HEDGEHOGS
Hedgehogs are small to medium-sized mammals that are mainly active at night and are well-known for their coat of protective spines. They tend to be solitary, opportunistic omnivores that travel up to two kilometers every night in search of food. Among the places they make their homes are temperate forests, scrublands, grasslands, urban and suburban areas. They often show up in backyard gardens and like to hibernate in parks. [Source: Sydney Collins, Animal Diversity Web (ADW) |=|]
Hedgehog are gentle, somewhat mouselike creatures with white tipped spikes covering most of their body. They are found throughout Europe, Asia and Africa. Their unique design has been so successful the hedgehog has survived for 70 million years, since the age of dinosaurs, virtually unchanged. A few years ago they became popular as pets in the United States. They are popular, pet store owners say, because they don't bite, chew up things, get too big or smell. In the wild, hedgehogs are common in many places, but they have suffered from heavy pesticide use and industrial agriculture. [Source: Chris Reiter and Gina C. Gould, Natural History, July 1998]
Hedgehogs reach a length of about 15 centimeters (six inches) and weigh around half a kilogram (a pound or two). They have poor eyesight but possess acute senses of smell and hearing. Hedgehogs are so named because in England they like to hang around hedges. They are also comfortable in forests, pastures, and backyard gardens. They like to sleep in a burrow or nests of twigs and leaves.
Hedgehogs were a symbol of rebirth for the ancient Egyptians because of the emergence from hibernation and estivation (hote weather hibernation). There are many old stories that characterize hedgehogs in a negative light. in Mongolia, there is a children's folk tale about a greedy and evil hedgehog. In medieval Europe hedgehogs were a sign of bad luck if seen or found in one’s house and it was believed that hedgehogs stole milk from cows and chicken eggs in the night. Shakespeare used the word "hedgehog" as an insult and many medieval Europeans thought that witches could transform themselves into hedgehogs. In response to this, the English Parliament gave a bounty for all hedgehogs, dead or alive. [Source: Sydney Collins, Animal Diversity Web (ADW) |=|]
Book: “The Hedgehog’s Dilemma: A Tale of Obsession, Nostalgia, and the World’s Most Charming Mammal” by Hugh Warwick, 2008]
See Separate Article: HEDGEHOG SPECIES factsanddetails.com
Erinaceidae (Gymnures and Hedgehogs)
Gymnures, also called hairy hedgehogs or moonrats, are mammals belonging to the subfamily Galericinae, in the family Erinaceidae. They resemble rats but are not closely related as they are not rodents; they are instead closely related to hedgehogs, which also belong to Erinaceidae. They are thought to have appeared in Eastern Asia before their closest relatives, and changed little from the original ancestor, which is thought to have been also the ancestor of the shrews.
The family Erinaceids — hedgehogs and gymnures — are perhaps the most similar of all extant mammals to the very earliest mammals. According to Animal Diversity Web: Erinaceid fossils, however, date back only to the Eocene Period (56 million to 33.9 million years ago), while their extinct ancestors, the Adapisoricidae, are known from the Cretaceous (145 million to 66 million years ago). The family is made up of 17 species grouped in seven genera, and can be found in Africa, Eurasia, southeastern Asia and Borneo. Hedgehogs and gymnures range in size from that of a mouse to a small rabbit. [Source: Deborah Ciszek and Phil Myers, Animal Diversity Web (ADW) |=|]
Erinaceids are closely related to shrews. They can be identified by their dental formula (2-3/3, 1/1, 3-4/2-4, 3/3 = 36-44), complete zygomatic arches (the jugal is present), eyes and ears of moderate size, and plantigrade foot posture (for walking on the soles of the feet, like a human or a bear). The anterior incisors in some species are enlarged, but not to the degree seen in their smaller cousins, the shrews. The upper molars are quadritubercular and appear bunodont; the lowers include well developed trigonids and talonid basins. |=|
