Hedgehogs are small, stout mammals characterized by sharp, keratinized spines or quills on their bodies. They are named so because they creep through hedges, grunting like pigs in search of insects, worms, beetles, termites, and other potential prey.
Sometimes mistaken for porcupines or echidnas, these animals are placed under the subfamily Erinaceinae (under the family Erinaceidae) and are most closely related to moonrats, shrews, and moles.
They are native to Europe, Asia, and Africa. Mostly nocturnal, they spend most of the day sleeping under rocks and bushes. Currently, 17 confirmed species of hedgehogs are classified under five genera.
Depending on the species, hedgehogs are around 4 to 12 in (10 to 30 cm) long.
Hedgehogs are small mammals with short, powerful limbs and large feet equipped with claws. They usually have five toes on each foot, except for the four-toed hedgehog, which, as its name suggests, has four toes per foot. Their bodies are typically brown or black, though some found on the Channel Islands are blonde. Hedgehogs also have a tiny tail, about 2 cm long, usually hidden beneath their dense coat.
These animals are easily recognized by spines made of keratin (almost 6,000 in number) called quills covering the body, except for the belly, face, and neck, which have coarse hair. Often, these quills are banded and fade towards their tips. Although these spines resemble those of porcupines, unlike them, they do not detach from the body easily and are not poisonous.
They have a long pig-like snout that facilitates olfaction and large ears with good auditory sensitivity.
The name ‘hedgehog’ was derived in 1450 from the Middle English terms hegge, which refers to the hedge where these animals frequent, and hogge, for their pig-like snout. 17 confirmed species of hedgehogs are classified under 5 genera: Atelerix, Erinaceus, Hemiechinus, Mesechinus, and Paraechinus.
These mammals are native to Europe, Asia, and Africa and have been introduced by humans to New Zealand, where they are now a thriving invasive species. In Europe, they range from the Mediterranean to Scandinavia. No species are currently found in Australia and the Americas, though an extinct genus, Amphechinus, once thrived in North America.
Hedgehogs inhabit various habitats, ranging from deserts and meadows to forests and savannas. They prefer staying on the ground and usually do not live in trees. In Africa, they are even found roaming around in city streets.
Hedgehogs are omnivores with a diverse diet that includes insects, small invertebrates, and plant materials such as roots, seeds, berries, and melons. The European hedgehog primarily feeds on earthworms, beetles, millipedes, caterpillars, earwigs, snails, slugs, and occasionally bird eggs and chicks.
In contrast, hedgehogs residing in African deserts have a more varied diet adapted to their environment, consuming rodents, snakes, scorpions, and even carrion from dead animals. The Southern African hedgehog’s diet is especially broad, including frogs, lizards, termites, moths, and fungi, like mushrooms.
Interestingly, they can consume up to one-third of their body weight in just one night.
These mammals are primarily nocturnal, foraging at night and resting during the day beneath rocks, bushes, or in dens they dig underground. They display distinct behaviors depending on the circumstances, including rolling into a ball for protection, a self-anointing behavior where they spread frothy saliva over their spines, and a range of vocalizations to communicate.
When a hedgehog senses danger, it raises its quills in a crisscross pattern. Using its muscles, it curls its head, limbs, and tail, forming a solid, spiky ball that is almost impossible for its predators to open.
When a hedgehog encounters an unfamiliar scent, it begins to chew the object that carries the smell. This creates a foamy froth as the hedgehog mixes the scent with its saliva, which it then spreads over its body using its tongue. This behavior, called ‘anointing,’ is assumed to help the animal blend in with the local environment’s scent and may even deter predators by transferring the scent, along with other potential irritants, to the attacker through its spines.
They are quite vocal, emitting various sounds, such as grunts, squeals, and snuffles. While adults generally grunt and squeal when excited or frightened, young hedgehogs, when lost, produce a twittering or whistling sound to address their mother.
Relative to their size, hedgehogs have quite a long lifespan. In the wild, larger species survive for about 4 to 7 years, while smaller species live for 2 to 4 years. In contrast, when under captivity, they live up to 10 years.
Hedgehogs gather only during the breeding season and form pairs prior to mating. Males often engage in courtship by circling a female in heat, sometimes for hours at a stretch. Once they have mated, the pair breaks, and the hedgehogs part ways.
After a gestation period of 35 to 58 days, the young (known as hoglets or piglets) are born once or twice a year. For large species, the litter comprises 3 to 4 individuals on average, while smaller species give birth to 5 to 6 individuals. The hoglets are born blind and resemble white caterpillars in appearance.
The newborns possess soft and flexible quills encased in puffy, fluid-filled skin to prevent injury to the mother. In a day, this skin slowly shrinks and sheds and is replaced by adult spines, following which about 150 new quills emerge, a process known as quilling).
When the hoglets are about a week old, they compete and push each other for access to milk. Around this time, the young are extremely vulnerable to predation, and the mother protects them actively, especially from other male hedgehogs, which often prey on the hoglets. In about a month, they acquire dense, dark quills on their backs with their eyes open. Eventually, they are weaned in about 6 to 13 weeks.
They are primarily preyed upon by birds, such as owls, ferrets, and other carnivorous mammals. Some species, like long-eared hedgehogs, fall prey to wolves, foxes, and mongooses. In Europe, the European badger is the primary predator.
Humans also kill these animals for food and medicinal value.
Most hedgehog species have stable populations and are classified as Least Concern (LC) on the IUCN Red List. However, some species face greater risks: the Western European hedgehog is categorized as Near Threatened (NT), while the long-eared hedgehog is listed as Vulnerable (VU) in Europe. The primary causes of the decline in hedgehog populations include habitat loss through encroachment, particularly due to increased agricultural activities and road construction.
In China, Hugh’s hedgehog populations are dwindling due to their use in food and traditional medicine. Similarly, the Daurian hedgehog is experiencing a sharp decline across China, Mongolia, and Russia due to the spread of mining activities and overgrazing. The Indian hedgehog faces a similar threat in India and Pakistan, where agricultural land continues to encroach upon their natural habitats.
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