Living Organisms / Animalia / Craniata / Mammalia / Insectivora / Erinaceidae / Erinaceus / Species:

< >  LIFE STAGES with literature reports for the West European Hedgehog: Use sub-contents list below, or simply scroll down the page to view findings.

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LIFE STAGES - Editorial Comment

Editorial Comment (Editorial Overview Text Replicated on Overall Species page - Erinaceus europaeus - West European Hedgehog)

BREEDING SEASON: Hedgehogs are seasonal breeders with male sexual behaviour from March or April until August or September. In the UK nestlings may be found as early as April and as late as October. At higher latitudes the breeding season starts later and ends earlier while in New Zealand the main breeding season is November to March: a reverse of the northern hemisphere season.

OESTRUS/OVULATION: Hedgehogs are seasonally polyoestrous. Data from one study indicate that many matings do not result in conception but a period of pseudopregnancy prior to the next oestrus; several cycles of oestrus and pseudopregnancy may occur before conception. Following gestation and birth there may be a period of lactational anoestrus although a post-partum oestrus has sometimes been described. Early loss of a litter is likely to result in rapid return to oestrus and fertile mating. In autumn females enter a period of seasonal anoestrus.

GESTATION/PREGNANCY: Gestation has been calculated to last about 35 +/- 4 days; occasional records indicate the possibility of pregnancies lasting more than 40 days; this may be related to adverse environmental conditions triggering a period of torpor during (early) pregnancy. Hedgehog embryos are evenly distributed between the two horns of the uterus and post-implantation losses appear to be low.

PARTURITION/BIRTH: Births may occur in Britain from May (rarely April) to September or even October. Sows construct a breeding nest or burrow within which they give birth. There have been few observations of parturition; disturbance around the time of birth carries a high risk of maternal cannibalism. Hoglets may be born in anterior (head first) or posterior (tail first) presentation. The fetal membranes and placenta from each neonate are eaten by the mother who moves her offspring carefully with her mouth and positions them by or under her belly.

NEONATAL/DEVELOPMENT:

  • At birth hoglets are hairless, pink, with sealed eyes and ears and no spines, about 70 mm (+/- 15mm) long and 8-25 g in weight.
  • The first white spines appear within the first day of birth. The second, pigmented, set of spines begin to emerge at 36-48 hours after birth and are the main spines by two to three weeks; these are replaced by the first adult spines from about six weeks old. 
  • Hoglets are able to roll up partially by 11 days and fully by about 28 days. 
  • The eyes and ears open at about two weeks old; fur is growing on the body by about this time. Thermoregulation is poor before two weeks old but is fully developed by about 27-32 days.
  • Teeth start to erupt by about 20-21 days. They first take solid food at about 21-23 days and are fully weaned by 38-44 days old.
  •  Body weight may double in the first week, reaching six times birth weight by three weeks and 200-235 g by six weeks.

LITTER SIZE: Litter size in Britain averages four to five at birth. The range of litter size recorded is two to 10. About 20% of hoglets may die prior to leaving the nest.

TIME BETWEEN LITTERS / LITTERS PER YEAR: In central and southern Europe, where the breeding season is longer, and in New Zealand, females may raise two litters in a single breeding season. In Britain it is probably rare that a female conceives, lactates and weans one litter then successfully repeats the process; one such instance has been recorded in captive hedgehogs (litters born May and August and weaned at 43-45 and 42 days respectively). Late litters in females showing evidence of prior lactation in the same season are probably more commonly due to early loss of the first litter. In geographical areas with a shorter breeding season, such as Sweden, only one litter is possible per year.

LACTATION / MILK PRODUCTION: Lactation lasts about four to six weeks. Immunoglobulin absorption in the gut of the hoglets continues for at least 20 days and possibly 30 days or longer. Hedgehog milk is highly concentrated, rich in protein and fat and low in lactose.

SEXUAL MATURITY: Sexual maturity may occur at about nine to 12 months old in the wild, i.e. in the year following birth, and possibly as young as six months in captivity. Pregnancy has been recorded rarely in females weighing as little as 400 g but more usually 550-600 g or higher.

MALE SEASONAL VARIATION: The reproductive tracts of male hedgehogs show considerable seasonal changes.

LONGEVITY / MORTALITY: In the wild hedgehogs which reach five years old are considered to be "old" and maximum lifespan is probably six to eight years. In captivity 10 years may be reached and as high as 14 years has been reported. Average life expectancy in individuals which survive to weaning is probably two years. (Details of Age Estimation Techniques are available in the Detailed Literature Reports.)

(References are available in detailed literature reports below)