Hedgehogs (but not gymnures) are covered with sharp spines. Many species of hedgehogs can roll up into a ball, hiding all vulnerable areas of the body under the protective spines. Gymnures lack spines but when threatened, produce a foul smell. Erinaceids live under logs or in burrows that they dig. They eat a wide variety of foods, including invertebrates, reptiles, (hedgehogs are curiously resistant to snake venom and other environmental toxins), carrion, roots, and fruits. Hedgehogs are active only at night, and some species hibernate in the winter. They appear to be facultatively heterothermic (having a body temperature that fluctuates with the surrounding environment),. Gymnures may be active during the day. Even though they are mainly terrestrial, erinaceids tend to be good climbers and swimmers. Most have one or two breeding seasons per year. In most species this is the only time adults associate, at other times they are solitary. The young are born with soft spines that quickly harden. |=|
Hedgehog History and Taxonomy
The oldest known ancestors of hedgehogs were in genus Litolestes and genus Leipsanolestes, which lived during the Paleocene Period (66 million to 56 million years ago). Their fossils have been discovered in Canada, Montana, and Wyoming. These prehistoric animals were similar in size to modern hedgehogs and were also insectivores. [Source: Sydney Collins, Animal Diversity Web (ADW) |=|]
In prehistoric times, these were some pretty strange hedgehogs. Nine million years ago a giant carnivorous hedgehog ruled an island in the Mediterranean. Thirty million year ago a hedgehog became so adapted at digging burrows jackhammer-style with its head it may have evolved out its legs to become the first limbless mammal.
Because of their spines, many people believe hedgehogs are closely related to porcupines but that is not the case. There are much more closely related to moonrats and gymnures (family Galericinae), moles and desmans (family Talpidae) and shrews (family Soricidae). In the past, hedgehogs were called urchins due to their spiked appearance, hedgepigs and furze-pigs.
Convergent Evolution of Hedgehogs, Porcupines and Echidnas
Marion Rae of Reuters wrote: Once upon a time, millions of years ago, the humble hedgehog spread over Africa, Asia and Europe, while a freak of nature gave Australia the spiky echidna. Australia is home to the dianthus erinaceus or hedgehog plant, the chocolate hedgehog cake and the common hedgehog slug, and US porn star Ron "Hedgehog" Jeremy calls Australia home, but the lovable hedgehog is nowhere to be found on the vast continent which was cast adrift at least 200 million years ago. Curiously, the hedgehog made famous by writer Beatrix Potter and Australia's echidna often fall victim to mistaken identity, along with the spiny porcupine familiar to North Americans. [Source: Marion Rae, Reuters. August 13, 2003]
Yet they are, in fact, one of the world's clearest examples of convergent evolution, say scientists. Convergent evolution, the emergence of chance look-alikes, involves an evolutionary pattern in which completely unrelated species share similar traits because each has independently adapted to similar ecological and environmental conditions. "If you were a little animal and you eat insects you have to be on the ground, then one of your main problems in life is that you get eaten by big things, so you have to come up with a defense mechanism," said Erna Walraven, senior curator at Sydney's harborside Taronga Zoo. "Both hedgehogs and echidnas, independently, have come up with spikes," Walraven said.
The hedgehog is essentially an insect-eating mammal and the porcupine is a large plant-eating rodent, while the echidna is part of an elite group of monotremes — along with the Australian platypus — which are a mixture of mammal and reptile. "If you go back 200 million years ago, you have a number of different animal mammal groups evolving in different spots and in different ways," said Anne Musser, convergent evolution specialist at the Australian Museum.
About 350 million years ago, Antarctica, India, Australia, Africa and South America formed a single landmass, a southerly "supercontinent" named Gondawana by scientists. Australia, Antarctica and South America were all joined as East Gondawana before Australia separated and moved north as the landmass broke up, while Antarctica moved south and froze over. "As Gondawana separated the animals that were marooned were the ones that were able to evolve into what we have now — marsupials made it south in time to get aboard the ark that was Australia," Musser said. The hedgehog became part of northern hemisphere history and the American porcupine flourished in its own ark.
