Bright, 2010)