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Breeding Season

Source Information SUMMARY: Hedgehogs are seasonal breeders with male sexual behaviour from March or April until August or September. In the UK nestlings may be found as early as April and as late as October. At higher latitudes the breeding season starts later and ends earlier while in New Zealand the main breeding season is November to March: a reverse of the northern hemisphere season.
  • Hedgehog sows are seasonal breeders. Sexual activity typically begins shortly after emergence from hibernation but varies with region.(B228.8.w8)
  • In the majority of the European species' range, male testicular activity begins during hibernation from January with full spermatogenesis and male sexual behaviour by March or April. Activity in the testes typically persists until August and therefore late litters are not uncommon. (B228.8.w8, B260.6.w6, B289.3.w3) Regression of the testes in autumn is rapid, with complete quiescence by the beginning of October. (B289.3.w3)
  • Studies of male hedgehog sexual activity in Fennoscandia (Finnish-Russian-Norwegian border) and Finland show that the peak of the rut occurs in late May/ early June and sexual activity by the boar rapidly declines after this time. As a consequence later autumn hedgehog litters are exceptional in these range states.(B228.8.w8)
  • Early resumption of reproductive system activity occurs prior to the end of hibernation in sows as with boars, with elaboration of the uterine lining and ovarian follicular activity.(B228.8.w8)
  • In the UK, hedgehog courtship behaviour or gestation occurs between March and October.(B228.8.w8) Peak courtship behaviour has been recorded in the month of August.(B228.8.w8)
  • Outlier observations in the UK include courtship behaviour at the end of September, nestlings born as early as April and as late as October.(B228.8.w8)
    • In one survey the latest birth, from a female collected in Nottinghamshire, occurred on 13th October. (J46.136.w1)
  • A survey to investigate the proportion of sows pregnant throughout the season identified an average pregnancy rate of 44% (n=63) in May-July and 52% (n=25) in September.(B228.8.w8)
  • Collections of females from May to September in Caernarvonshire and Nottinghamshire found 11/21 females to be pregnant in May, 6/15 in June, 11/27 in July, 1/4 in August and 13/25 in September. (J46.136.w1)
  • Mild climate in New Zealand permits breeding throughout a large proportion of the year, however, the main breeding season occurs in November to March, which corresponds to an approximate reversal to the situation in Europe as would be predicted.(B228.8.w8)
  • In the Mackenzie Basin, New Zealand, pregnant females were recorded early November to January. (J190.31.w1)
  • Courtship behaviour can begin as early as April in years where ambient temperature is particularly warm but tends to occur from May onwards.(B262.10.w10)
  • The breeding season of the hedgehog extends between April and September with peak courtship activity between May and June.(B254.14.w14, B261)
  •  The hedgehog breeding season extends from April to August. (B258.w7)
  • Studies of the reproductive tract have shown that for British hedgehogs females are anoestrous from the beginning of October to the end of March, with ovulation before the middle of April considered "probably uncommon" and pregnancies occurring May to September. (J68.223.w1)
  • Studies of the reproductive tract have shown that for British male hedgehogs the testes are fully active from April to the end of August with a rapid retrogression thereafter such that they are comparatively quiescent (still with some production of spermatogonia and spermatocytes, but no production of mature spermatozoa) by the beginning of October and until the end of the year, then begin to develop once more in January with the most rapid growth at the end of March. There is enormous hypertrophy of the accessory sexual organs in the breeding season. (J68.223.w2)
  • Reproductive activity varies with latitude: testosterone levels were found to rise a month later at 57N than at 46N and to fall a month earlier; spermatogenesis also occurs for a shorter period at the higher latitude. (J206.84.w1)

(B228.8.w8, B254.14.w14, B258.w7, B260.6.w6, B261, B262.10.w10, B289.3.w3, J46.136.w1, J68.223.w1, J68.223.w2)

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Oestrus / Ovulation

Source Information SUMMARY: Hedgehogs are seasonally polyoestrous. Data from one study indicate that many matings do not result in conception but a period of pseudopregnancy prior to the next oestrus; several cycles of oestrus and pseudopregnancy may occur before conception. Following gestation and birth there may be a period of lactational anoestrus although a post-partum oestrus has sometimes been described. Early loss of a litter is likely to result in rapid return to oestrus and fertile mating. In autumn females enter a period of seasonal anoestrus.
  • Hedgehog sows are seasonally polyoestrous (i.e. they undergo a number of repeated oestrus cycles during their breeding season).(B228.8.w8)
  • A study of the reproductive tract of female hedgehogs showed that they are seasonally polyoestrous. Ovulation is spontaneous (confirmed by records of ovulation occurring in the laboratory). Data indicated that if mated, females often do not conceive and undergo a period of pseudopregnancy then a return to oestrus; this cycle may be repeated several time before pregnancy results from mating. Females have been shown to conceive twice in one year by the observation of pregnancy in individuals which also have well-developed, recently-functional mammary glands; ovulation has been recorded in recently-pregnant individuals, indicating a return to oestrus following pregnancy. (J68.223.w1)
  • Sows undergo a period of anoestrus prior to puberty and seasonally outside the breeding season.(B228.8.w8)
    • The ovary is very small during the period October to April; its size increases rapidly in spring. (B289.3.w3)
    • Both active females in September and November and hibernating females in January are in anoestrus, as shown by histological studies. In March-April after about five months of hibernation histological changes of proliferation are visible in the endometrium and the vagina is hypertrophied. If animals are maintained in hibernation into May (after 6.75 months hibernation), the uterus has undergone further proliferative changes, vaginal changes have continued and some follicles in the ovaries are nearly mature. (J200.5.w2)
    • Activation of the reproductive system appears to start later during the hibernation season in the female hedgehog than in the male. (J200.5.w2)
  • Hedgehog sows are spontaneous ovulators, requiring no stimulation from mating to induce ovulation as occurs in some other mammal species.(B142, B228.8.w8, B289.3.w3)
  • Mature follicles typically measure approximately 1 mm (range 0.7-1.25 mm) at the point of ovulation.(B228.8.w8)
  • If no mating accompanies ovulation, the hedgehog sow will undergo a short period of dioestrous during which the corpora lutea remain "small, fibrous and hardly luteinized". (B228.8.w8)
  • Hedgehogs undergo a period of pseudopregnancy, following ovulation and infertile mating, when the corpora lutea develop and secrete progesterone (in the same manner as during pregnancy) for approximately 7 - 10 days before the subsequent oestrus cycle ensues.(B228.8.w8)
  • Ovarian luteal and follicular activity, ovarian and uterine development regress significantly during the winter seasonal anoestrus period. (B228.8.w8)
  • Uterine lining and accessory glandular tissue development occurs from as early as March, before the onset of oestrus cycle activity.(B228.8.w8)
  • The vaginal epithelium develops and becomes cornified prior to ovulation. The cornified layer persists throughout dioestrus but is shed after mating and at beginning of gestation when it becomes thin in nature.(B228.8.w8)
  • Conception may not occur until after several (three to five) oestrus cycles. (B289.3.w3)
  • Mating often does not occur with the first oestrus cycle of the breeding season and several cycles of pseudopregnancy (2 or 3) may typically occur before conception is achieved. Whilst levels of fertility at the beginning of the breeding season may be variable, the adaptive significance of the apparent level of infertility is unclear.(B228.8.w8)
  • Evidence to date has found no association between "age, reproductive history, low body weight or low uterus weight" and patterns of pseudopregnancy.(B228.8.w8)
  • Although post partum oestrus has been documented in the hedgehog sow, other authors have cited evidence for an anoestrus period at the beginning of lactation.(B228.8.w8)
    • A return to breeding condition and fertile mating following soon after the birth of a litter is more likely to occur if the litter is lost/removed shortly after birth. In one instance following removal of the litter a female gave birth 38 days later. (J46.136.w1)
  • The maximum number of ova released per ovulation in one study was ten.(B228.8.w8)

(B142, B228.8.w8, B289.3.w3, J46.136.w1)

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Mating / Gestation / Pregnancy