While people often refer to Australia's echidna as a cousin of the hedgehog, Taronga Zoo's Walraven said hedgehogs and echidnas were as far removed from each other as they could be. The reproductive system is what typifies the difference. The echidna, a monotreme, has a pouch, lays eggs and then suckles its young. The hedgehog gives birth to "hoglets", usually four to six offspring at a time. Their tiny spines are covered with a membrane which shrivels away and hardens within hours. The young echidna hatches after about 10 days incubation and will then remain in its mother's pouch for seven to eight weeks. During this time it gradually becomes spiky. There are many species of hedgehogs, given their almost global distribution, but the one most commonly referred to — and fictionalized by children's writer Beatrix Potter with her Mrs. Tiggy-Winkle hedgehog character — is the erinaceus europaeus. Hedgehogs are usually brown and yellow and have an immensely developed stomach muscle which allows them to curl up into a ball for protection when they are frightened. It eats bugs and berries and has a penchant for slugs, bird eggs and snakes.
Australia's echidna is about 40-55 centimeters long, the erinaceus europaeus hedgehog is 20-25 centimeters long with a round body, stiff spines and a hairy underbelly. The echidna, one of the oldest unchanged creatures in the world, likes to live in the bush and comes out at night to eat ants and termites with its sticky tongue. There are more than a dozen species of hedgehog found throughout Africa, Asia and Europe, including the British Isles, where they feast on the eggs of now endangered birds. The American porcupine, about 75 centimeters long when fully grown, has quills protecting its back, sides and tail, which usually lie flat against its body until the animal is faced with danger.
RELATED ARTICLES:
PORCUPINES IN ASIA factsanddetails.com
ECHIDNAS: CHARACTERISTICS, BEHAVIOR AND REPRODUCTION ioa.factsanddetails.com
SHORT-BEAKED ECHIDNAS: CHARACTERISTICS, BEHAVIOR AND REPRODUCTION ioa.factsanddetails.com
LONG-BEAKED ECHIDNAS: SPECIES, CHARACTERISTICS, BEHAVIOR AND REPRODUCTION ioa.factsanddetails.com
Hedgehog Behavior
Hedgehogs are generally solitary, except during the mating season, terricolous (live on the ground), nocturnal (active at night), motile (move around as opposed to being stationary), sedentary (remain in the same area), engage in hibernation (the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal’s energy requirements) and sometimes estivate (sleep in for period in the summer). [Source: Sydney Collins, Animal Diversity Web (ADW) |=|]
Many hedgehogs travel around one or two kilometers per night within their home ranges to forage for food, They often stay within the same home range throughout their life if resources are consistently available. This means that they require a relatively large home range. Although hedgehogs are not overtly territorial they may become aggressive if they encounter another hedgehog, huffing through their nose, squealing, lowering their head, and raising their spines in warning.
According to the Nature Lover's Library: Field Guide to the Animals of Britain: "If a hedgehog is seen to froth at the mouth and twist itself about, it is not sick but is spreading the frothy saliva on its fur and spines with its tongue. The purpose of the behavior is unknown, but it is quite normal." This behavior is called self-anointing or anting and is usually done when encountering a strange scent. Some scientists believe anointing is a way for hedgehogs to camouflage themselves scent-wise in the case that the new scent proves to be dangerous. Others believe that anointing is another form of defense, in which predators have the potential to get poisoned or deterred by the froth if they come into contact with the hedgehog's spines. |=|
Hedgehogs spend about 80 percent of their awak time time foraging for food and nest materials. They are most active during the middle hours of the night, returning to their nests for a period of time, then resume foraging until dawn. Males are known to move faster and cover more ground in their relatively larger home ranges than females, especially during the mating season. In the late summer, females tend to become more active and enlarge their home ranges after their young have been weaned. |=|
According to Animal Diversity Web: hedgehogs build multiple types of nests. One type is a short-term day nest, of which the woodland hedgehogs use to rest and reside during the daytime outside of the hibernation period. They typically only use day nests for a few days at a time before moving onto a new one. Nests are built within thorny or dense vegetation, bramble, and nettles. Another type of nest is a breeding or reproductive nest. As the name suggests, breeding/reproductive nests are constructed for the purpose of protecting and raising hoglets until they are old enough to live on their own. The third type of nest is the hibernation nest, also known as a hibernaculum. Woodland hedgehogs construct many places to hibernate because they tend to move up to four times between such nests during hibernation and they can stay in these nests for up to six months as they hibernate. Males tend to enter and emerge from hibernation earlier than females to expand their home ranges and prepare for the successive breeding season.
