TheEuropean hedgehog (Erinaceus europaeus), also known as theWest European hedgehog orcommon hedgehog, is ahedgehogspecies native to Europe fromIberia andItaly northwards intoScandinavia and westwards intoIreland.[3] It is a generally common and widely distributed species that can survive across a wide range ofhabitat types. It is a well-known species, and a favourite in European gardens, both for its endearing appearance and its preference for eating a range of garden pests. While populations are currently stable across much of its range, it is declining severely inGreat Britain,[2] where it is now Red Listed,[4] meaning that it is considered to be at risk oflocal extinction. Outside its native range the species was introduced toNew Zealand during the late nineteenth and early twentieth centuries.
Skeleton of a European hedgehogSkull of a European hedgehog
The European hedgehog has a generalised body structure with unspecialised limb girdles.[5] It appears brownish with most of its body covered by up to 6000 brown and white spines.[6] The length of head and body is ~160 mm (6 in) at weaning, increasing to 260 mm (10 in) or more in large adults. It has an extremely short tail as an almost vestigial feature, typically 20 to 30 mm (0.8 to 1.2 in).[7] Weight increases from around 120 g (4 oz) at weaning to > 1100 g (40 oz) in adulthood. The maximum recorded weight is 2000 g (70 oz), though few wild specimens exceed 1600 g (55 oz) even in autumn.[5] Adult summer weight is typically somewhat less than in autumn, with an average of around 800 g (28 oz) and adult weights commonly as low as 500 g (18 oz).[8] Males tend to be slightly larger than females, but sex differences in body weight are overshadowed by enormous seasonal variation.[7]
The European hedgehog is unlike any other creature across most of its range. Where it coexists with thenorthern white-breasted hedgehog (Erinaceus roumanicus), the two species are difficult to distinguish in the field, the latter having a white spot on its chest.[2] It is probably the largest hedgehog species and is possibly the heaviest member of the orderErinaceomorpha.[9]
Leucistic or 'blonde' hedgehogs occasionally occur. Such specimens are believed to have a pair of rarerecessivegenes, giving rise to their black eyes and creamy-coloured spines; however they are not strictly speakingalbino. They are extremely rare, except onNorth Ronaldsay and theChannel Island ofAlderney, where around 25% of the population is thought to be blonde.[10] True albinomorphs of the hedgehog occur infrequently.[6]
The European hedgehog is largelynocturnal. It has a hesitant gait, frequently stopping to smell the air. Unlike the smaller, warmer-climate species, the European hedgehog mayhibernate in the winter. However most wake at least once to move their nests.[11]
A European hedgehog eating fish carcass, photographed inAltai KraiA European hedgehog eating fallen fruitsEuropean hedgehog foraging in hedgerow
The European hedgehog is aninsectivore. Its diet consists largely ofearthworms, as well as snails and slugs,beetles, ants, bees and wasps,earwigs, cockroaches,crickets andgrasshoppers, butterflies and moths, andcaterpillars and other insect larvae.[12] Eggs of ground-nesting birds are also taken and carcasses may be foraged on. Hedgehogs may also eatlizards, snakes,frogs and small rodents.[12] Plant matter appears to make up only a negligible part of the hedgehog's diet.[13][14][15]
The breeding season commences after hibernation. Pregnancies peak between May and July, though they have been recorded as late as September. Gestation is 31 to 35 days. The female alone raises the litter, which typically numbers between four and six, though the range is from two to ten. Studies have indicated that litter size may increase in more northern climes. The young are born blind with a covering of small spines. By the time they are 36 hours old the second, outer coat of spines begins to sprout. By 11 days they can roll into a ball. Weaning occurs at around six weeks of age.[16]
A pellet made by owl, with hair and spikes of hedgehog
European hedgehogs may live to more than ten years of age, although the average life expectancy is three years. Starvation is the most common cause of death, usually occurring during hibernation. If alarmed, the animal will roll into a ball to protect itself. Many potentialpredators are repelled by its spines, butpredation does occur. Remains of hedgehogs have been found in the stomachs ofred foxes (Vulpes vulpes),European badgers (Meles meles) andpine martens (Martes martes). A large portion of these may be from hedgehog carcasses, especiallyroadkill. However hedgehogs tend to be absent from areas where badgers are numerous.