Source Information SUMMARY: Gestation has been calculated to last about 35 +/- 4 days; occasional records indicate the possibility of pregnancies lasting more than 40 days; this may be related to adverse environmental conditions triggering a period of torpor during (early) pregnancy. Hedgehog embryos are evenly distributed between the two horns of the uterus and post-implantation losses appear to be low.
  • Many matings do not end in a successful pregnancy.(B228.8.w8)
  • Mating often does not occur with the first oestrus cycle of the breeding season and several cycles of pseudopregnancy (2 or 3) may typically occur before conception is achieved. Whilst levels of fertility at the beginning of the breeding season may be variable, the adaptive significance of the apparent level of infertility is unclear.(B228.8.w8)
  • Studies of the reproductive tract of female hedgehogs have shown that mating often does not result in pregnancy; it appears to be usual for several cycles of oestrus, pseudopregnancy and return to oestrus to occur before a successful pregnancy. (J68.223.w1)
  • The degree of intraspecific variation for estimates of the gestation period for Erinaceus europaeus exceeds quoted interspecific variation within the Erinaceinae (Erinaceidae - Hedgehogs, moonrats (Family)).(B228.8.w8)
  • Gestation length is estimated to range between 35+/-4 days, although outlier observations in excess of 40 days exist in the literature.(B228.8.w8)
  • Minimum probably 34-35 days and maximum probably 39 days: Females gave birth up to 37 days after capture and at a minimum of 36 days after being placed in a breeding pen with a male. (J46.136.w1)
  • Estimated gestation length is 31-35 days. The shortest time between introduction of a female to a breeding pen with a male and subsequent parturition was 31-32 days. (B271.29.w29)
  • Gestation period is approximately 34 days (B260.6.w6, B261) with variation of up to 4-5 days (B260.6.w6); 31-35 days.(B142, B147); 31-37 days.(B144); 35 days.(B285.w1)
  • Variation in estimates of gestation period may be due to incomplete data sets.(B228.8.w8)
  • Although no supporting evidence is available, it has been postulated that in response to adverse environmental factors (e.g. cold ambient temperature and reduced food availability), a sow may undergo a period of torpor that could delay gestation.(B228.8.w8, B254.15.w15, B260.6.w6)
  • Hedgehog embryos are able to migrate between the two uterine horns prior to implantation which ensures even distribution.(B228.8.w8)
    • Studies of the reproductive tract of female hedgehogs have shown that the number of embryos is the same in each uterine horn, or one horn contains only one more embryo than the other. (J68.223.w1)
  • The chorioallantoic placenta of the hedgehog is typical of that for the Insectivora - Insectivores (Order) and is discoidal and haemochorial in anatomical design.(B228.8.w8)
  • Pregnancy diagnosis by abdominal palpation is reported to be impossible in the conscious sow. However if the hedgehog is under general anaesthesia, palpation and differentiation of a gravid uterus from a full urinary bladder may be possible with considerable experience and care, through refection of the latter organ.(B228.8.w8)
  • Despite multiple matings, many sows do not become pregnant, and "a fair proportion may escape becoming pregnant altogether."(B254.14.w14)
  • Death and resorption of fetuses following implantation appears to be uncommon: only four of a total of 42 pregnant females in one study contained such fetuses, with loss of the whole litter in two cases (four and two fetuses respectively) and of a single fetus from the litter in two other females. The percentage mortality of embryos from 53 pregnancies was 3.3% (8/242). (J46.136.w1)

(B142, B147, B228.8.w8, B254.14.w14, B254.15.w15, B260.6.w6, B261, B271.29.w29, B285.w1, J46.136.w1)

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Parturition / Birth

Source Information SUMMARY: Births may occur in Britain from May (rarely April) to September or even October. Sows construct a breeding nest or burrow within which they give birth. There have been few observations of parturition; disturbance around the time of birth carries a high risk of maternal cannibalism. Hoglets may be born in anterior (head first) or posterior (tail first) presentation. The fetal membranes and placenta from each neonate are eaten by the mother who moves her offspring carefully with her mouth and positions them by or under her belly.

Parturition:

  • As parturition approaches and begins, hedgehog sows become particularly sensitive to disturbance which can lead to neonatal desertion, infanticide or cause the mother to eat her offspring.(B228.8.w8)
  • Hedgehog sows give birth within a breeding nest or burrow which they have constructed.(B228.8.w8, B262.10.w10)
  • Observational reports of hedgehog parturition are few; births monitored in captivity have been associated with maternal cannibalism of young.(B228.8.w8)
  • Observations of parturition have noted variation in sow posture; standing with hind limbs positioned apart, laying on her side, resting on the belly with forelimbs extended and hind limbs elevated.(B228.8.w8)
  • One description reported the sow lying partially on her side then rolled up prior to the birth of the first young. (B258.w7)
  • Hoglets can be born in anterior (head-first) or posterior (rear-first) presentation within the amniotic sac.(B258.w7, B228.8.w8)
  • The first set of spines usually do not penetrate the neonatal skin at the point of birth and therefore do not present a potential risk to the maternal birth canal.(B228.8.w8)
  • The sow removes and eats the fetal membranes and placenta from each neonate and positions the offspring by, or underneath, her belly, moving them by carefully holding them with her mouth. (B258.w7, B228.8.w8)
  • Duration of parturition may vary between a "few minutes to several hours."(B228.8.w8)
  • If the sow and boar are artificially confined together during parturition, the boar may cannibalise his offspring.(B228.8.w8)
  • Production of very large hoglets (including one individual 24.5g) has been recorded associated with protracted delivery, stillborn hoglets and maternal death a few days later. (J23.6.w1)

Seasonality:

  • Whilst hedgehogs can be born between from May to October, the majority are born in May to July.(B142, B254.15.w15, B261)
  • Hedgehog births occur with two distinct peaks; the first in May to July and the second in September.(B142)
  • It has been suggested that late hedgehog litters in Britain are most likely to represent breeding attempts by sows which have not successfully raised a litter earlier in the season, for whatever reason e.g. abortion, nest disturbance.(B228.8.w8)
  • In geographical areas with longer breeding seasons than in the UK (e.g. New Zealand, central and southern Europe), it is likely that hedgehog litters born late in the season do represent second broods.(B228.8.w8)
  • In geographical areas with shorter breeding seasons than in the UK (e.g. Fennoscandia (Finnish-Russian-Norwegian border)), late hedgehog litters do not occur and only single broods can be reared.(B228.8.w8)
  • Surveys suggest that post-implantation embryonic and fetal losses are low since average numbers of ovulations closely mirror the observed number of fetuses.(B228.8.w8)