Hedgehog Diet and Feeding Behavior
Hedgehogs are omnivorous (eat a variety of things, including plants and animals) but feed primarily on insects, spiders, frogs, seeds and other kinds of vegetation. Sometimes the feed on mice, and even snakes. Hedgehogs often rely on their sense of hearing to detect the sounds of prey, such as rustling leaves and scratching and digging insects.
European hedgehogs predominantly feed on insects. They favor beetles, ants, bees, wasps, earwigs, butterflies and moths. They may also eat cockroaches, crickets, grasshoppers, snails, eggs, lizards, snakes, frogs, small rodents, non-insect arthropods such as spiders, terrestrial worms. and carrion. Among the plant foods they eat are seeds, grains, nuts and fruit. |=|
Woodland hedgehogs, which include European hedgehogs, require about 90-150 kcal worth of food per day. Their slow metabolisms not only make them temperature-sensitive, but also sensitive to food availability. Up to 160 grams of beetles, caterpillars, earthworms, slugs, millipedes, and earwigs are consumed per day. When supplies of these prey are scarce they have been reported to preying on the eggs of ground-nesting bird species, carrion, fungi, and small, reptiles, or amphibians. Older individuals tend to specialize on one prey type at a time, and they often exhibit prey switching on a seasonal basis. Before entering engage in hibernation woodland hedgehogs often need to attain a body weight of at least 450 grams and lose as much 20 percent of this weight during hibernation. [Source: Sydney Collins, Animal Diversity Web (ADW) |=|]
Hedgehogs that live in or close to human-inhabited areas tend to have better access to food than those who don't. Especially in Britain, mny people leave out water and food bowls of meat-based pet food or mealworms for wild hedgehogs. Woodland hedgehogs also take advantage of farm crops, garden fruits and vegetables, and the invertebrates they find in such areas, like snails and slugs. Woodland hedgehogs are even known to rummage through trash in backyards or parks.
Hedgehog Predators and Defenses
Predators of the European hedgehogs include dogs, foxes, snakes, large owls, and badgers. To protect themselves, hedgehogs curl themselves into a defensive ball that exposes only erected spines. These grapefruit-size balls are difficult for humans to pick up or predators to bite. 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. [Source: Colin Roberts, Animal Diversity Web (ADW) |=|]
While adult hedgehogs are well protected from predators by to their spines, juveniles are more vulnerable and are often sought out by predators such as large owls, badgers and foxes, and, in human-settled areas, domestic dogs. Although woodland hedgehogs do not directly attack attackers they do "lunge" or "jump" at threats while in a ball in order to gain distance. They also make vocalizations such as huffing, snorting, and hissing. Their earth-toned coloration serves as camouflage. [Source: Sydney Collins, Animal Diversity Web (ADW) |=|]
Hedgehogs have a resistance to but are not immune to snake and scorpion venom. Woodland hedgehogs can eat venomous snakes without consequence.The ancient Egyptians used to wear hedgehog amulets to ward off snakebites. The way they fight snakes is roll up in a ball and use their spines to fend off the snake strikes, When the snake wears itself out or is injured by spines, the hedgehog emerges from the ball and goes in for the kill. Scientists believe woodland hedgehogs have a neutralizing agent (a protein named erinacin) that combats venom's effects in the blood. |=|
Hedgehog Spines
The 5,000 to 7,000 spines on the hedgehog's back and sides are actually modified hairs with hair chambers that became stiff when the animal is frightened or angry. To form into a ball requires constriction of the panniculus carnosus muscle. When this occurs, the muscles associated with each spine contract, leaving all of the hedgehog’s spines erect. Unlike porcupine quills, hedgehog spines are short, lightweight and flexible. When a hedgehog feels threatened special muscles cause it to ball up and cinch its head and legs within a fleshy hood.