Eurasian eagle-owls (Bubo bubo) andgolden eagles (Aquila chrysaetos) are the only regular avian predators of this species and may even prefer them as prey. The owl, after grabbing the hedgehog by its face, tends to skin the mammal's prickly back with its talons before consumption, resulting in several hedgehog backs being found around eagle-owl roosts and nests.[17] In Spain, reduction ofEuropean rabbit (Oryctolagus cuniculus) numbers due torabbit haemorrhagic disease has made the European hedgehog one of the top preferred prey species for eagle-owls.[18] Elsewhere, eagle-owls often prefer these hedgehogs to any other prey species, as the hedgehog can comprise up to 23% by number and 30.7% by biomass of eagle-owl prey remains.[19][20][21] On the Swedish island ofGotland the golden eagle may take larger numbers of hedgehogs than any other prey owing to an otherwise low diversity of native land mammals, although the introduction of European rabbits has shifted the eagle's prey preferences there.[22]
European hedgehogs form nests where they spend much of their time. They construct three types of nest: breeding nests for birth and for protection of litters, day nests, which are used during the summer months, and winter nests orhibernacula, which are used for longer periods during winter months. Nests are often found under structures that can support them, such as roots or branches.[23]
The European hedgehog is native to Europe, with a global distribution extending fromIreland and theIberian Peninsula eastwards through much of western to central Europe, and from southernFennoscandia and the northernBaltic to north-west Russia. It is present also on Mediterranean islands (Corsica,Sardinia,Elba,Sicily), on most of the French Atlantic islands as well as on Irish and British islands (autochthonous and introduced).[24] It is aninvasive exotic species in New Zealand and it has been suggested maybe to have been introduced to Ireland and many of the smaller islands where it occurs.[25]
Colonists took hedgehogs from England and Scotland to New Zealand on sailing ships from the 1860s to the 1890s, mainly as a biological control against agricultural pests or as a pet.[26] Few survived the c. 50–100 days' voyage,[26] but those that did had lost all their fleas. Animals found their first homes in the South Island, where their spread was helped by guards dropping them off at country railway stations. Hedgehogs were introduced to the North Island in the 1890s, but some were also transported from South Island between 1906 and 1911[26] and from then on their numbers increased at an exponential rate. By the 1920s they had become so numerous that game-bird hunters blamed them for reduced bag sizes. Hedgehogs were declared noxious animals and a bounty of one shilling a snout was paid by regional authorities for several years. By the 1950s hedgehogs could be found over the whole country with the exception of the coldest wettest corner of the South Island and alpine areas of permanent snow. Nevertheless hedgehogs have been seen climbing New Zealand glaciers. Hedgehogs do not reach the same weight in New Zealand as in colder parts of Europe. With the milder winters New Zealand hedgehogs hibernate for only three months of the year so do not need to put on so much weight in autumn as their ancestors. In northern New Zealand many hedgehogs do not hibernate at all. One of New Zealand's pioneer hedgehogs probably had faulty teeth for this feature is found in about 50% of today's animals. Most New Zealanders welcome hedgehogs in their gardens since they relish slugs and snails. Conservationists are less happy, since hedgehogs compete for invertebrate food with native bush birds and prey on some rare insects, lizards and ground-nesting birds. As a result extensive hedgehog-control schemes are under way in some parts of the country, killing thousands of them. To judge by roadkill counts, North Island hedgehog numbers were at their highest in the 1950s. Since then, roadkill counts have fallen dramatically from about 50/100 km to less than 1/100 km.[27]
The European hedgehog is found across a wide range ofhabitat types, encompassing both semi-natural vegetation types and those areas that have been heavily modified by man. The range includeswoodland,grasslands such asmeadows andpasture,arable land,orchards andvineyards as well as within the matrix of habitat types found in human settlements. It prefers lowlands and hills up to 600m but is also locally present on mountains, exceptionally up to an altitude of 2000m (e.g.Alps andPyrenees).[28] Outside cultivated land it prefers marginal zones of forests, particularlyecotonal grass and scrub vegetation.[28]