(B142, B228.8.w8, B254.15.w15, B261, B262.10.w10, J23.6.w1)

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Neonatal Development

Source Information SUMMARY:
  • At birth hoglets are hairless, pink, with sealed eyes and ears and no spines, about 70 mm (+/- 15mm) long and 8-25 g in weight.
  • The first white spines appear within the first day of birth. The second, pigmented, set of spines begin to emerge at 36-48 hours after birth and are the main spines by two to three weeks; these are replaced by the first adult spines from about six weeks old. 
  • Hoglets are able to roll up partially by 11 days and fully by about 28 days. 
  • The eyes and ears open at about two weeks old; fur is growing on the body by about this time. Thermoregulation is poor before two weeks old but is fully developed by about 27-32 days.
  • Teeth start to erupt by about 20-21 days. They first take solid food at about 21-23 days and are fully weaned by 38-44 days old.
  •  Body weight may double in the first week, reaching six times birth weight by three weeks and 200-235 g by six weeks.

Birth: 

  • Following birth, hoglet neonates are hairless, pink in colour with their eyes and ears sealed closed.(B228.8.w8, B254.14.w14, B260.6.w6, B261, B255.4.w4)
  • Birth weight is reported to be between 12-25 g / 0.4-0.9 oz (B258.w7, B52); 10-25 g (B142); 12-25 g /0.4-0.9 oz (B144); about 15 g (B147); 8-25.14 g. (B255.4.w4); 8-22 g average 15 g for live births, maximum 24.5 g for one born dead. (J23.6.w1)
  • At four days old 10-40 g average 26.5 g, by seven days old average 40 g and by weaning at 40 days 125-345 g, average 235 g. (B255.4.w4)
  • Neonatal body length varies between 70 +/- 15 mm and body weight between 8-25 g.(B228.8.w8)
  • Neonatal body length reported to be 5.5-9.5 cm. (B258.w7); 
  • Length at birth 56-96 mm (B255.4.w4)
  • Neonatal size varies with litter size and between litter mates.(B228.8.w8)

Collation of source data from a number of authors suggest the follow ages at which certain key developmental stages are reached: ability to roll up partially (11 days), eyes open (12, 14-18days), growth of fur on the body (14 days), exploration outside the nest begins (19-24 days), eruption of first teeth (20-21 days), ability to roll up completely (28 days), first takes solid food (21, 23 days) and fully weaned (38-44, 42 days old).(B228.8.w8) 

Spines:

  • At birth the pink skin of the hoglet is taut and distended with fluid, having a bloated appearance and is covered with "pimples" which correspond to the points of emergence of the first set of spines.(B228.8.w8, B255.4.w4, B258.w7) These are unpigmented and white in appearance and number approximately one hundred in total.(B142, B228.8.w8, B254.15.w15, B260.6.w6, B262.10.w10)
  • The skin appearance changes rapidly from the first hour of life and gradually "deflates" to a soft and wrinkly state over 24 hours, during which time the first set of spines emerge.(B228.8.w8, B258.w7, B262.10.w10)
  • The first set of spines are not soft as is sometimes reported, but their points are sharp when dry and provide some level of defense to the youngster.(B228.8.w8)
  • The first set of spines are soft but soon harden. (J23.6.w1)
  • The first set of spines (approximately 7 mm long) are different in morphology from the latter sets in that have weak roots and the thin neck at the spine base is absent.(B228.8.w8)
  • The first set of spines are shed gradually from when the hoglet reaches approximately one month of age.(B228.8.w8)
  • A 'parting' line devoid of spines is present in the hoglet and extends form the midline of the brow over the dorsum of the spine to the rump area.(B258.w7, B228.8.w8, B254.15.w15, B255.4.w4) This dividing line corresponds to the embryological development of the orbicularis musculature.(B258.w7, B228.8.w8)
  • Whilst the first set of spines do not usually emerge from the skin prior to birth, some reports describe that spines may protrude slightly, dependent on the duration of parturition and maturity of the neonate.(B228.8.w8)
  • The second set of hedgehog spines begin to emerge from 36-60 hours old (B228.8.w8, B255.4.w4) and reach a length of 12-15 mm.(B228.8.w8)
  • Hedgehogs have three generations of spines in their lifetime.
    • The first set of spines are unpigmented and present at birth. (B228.2.w2, B228.8.w8)
    • The second generation of spines are pigmented, begin to emerge at 36-48 hours of age, and obscure the first generation spines by two to three weeks of age. (B142, B228.2.w2, B228.8.w8)
    • The third generation, or adult, spines gradually replace the smaller second set spines from the time of independence at approximately six weeks old. (B228.2.w2, B228.8.w8, B291.12.w12)
    • Shedding of the first and second sets of spines starts at about 40 days old. (J23.6.w1)
    • Adult spines are shed constantly. (B291.12.w12)

Rolling and spine erection:

  • Young hoglets are unable to roll up into a ball for protection but instead will "jerk their bodies upwards to jab their spines into the intruder" and emit calls and 'huffing' noises.(B228.8.w8)
  • The ability of hoglets to bristle and erect their spines begins from approximately one week of age.(B258.w7, B228.8.w8)
  • Hoglets become able to roll up into a loose ball from around two weeks old (B228.8.w8); 11 days old (B142, B255.4.w4, B260.6.w6); twelve days old (B258.w7); two to three weeks.(B285.w1)

Eyes and ears:

  • The eyes are closed in new-born hoglets. (B289.3.w3)
  • The eyes and ears of hoglets open at approximately two weeks old (B142, B228.8.w8, B254.14.w14, B255.4.w4, B260.6.w6, B261); hedgehog eyes open at approximately 10 days of age (B262.10.w10); eyes open about 14-18 days old (B258.w7); earliest open eyes recorded at 13 days, most open by 15-16 days, occasionally still closed at 20 days. (J23.6.w1)

Thermoregulation:

  • The ability to thermoregulate before two weeks of age is reported to be poor, developing to full function at 27-31 days old.(J180.26.w1, B228.8.w8)

Growth rate/weight gain:

  • Monitoring of the growth rate of hoglets in captivity has shown that their body weight can increase two-fold from birth within the first week of life, six-fold by 21 days old and approximately ten-fold by 40 days old (200-235 g).(B228.8.w8)
  • Weight gain: at 4-4.5 days old range 10-40 g, mean 26.5 g (n=54); at seven days old range 21.5-61.5 g, mean 40 g, indicating increase of 2-3 times initial weight during the first week. Increase of 7-8 times by three weeks old. Range 125-345 g by 40 days. (B271.29.w29)
  • Variation in growth rates between individual hoglets increases from the time that they begin to take food independently.(B228.8.w8)
  • The increase in body weight may slow at the time of weaning but subsequently remains high since young hedgehogs need to increase their body weight two-fold after weaning in order to survive winter hibernation.(B228.8.w8)
  • Studies of the fusion of epiphyseal zones of the hedgehog forelimb suggest that growth may continue until 18 months of age.(B228.8.w8)
  • Maximal body size is thought to be reached by the age of 2-3 years old.(B228.8.w8)

Tooth development:

  • Deciduous teeth begin to be replaced from three weeks until approximately four months of age.(B254.14.w14, B285.w1)
  • Deciduous teeth begin to erupt at about 14 days with permanent teeth erupting from about eight weeks old. (B291.12.w12)

Feeding, exploration and dispersal:

  • Sows first begin to take their litters out of the nest from three weeks of age to learn independent foraging.(B142, B260.6.w6, B261)
  • Finding and eating food by three to four weeks old but suckled to about 40 days old. (B258.w7)
  • Young hedgehogs become independent from six weeks old when they disperse from their siblings and dam (B228.8.w8, B260.6.w6); weaned and independent from four to six weeks old (B142, B261); weaned from approximately six weeks.(B285.w1)
  • Average youngster body weight at the time of independence from the dam is 250 g.(B261)
  • At the point of independence, hedgehogs have poor insulation and often experience difficulties in finding sufficient food. As a consequence, youngsters may become active during the day and develop ill co-ordinated movement with high levels of mortality during the first winter.(B262.10.w10)
  • Juvenile hedgehogs are found in an even sex ratio.(B142, B228.2.w2)
  • Radio-tracking work in Norway found no difference in dispersal date or body weight at dispersal between male or female juvenile hedgehogs.(P35.3.w13, P35.4.w14)
    • Results suggest that juveniles must reach a threshold body weight before they leave the breeding nest.(P35.4.w14)

(B52, B142, B144, B147, B228.8.w8, B254.14.w14, B258.w7, B260.6.w6, B261, B262.10.w10, B271.29.w29, B285.w1, B289.3.w3, P35.3.w13, P35.4.w14)

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Litter Size

Source Information SUMMARY: Litter size in Britain averages four to five at birth. The range of litter size recorded is two to 10. About 20% of hoglets may die prior to leaving the nest.
  • Average hedgehog litter size in UK is four to five hoglets (B228.8.w8, B254.15.w15, B260.6.w6, B261, B262.10.w10, B285.w1); litters as small as two and as large as six or seven hoglets can be born.(B254.15.w15, B260.6.w6)
  • Total ranges of two to 10 with examples from different studies of: mode 3-8, range 3-5 average 3.86 from seven litters; 4-5, maximum seven from 67 litters; 4-8; 4-7; 4.75 mode 4-6 range 2-9; two; 2-3 corpora lutea; average 3.0 from 113 litters; mean 5.2 at weaning (n=85), range 5-8, mean 6.0 from n=3, 6.8 range 5-8 (n=4 litters). (B287)
  • Studies of the reproductive tract of female hedgehogs have shown that from the two ovaries 3-10 ova may be matured at one time, with an average of five. (J68.223.w1)
  • Average litter size in captivity three (339 young from 113 litters). (B271.29.w29)
  • Litter size range between two and 10. (B144)
  • Litter size in Britain is two to nine but averages five. (B255.4.w4)
  • Average litter size four to six. (B142)
  • Three to seven, with five most common. (B289.3.w3)
  • Two to ten, average seven. (B258.w7)
  • Number of embryos ranges between 2 and 7; average values from surveys recorded as 5.0 and 4.6 per litter. Embryonic losses are though to be low. (B142)
  • Average hedgehog prenatal litter size in one study was 4.6 (n=53 pregnancies). (J46.136.w1)
  • Average number of early hedgehog nestlings in one study was 4.4 (n=11 litters). (B228.8.w8)
  • Average 4.25 nestlings per litter (323 from 76 maternal nests) in one study in the UK. (J46.182.w1)

  • Fall in mean litter size from 4.37 at the "early young" stage (less than two weeks old) to 3.72 in young "seen with adult" at about 3-5 weeks old indicates some mortality (calculated as 19.3%) prior to weaning, although some of the apparent decrease may be due to partial dispersal of young from the litter. (J46.182.w1)

    • The figures do not allow for whole litters lost without record (as may occur if the female is disturbed in the first few days after parturition). (J46.182.w1)

    • A greater proportion of litters of "early young" contain five or six hoglets than do litters of "late young", indicating probable higher mortality among litters of larger original size. (J46.182.w1)

  • Variation in litter size with relation to climate may occur. (B228.8.w8)
  • Mortality of hoglets can occur in large litters because of limited maternal milk reserves which cannot supply all offspring demands. (B262.10.w10)
  • Approximately one in five hedgehog nestlings die before emergence from the nest (B254.14.w14, B254.24.w24, B260.6.w6, B262.10.w10)
  • In the UK, work has recorded hedgehog perinatal mortality rates of approximately 5%. Approximately a further 19% of the surviving youngsters are believed to die prior to weaning. (B228.9.w9)
  • It is estimated that a sow may successfully rear on average two, perhaps three young, per year (B254.15.w15); sows successfully rear three hoglets on average per litter. (B260.6.w6)
  • Litter sizes in Sweden are higher than those in Britain (average 5.2 individuals per litter, compared with average 3.7 per litter in Britain. It was suggested that this may be an adaptation to a shorter breeding season, which lasts only two months in Sweden; it is possible for female hedgehogs in Sweden to produce only one litter per season, while it is theoretically possible for those in Britain to produce two. (J180.26.w2)
  • Data from hedgehogs captured for breeding in captivity indicate that litters born early in the season after a long hard winter may be smaller than those born later in the year. (J23.6.w1)
  • Studies of litter size at various ages have been used to estimate pre-weaning mortality in the hedgehog. (P35.3.w8)
  • Data from a capture-mark-recapture study in Sweden found that the average number of juveniles per female in the population was 2.8. (J46.220.w1)