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. |=|
When relaxed, the spines lay flat against the body. When threatened, hedgehogs exhibit piloerection and their spines jut out in all directions. Hedgehog spines are also very efficient at wicking moisture and absorbing shock from falls or impacts, minimizing injury. When born, hoglets are furless and only have about a hundred spines that are contained within a fluid membrane to protect the mother during birth, but these preliminary spines harden and grow alongside the thousands of adult spines they eventually obtain. Spines are gradually dropped and replaced throughout the hedgehogs' lifetimes in a process known as quilling, [Source: Sydney Collins, Animal Diversity Web (ADW) |=|]
Hedgehog Senses and Communication
Hedgehogs sense using vision, touch, sound and chemicals usually detected with smell and communicate with touch, sound and chemicals usually detected by smelling. They also employ pheromones (chemicals released into air or water that are detected by and responded to by other animals of the same species) and scent marks produced by special glands and placed so others can smell and taste them.
The black eyes of hedgehogs offer rather poor eyesight, but their small, rounded ears and protruding black noses provide excellent hearing and an exceptional sense of smell. Smell is very important locating prey and is believed to be the most common means of communication as overlapping home ranges are common. It has been theorized that such communication though is more of a way to avoid each other than exchange information as hedgehogs are mostly non-territorial and solitary. As a nocturnal hunters and prey animals, good hearing and smelling are useful for tracking and avoiding predators and locating insects, carrion and small reptiles.[Source: Sydney Collins, Animal Diversity Web (ADW) |=|]
Hedgehogs are not very vocal but they can be if necessary. When in major distress, they may emit a high-pitched squeal as they roll into a protective ball. When giving warning to a potential predator or another hedgehog, they huff and grunt in their defensive ball position, sometimes slightly lunging toward the threat to gain distance or weaponize their raised spines.
European hedgehogs make mostly grunting, snorting, and hoarse squeaking sounds. Colin Roberts wrote in Animal Diversity Web: Adults are vocal during mating, while feeding, and occasionally when captured. Young may squeak and whistle while in the nest. Due to its nocturnal (active at night), 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 European hedgehogs 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. [Source:Colin Roberts, Animal Diversity Web (ADW) |=|]
Hedgehog Mating and Reproduction
Hedgehogs are polygynandrous (promiscuous), with both males and females having multiple partners. After ejaculating sperm male hedgehog produce a kind of plug which seals the female's orifice and prevent competitors from impregnating the female. Among woodland hedgehogs the breeding season occurs sometime between April and September depending on the region. Sexual maturity for males and females is reached by nine to eleven months of age on average. [Source: Sydney Collins, Animal Diversity Web (ADW) |=|]
Hedgehogs are mostly solitary and often only interact when mating. Females can mate with more than five males in one breeding season while males try to mate with as many females as possible before entering hibernation. Males emerge three to four weeks earlier from hibernation than females to expand their home ranges and travel wider distances to find mates. Aggression between males during the breeding season has been observed, but because hedgehogs are generally not territorial and do not defend their mates, such fights are rare and when they do occur and over quickly.