Hedgehogs are most abundant within the gardens, parks and amenity land close to or within human settlements.[29] They are generally scarce in areas ofmarshes andmoorland, probably because of a lack of suitable sites and materials for the construction of winter nests (orhibernacula), which have specific requirements.[6] In Finland they use pine-tree roots especially for nests in the winter.[23]
Hedgehog in autumn in its nest under a bush inBrastad, Sweden
Generally the hedgehog is widely distributed and can be found in good numbers where people are tolerant of their residence in gardens. The IUCN classifies the species as Near Threatened and currently the population as Stable. In some areas they are common victims of road kills and may be hunted by dogs, such as inSardinia.[2] On 28 August 2007, the newBiodiversity Action Plan included the European hedgehog on the list of species and habitats in Britain that need conservation and greater protection.[30][31]
A low coverage assembly of the genome ofErinaceus europaeus was released by theBroad Institute in June 2006 as part of the Mammalian Genome Project.[34]
An estimate of 36.5 million by Burton[35] was based on extrapolating from a density of 2.5 animals/ha (one per acre), but this was based on limited data and is probably an overestimate. A more recent estimate of 1,550,000 in Great Britain[36] (England 1,100,000, Scotland 310,000, Wales 140,000) is more reliable but still has a high degree of uncertainty since it is based on very limited information about hedgehog density estimates for different habitat types.[3] Given this figure, and more firmly established rates of decline,[37] it is now thought likely that there are fewer than a million hedgehogs in Great Britain.[38] In the UK badgers are the main predator of hedgehogs[39] and also compete for some of the same foods.
In 2007 the hedgehog was classified aBiodiversity Action Plan priority species in Britain, largely in response to negative trends identified in national surveys such asMammals on Roads survey,[40] run byPeople's Trust for Endangered Species (PTES), which found an annual decline in counts of road casualties of around 7% from 2001 to 2004.[41][42] Historic data from theNational Gamebag Census suggest a steady decline between 1960 and 1980.[43] Evidence from a questionnaire in 2005 and 2006 also supported an ongoing decline, with almost half of ~20,000 participants in PTES'Hogwatchsurvey[44] reporting the impression that there were fewer hedgehogs than there had been five years earlier.[45]
A review of the available survey data for the population trend of the hedgehog in Britain was undertaken by theBritish Trust for Ornithology (BTO) in a report commissioned by PTES and the British Hedgehog Preservation Society (BHPS).[37] This concluded that, at a conservative estimate, 25% of the British hedgehog population had been lost in a decade.[46] The report also highlighted the importance of long-term monitoring to provide datasets with sufficientpower to allow the changes to the population to be identified. Currently, the most important monitoring programmes involved in collecting information about the status of the British hedgehog population are PTES'Mammals on Roads andLiving with Mammals surveys, and the BTOBreeding Bird Survey andGarden BirdWatch survey.[47] A recent review of these surveys now suggests that rural populations have declined by at least a half and urban populations by up to a third since 2000.[48]
This species has become a seriouspest in areas where it has been introduced outside of its native range. One such location is theWestern Isles of Scotland, where introduced hedgehogs eat the eggs of ground-nesting waders such ascommon snipe,dunlin,common redshank andnorthern lapwing. It is also considered a pestin New Zealand, where it preys upon various native fauna,[49] including insects, snails, lizards and ground-nesting birds, particularly shore birds.[50] As with many introduced animals, it lacks natural predators.
Attempts toeliminate hedgehogs from bird colonies on the Scottish islands ofNorth Uist andBenbecula in theOuter Hebrides were met with international outrage. Eradication began in 2003 with 690 hedgehogs being killed. Animal-welfare groups attempted rescues to save the hedgehogs. By 2007legal injunctions against the killing of hedgehogs were put in place. In 2008 the elimination process was changed from killing the hedgehogs to trapping them and releasing them on the mainland.[51]
From the early 1950s until the 1980s, the hedgehog was sometimes seen as an unofficial symbol ofNATO in numerous countries, as it represented a peaceful animal that bristles in defence.[52]
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^Haigh, A.; O'Riordan, R. M.; Butler, F. (2012). "Nesting behaviour and seasonal body mass changes in a rural Irish population of the Western hedgehog (Erinaceus europaeus)".Acta Theriologica.57 (4):321–331.Bibcode:2012AcTh...57..321H.doi:10.1007/s13364-012-0080-2.S2CID18568953.