(B142, B144, B228.8.w8, B228.9.w9, B254.14.w14, B254.15.w15, B254.24.w24, B260.6.w6, B261, B262.10.w10, B271.29.w29, B285.w1, B287, B289.3.w3, P35.3.w8 , J46.136.w1, J46.182.w1, J180.26.w2)

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Time between Litters/ Litters per year

Source Information SUMMARY: In central and southern Europe, where the breeding season is longer, and in New Zealand, females may raise two litters in a single breeding season. In Britain it is probably rare that a female conceives, lactates and weans one litter then successfully repeats the process; one such instance has been recorded in captive hedgehogs (litters born May and August and weaned at 43-45 and 42 days respectively). Late litters in females showing evidence of prior lactation in the same season are probably more commonly due to early loss of the first litter. In geographical areas with a shorter breeding season, such as Sweden, only one litter is possible per year.
  • Whilst it is theoretically possible that hedgehogs could give birth and rear two litters in a single breeding season, no proof is available since this has not been documented to date in a monitored individual. (B228.8.w8, B260.6.w6)
  • Studies of the reproductive tract of female hedgehogs have not shown any indications of an immediate post-partum oestrus and most animals with well-developed mammary glands were in lactational anoestrus. Individuals were found (from July onwards) which were undergoing their second pregnancy for that year (one animal pregnant and with a well-developed and recently-functional mammary gland) or (several animals) ovulating having been pregnant previously in that year. As with a first pregnancy it appeared that one or more cycles of infertile mating and pseudo-pregnancy occurred before conception. (J68.223.w1)
  • It has been suggested that late hedgehog litters in Britain are most likely to represent breeding attempts by sows which have not successfully raised a litter earlier in the season, for whatever reason e.g. abortion, nest disturbance. (B228.8.w8)
  • It is possible for sows to produce subsequent litters in a single season after raising their first family. (B262.10.w10) 
    • Second litters are not produced by all females; for instance sows in the year after their birth may not reach sufficient body size until late in the season, making it unlikely that they would produce two litters in that year. (B262.10.w10)
    • Mortality rates are likely to be high in the first few months of life for late-born second litters. (B262.10.w10)
  • Reports exist in the literature that hedgehogs may sometimes produce second litters in a single year. (B52, B142)
    • "A female hedgehog produces annually on average two litters."  (B258.w4)
    • "Many females also produce two litters in a summer and manage to rear the second brood." (B258.w7)
  • Sows which rear their first litter early in the breeding season, or who lose their first litter for whatever reason, may produce a second litter. However these late litters are not likely to be born before September and may even be born as late as October with poor chances of survival. (B254.15.w15)
  • One pair of captive hedgehogs in the UK produced a litter of four in May, all four being raised to weaning at 43-45 days, with a second litter born in August, all three hoglets from this second litter being raised to weaning at 42 days. (J19.41.w1).
  • In captivity, sows may have up to three litters in a season, if early litters are lost. (B271.29.w29, B260.6.w6, J23.6.w1)
  • In geographical areas with longer breeding seasons than in the UK (e.g. New Zealand, central and southern Europe), it is likely that hedgehog litters born late in the season do represent second broods. (B228.8.w8)
  • In geographical areas with shorter breeding seasons than in the UK (e.g. Fennoscandia (Finnish-Russian-Norwegian border)), late hedgehog litters do not occur and only single broods can be reared.(B228.8.w8)
    • In Sweden the main breeding season lasts for only about two months. (J180.26.w2)

(B52, B142, B228.8.w8, B254.15.w15, B260.6.w6, B262.10.w10, J180.26.w2)

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Lactation / Milk Production

Source Information SUMMARY: Lactation lasts about four to six weeks. Immunoglobulin absorption in the gut of the hoglets continues for at least 20 days and possibly 30 days or longer. Hedgehog milk is highly concentrated, rich in protein and fat and low in lactose.
  • Duration of lactation is approximately 4-6 weeks (B142); 38-45 days (B147); 45-50 days. (B144)
  • Observation of a single wild sow during parturition revealed that neonates began to suckle within a few minutes of their birth.(B228.8.w8)
  • The posture adopted by the sow and hoglets during suckling has been variously reported in the literature; reports include the sow lying on her side for suckling (Erinaceus europaeus), hoglets resting in dorsal recumbency (belly facing upwards) under the flanks of the sow (Atelerix albiventris - Four-toed hedgehog), the "female places the young on her belly where they begin to suckle" (Erinaceus europaeus - single report only).(B228.8.w8)
  • Development of the mammary glands occurs in pregnant and lactating sows where strips of mammary tissue can be palpated, extending from the axillae (armpit) to the inguinal areas (groin).(B228.2.w2, B228.8.w8)
  • Hedgehogs receive passive transfer of immunity with antibodies from the maternal milk.(B228.8.w8)
    • There is no transfer of passive immunity through the placenta. (J9.184.w1, J179.152.w1)
    • Studies have shown that the antibody titre in first milk may be similar to that found in maternal serum but by six days into lactation it has declined to 25% of maternal serum titre. (J9.184.w1, J179.152.w1)
    • Titres in the young remain much lower than those in the dam. (J179.152.w1, J179.154.w1)
    • The gut of the young continues to take up antigen for at least 20 days after birth and probably as long as 30 days. (J179.154.w1, J179.158.w1)
    • The gut of suckling hedgehogs is capable of taking up agglutinins (antibodies) other than those of hedgehogs, as shown by uptake of agglutinins from sera of other species (rat, rabbit, guinea-pig and cattle) fed to suckling hedgehogs. (J179.158.w1)
    • Absorption of antibody was greatest from sera containing mainly gamma-globulin. (J179.158.w1)
  • Data regarding hedgehog milk composition is scant; sample analysis revealed 79.4% water by weight, 10.1% fat, 2.0% carbohydrate, 7.2% protein and 2.3% minerals although no information regarding the stage of lactation at which the milk was taken, or the number of samples within the data set, was available.(B228.8.w8)
  • A study using milk collected from four females, suckling 3-5 young each, for the whole period of lactation, found that it was very concentrated, being 45.2% (mean) dry matter (DM). It was protein rich (16.6 g/100 g milk) and fat-rich (25.5 g per 100 g milk), but contained only traces of lactose (mean 0.07 g/100 g milk). Within the fatty acids long-chain and unsaturated fatty acids (C18:1 and C18:2) predominated. About 98% of fatty acids contained more than 16 carbon atoms and 78% of these were unsaturated Predominant fatty acids were oleic (37%), linoleic (27%) and palmitic (21%) acids. The protein included high levels of sulphur-containing amino acids: methionine and cystine were found at 6.4 g/100 g amino acids compared to about 3.8 g/100 g amino acids in cows' milk. Leucine and lysine were predominant among the essential amino acids. Macro and trace element concentrations were high in comparison to milks from domestic animals. (J191.80.w1)