Females have multiple successive estrus cycles (go into "heat") during the breeding season. When a male finds a potential mate, the female hisses, grunts, and "pops" (raises) her spines in defense as the male circles her. If the female is receptive to the male, she relaxes her spines and crouches closer to the ground, allowing the male to mount her and copulation occurs. If the female is not receptive, she does not allow the male to come near her and the male eventually leaves to find a more receptive mate. After mating, the female and male go their separate ways, likely to search out other mates. |=|
Hedgehog Offspring and Parenting
Hedgehog young are altricial, meaning they are relatively underdeveloped at birth. Parental care is provided by females. Males do not involved in the raising of offspring and separate from their mates after mating. As females may mate with several males it is not clear who the father is. There is an extended period of juvenile learning. [Source: Sydney Collins, Animal Diversity Web (ADW) |=|]
Sydney Collins wrote in Animal Diversity Web: After gaining enough weight (700 grams or more) to ensure a healthy birthing process, females construct a breeding or reproductive nest that they will share with their offspring. Females can have up to two litters per breeding season with an average of 4-5 hoglets per litter, although it is rare for mothers to successfully raise more than three offspring to independence. Hoglets are born blind with a weight range of 8 to 25 grams. Their eyes and ears open after 12-15 days, and after their deciduous teeth are lost around four months, their permanent teeth emerge around 7-9 weeks of age. The weaning period is about 5-6 weeks. At 3-5 weeks old, hoglets accompany their mother outside the breeding/reproductive nest to help forage before becoming completely independent around 4-6 weeks old, weighing 250 grams or more. Once independent, juveniles permanently leave the nest and venture alone. |=|
Spontaneous infanticide or desertion has been observed by woodland hedgehog mothers if the breeding nest is disturbed when the hoglets are newly birthed. Disturbances include predator activity or other threats. The reason for this behavior is unknown, especially since mothers often choose to relocate the breeding nests rather than commit infanticide or desertion if the hoglets are older. |=|
Soon after their eyes open, hoglets started gaining their adult spines and teeth to accompany their mother on foraging expeditions outside the nest. During this time, hoglets learn vital foraging behaviors from their mother. Hoglets are are usually independent soon after they are fully weaned. Once independent juveniles leave the nest, they do not return nor have any notable association with their mother.
Hedgehogs and Humans
Hedgehogs have appeared in Egyptian myths, Greek fables, Chinese poems, Latvian folktales and Monty Python skits. In "Alice in Wonderball" hedgehogs were rolled up like balls and struck with flamingos in the Queen's game of Castle Croquet. In his book about hedgehogs, Hugh Warwick wrote in that Yes, they are cute but something beyond cuteness inspires passion, even obsession in hedgehog devotees. No other animal, Warwick writes, allows us to get so close. Hedgehogs in love, Warwick says, can’t get close to each other without hurting each other, so they back away. [Source: Susan Salter Reynolds, Los Angeles Times, November 23, 2008]
The 9th-century Chinese poet Chu Chen Pu wrote:
He ambles along like a walking pincushion,
Stops and curls like a chestnut burr.
He's not worried because he's so little.
Nobody is going to slap him around. “
Britain in particular has a deep affection for hedgehogs. They are a symbol of the National Land Trust. During particularly hot summers, television news reports advise people to leave water our for hedgehogs. Many people build wood or cardboard houses for hedgehogs to nest in. Some make protective corridors for the hedgehogs to safely pass through when traveling between gardens, across roads, and through fencing. In the late 1990s, there were 40 hedgehog hospitals in Britain. Lincolnshire had one of the first. Over 500 of the creatures are brought into the hospital each year, many of them victims of road accidents. The survival rate of the hospital is surprisingly good: 70 percent. To raise funds for their charitable work the hospital sells T-shirts and even has hedgehog boot wipers.
A hedgehog was the featured animal in Beatrice Potter's "The Tale of Mrs. Tiggy-Winkle." "And what are you dipping into the basin of starch?"...There' little dicky shirt-front belonging to Tom Titmouse—most terrible particular!” said Mrs. Tiggy-Winkle. In 1996, Perky Petfood began marketing special canned food for hedgehogs called Spike's Dinner. A spokesman for Perky Pefoods said, "We fed it to fat ones, thin ones and fussy ones, and there's been only hedgehog that hasn't eaten it." A portion of the profits from the wild petfood go to the St. Tiggywinkles hedgehog hospital.
Image Sources: Wikimedia Commons
Text Sources: Animal Diversity Web animaldiversity.org ; National Geographic, Live Science, Natural History magazine, David Attenborough books, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Discover magazine, The New Yorker, Time, BBC, CNN, Reuters, Associated Press, AFP, Lonely Planet Guides, Wikipedia, The Guardian, Top Secret Animal Attack Files website and various books and other publications.
Last updated June 2025