^Hubert, P.; Julliard, R.; Biagianti, S.; Poulle, M. L. (2011). "Ecological factors driving the higher hedgehog (Erinaceus europeaus) density in an urban area compared to the adjacent rural area".Landscape and Urban Planning.103 (1):34–43.Bibcode:2011LUrbP.103...34H.doi:10.1016/j.landurbplan.2011.05.010.
^Jones, C.; Moss, K.; Sanders, M. (2005). "Diet of hedgehogs (Erinaceus europaeus) in the upper Waitaki Basin, New Zealand: implications for conservation".New Zealand Journal of Ecology.29 (1):29–35.JSTOR24056190.
^The Encyclopedia of Mammals. Oxford University Press. 2010. p. 431.ISBN978-0-19-956799-7.
^by Konig, Weick & Becking (2009).Owls of the World Yale University Press.ISBN0300142277
^Antonio Martínez, J., & Zuberogoitia, I. (2001).The response of the Eagle Owl (Bubo bubo) to an outbreak of the rabbit haemorrhagic disease. Journal für Ornithologie, 142(2), 204-211.
^Laursen, J. T. (1999).Fødevalg hos Stor Hornugle Bubo bubo i Danmark.Dansk Orn. Foren. Tidsskr 93:141-144.
^Leditznig, C., Leditznig, W., & Gossow, H. (2001).15 Jahre Untersuchungen am Uhu (Bubo bubo) im Mostviertel Niederösterreichs-Stand und Entwicklungstendenzen. Egretta, 44: 45-73.
^Geidel, C. (2012).Entwicklung neuartiger Schutzkonzepte für den Uhu (Bubo bubo)-Abschlussbericht 2012. Gutachten (DBU-Projekt).
^Tjernberg, M. (1981). Diet of the golden eagle Aquila chrysaetos during the breeding season in Sweden.Ecography 4(1):12-19.
^King, C. M.; Carolyn, M.; Barrett, P. (2005).The handbook of New Zealand mammals (Second ed.). South Melbourne, Vic.: Oxford University Press.ISBN0-19-558477-5.OCLC64401930.
^abMitchell-Jones, A.J.; Amori, G.; Bogdanowicz, W.; Krystufek, B.; Reijnders, P.J.H.; Spitzenberger, F.; Stubbe, M.; Thissen, J.B.M.; Vohralik, V.; Zima, J. (1999).The atlas of European mammals. Poyser London. pp.38-39.
^Young, R. P; Davison, J.; Trewby, I. D.; Wilson, G. J.; Delahay, R. J. & Doncaster, C. P. (2006). "Abundance of hedgehogs (Erinaceus europaeus) in relation to the density and distribution of badgers (Meles meles)".Journal of Zoology.269 (3):349–356.Bibcode:2006JZoo..269..349Y.doi:10.1111/j.1469-7998.2006.00078.x.
^Bright, P., George, L. and Balmforth, Z. (2005). Mammals on Roads: development and testing the use of road counts to monitor abundance (draft v. 9). A report to PTES/JNCC.
^Hof, A.R. (2009). A study of the current status of the hedgehog (Erinaceus europaeus) and its decline in Great Britain since 1960. PhD. Royal Holloway, University of London. Egham, Surrey, TW20 0EX, UK.
^Battersby, J. (2005). UK Mammals: Species Status and Population Trends. A report by the Tracking Mammals Partnership No. 1, JNCC/Tracking Mammals Partnership, Peterborough.
^King, Carolyn (1985).Immigrant Killers: Introduced Predators and the Conservation of Birds in New Zealand. Auckland: Oxford University Press.ISBN978-0-19-558115-7.
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