(B142, B144, B147, B228.2.w2, B228.8.w8, J9.184.w1, J179.152.w1, J179.154.w1, J179.158.w1, J191.80.w1)

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Sexual Maturity

Source Information SUMMARY: Sexual maturity may occur at about nine to 12 months old in the wild, i.e. in the year following birth, and possibly as young as six months in captivity. Pregnancy has been recorded rarely in females weighing as little as 400 g but more usually 550-600 g or higher.
  • Sexual maturity can occur earlier in captivity than in the wild populations, probably from as young as six months of age.(B228.8.w8)
  • It is thought to be unlikely that hedgehogs within wild free-ranging populations would breed in the season of their birth.(B228.8.w8)
  • Hedgehogs do not become sexually mature in the same year as their birth.(J68.223.w2, B254.14.w14, B260.6.w6, B271.29.w29, B289.3.w3)
  • Studies of the reproductive tract of female hedgehogs indicated that females do not become capable of breeding in the year of their birth. Immature females weighing 400-500 g in September/early October have a small uterus and although a single corpus luteum (indicating ovulation) was found in one such animal it was considered extremely doubtful that pregnancy would result in such an individual. (J68.223.w1)
  • Studies of the reproductive tract of male hedgehogs found individuals classed as "definitely immature" between July and May; it was estimated that males reach sexual maturity no sooner than nine months old, in the breeding season following the year of their birth. (J68.223.w2)
  • Hedgehogs have their first litter in the year after their birth with sexual maturity at about 11 months old.(B142)
  • A capture-mark-recapture study in Sweden found that no subadult females had suckled young; it was assumed based on this finding that females did not reproduce before they were adult. (J46.220.w1)
  • Sexual maturity is estimated to occur between 9-11 months of age.(B228.8.w8); at ten months.(B147); at 12 months.(B144)
  • Hedgehogs may produce litters up to at least six years of age.(B260.6.w6)
  • Sexual maturity has been variously reported as five months in captivity, nine months in the wild, 10-12 months, and for females first parturition at 11 months or one year old. (B287)
  • First fertile matings by 11 months. (B271.29.w29)
  • Lowest body weights at which females have become pregnant recorded as 550-600 g, but more usually over 600 g and mainly over 700 g in captivity. (B271.29.w29)
    • A female weighing only 400 grams was found to be pregnant in studies of the reproductive tract of female hedgehogs; ovulation was recorded rarely in spring in females under 400 g (one as low as 320 g). (J68.223.w1)

(B142, B144, B147, B228.8.w8, B254.14.w14, B260.6.w6, B271.29.w29, B287, B289.3.w3, J46.220.w1, J68.223.w1)

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Male Seasonal Variation

Source Information SUMMARY: The reproductive tracts of male hedgehogs show considerable seasonal changes.
  • Studies have identified circadian and seasonal variation in the level of plasma testosterone, luteinizing hormone, melatonin, beta-endorphin, thyroxine, cortisol and prolactin in hedgehog plasma.(B228.8.w8)
  • During the first half of hibernation spermatogenesis reaches only the primary spermatocyte stage. (J68.223.w2, , J206.81.w1)
  • During the latter half of hibernation, the boar begins to secrete luteinizing hormone, in turn stimulating production of testosterone from the Leydig cells within the testes. This activity occurs approximately one month before the onset of spermatogenesis in the seminiferous tubules. The reverse sequence of timing occurs at the end of the breeding season.(B228.8.w8)
  • Concentrations of testosterone in the plasma and a testosterone binding protein are inversely related during the year.(B228.8.w8)
  • Testes temperature is maintained at on average 1.4+/- 0.2C below body temperature during the active season but not during hibernation. Hedgehogs have a layer of insulating and poorly vascularised fat which surrounds each testicle and are thought to employ a countercurrent heat exchange system for testicular cooling, as in other species.(B228.8.w8, J206.81.w1)
    • A study using simultaneous telemetry of the temperature of the body and the testes of male hedgehogs showed that during the time when hedgehogs are active (non-hibernating), the testes are maintained at a temperature averaging 1.4+/- 0.2C below body temperature. Testis temperature was maintained in the range 34.0-34.9C even when the body temperature rose to 36.2C. During hibernation the difference between body and testis temperature was variable and reached up to 1C warmer (mean daily temperature) than the body. (J206.81.w1)
  • Plasma testosterone levels rise rapidly in spring, peaking between February and April. Levels fall sharply in August, remain low through the first half of winter. (J206.84.w1)
  • Testis development precedes accessory gland development in the immature animal and sperm production precedes development of the accessory sex glands at the beginning of the breeding season. (J68.223.w2, B228.8.w8)

B228.8.w8, J68.223.w2, , J206.81.w1, J206.84.w1

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Longevity / Mortality

Source Information SUMMARY: In the wild hedgehogs which reach five years old are considered to be "old" and maximum lifespan is probably six to eight years. In captivity 10 years may be reached and as high as 14 years has been reported. Average life expectancy in individuals which survive to weaning is probably two years. 
  • "Many [hedgehogs] live to be 3 years old, a few reach 7, but it is unlikely that more than 1 in 10,000 lives to be 10 years old."(B262.10.w10)
  • "Probably about four hedgehogs in a thousand might reach ten, but it must be rare indeed for any hedgehog to survive longer than that."(B254.24.w24)
  • "Old age" for a wild hedgehog is though to be approximately five years.(B260.7.w7, B261)
  • In the wild hedgehogs rarely pass five years of age; longer life spans may be seen in captive hedgehogs. (B291.12.w12)
  • The maximum age for a hedgehog is estimated to be approximately ten years old.(B142, B260.7.w7)
  • "Population turnover time" estimated to be eight to nine years.(B142)
  • Hedgehogs can live for seven years or more in the wild and in captivity.(B142, B147)
  • May live eight to 10 years in captivity. (B258.w7)
  • Maximum recorded age in captivity is ten years. (B255.6.w6)
  • A hedgehog has been reported to live to 14 years in an enclosed garden. (D82)
  • There is a report of a hedgehog in captivity in Germany reaching 16 years old. (B257.1.w2)
  • Lifespan 8 years.(B144)
  • Studies of hedgehogs in both Sweden and Britain suggest that average life expectancy after weaning is approximately two years.(B228.9.w9, B254.22.w22)
    • Approximate life expectancy at weaning calculated at just over two years in Sweden, compared with 1.9 years in Britain. (J180.26.w2)
    • A capture-mark-recapture study in Sweden found the average yearly mortality rate to be 47% for non-juveniles and 34% for juveniles. (J46.220.w1)
  • A capture-mark-recapture study in Sweden found an average of 2.8 juveniles per adult female in the population. Given an estimated litter size at birth of 6.5 the mortality rate from birth to catchability was 0.57. (J46.220.w1)
  • Consensus of data from the literature estimates maximum lifespan in the wild to be between six and eight years.(B228.9.w9)
  • The maximum recorded age of a captive hedgehog is ten years.(B228.9.w9)
  • Study results from England and Germany investigating mortality rates of hedgehogs within their first year (60-70% or 70-80% respectively) and of adults (30% or 20-40% respectively) produced comparable results.(B228.9.w9)
  • Mortality rates are estimated as 20-30% for adults but 60-70% during the first year following leaving the nest. (B341.3.w3)
    • Death from starvation during hibernation is probably the principle cause of death, with badger predation a contributing factor. (B341.3.w3)
  • It is estimated that less than one third of first year hedgehogs survive to a second year; however approximately two-thirds of the adult population survives from one year to the next.(B254.24.w24)
  • Decline in adult survival rates is believed to occur from 4-5 years old.(B142)
  • Hedgehog survival rates have been observed to vary within the species' geographic range according to local climate: calculated survival percentages were highest in New Zealand, intermediate in the UK and lowest in the harsher climate of Sweden.(B228.9.w9, J46.220.w1)
  • Using estimates of percentage total weight loss during hibernation, it has been predicted that first year hedgehog juveniles must reach a body weight of approximately 450-550 g to survive hibernation over winter. (J46.203.w1, B228.6.w6, B254.16.w16, B262.8.w8)
  • It is estimated that winter mortality rates of late litter small juvenile hedgehogs may approach 100%.(B262.12.w12)
  • A study in Finland found the oldest animals to be females in their sixth and seventh winters. (J200.8.w1)
  • In general it was considered that environmental factors were more important than density-dependant factors in affecting mortality in Sweden. (J46.220.w1)
    • A capture-mark-recapture study in Sweden found that for juveniles winter mortality averaged at 33% but with a range of 6%-94%. Mortality was not significantly correlated with environmental variables however surviving animals had been heavier than their non-surviving counterparts in autumn; this was statistically significant for juvenile males. (J46.220.w1)
    • A capture-mark-recapture study in Sweden found that for non-juveniles winter mortality averaged at 33% with a range of 26%-43%. Mortality was highest in winters with temperatures much lower than average and with the number of days with a minimum temperature of freezing or lower. Mortality of sub-adults was also correlated with population density. (J46.220.w1)
    • A capture-mark-recapture study in Sweden found that for non-juveniles animals found dead due to road traffic accidents were 3-22% of the population (J46.220.w1)
  • Hedgehogs are vulnerable to a variety of environmental and man-made threats during hibernation e.g. floods, cold, nest destruction.(B254.25.w25, B260.7.w7)
  • One study in Flanders found that at least 45/70 (64%) marked animals survived hibernation, including 72% of 54 adults but only 38% of 16 juveniles. Confirmed traffic mortality included 3/48 animals (6.2%) in July-August 1997 and 1/62 (1.6%) of animals in 1998. (J211.42.w5)
  • A study in the Netherlands found that hedgehogs were commonly killed on roads, constituting more than 5% of animals found killed on roads and in some areas more than 25% of mammals found. Hedgehog mortality on roads was highest in June to August: the peak of the mating season when hedgehogs, particularly males, are most active. Numbers of hedgehogs killed per length of road varied from 0.3 to 2.9 individuals per kilometre per year; this was considered a low estimate, as animals may have been removed by scavengers or ended up unseen in the vegetation of the verge. (J211.42.w3)

A variety of age estimation techniques have been described for hedgehogs. Timings of dental eruption, and dental attrition, are not considered accurate, nor is body weight. The dry weight of the lens from the eye may be used but required fresh material collected at post mortem examination. Radiographic studies can make use of the known ages for fusion of epiphyseal growth plates for hedgehogs up to eighteen months old; this can be carried out on dead or anaesthetised individuals. The number of annular rings on a stained section of hedgehog mandible may be used for age estimation but requires a dead hedgehog and careful preparation and interpretation. 

Age Estimation Techniques: 

  • A wide variety of techniques for hedgehog age estimation are described in the literature; each has its own advantages and limitations therefore it is advisable to use a combination of results from several techniques during age evaluation.(B228.9.w9)
  • Body weight is too variable a parameter for use in age estimation.(B254.24.w24)
  • No externally visible signs are useful as accurate indicators of age.(B260.7.w7)
  • Biometric data of bone length provides a useful growth parameter in all seasons which can be monitored in individuals but varies considerably between hedgehogs.(B228.9.w9)
  • Studies have used the degree of enamel wear in the dentition to allocate age-rankings within samples of adult hedgehogs.(B228.9.w9) However rates of dental attrition also vary with diet type.(B260.7.w7, B291.12.w12)
  • Estimation of hedgehog age using the timings of dental eruption is not thought to be accurate although teeth which are unerupted confirm that the individual is juvenile. (B228.9.w9)
  • Analysis of the dry weight of hedgehog lenses from fresh post mortem material has been performed as a technique for hedgehog age estimation since lens weight increases throughout life. However this method is not though to be widely applicable because of the need for fresh and dead material.(B228.9.w9)
  • Alteration of calcium metabolism during hibernation results in reduced periosteal bone deposition; this can be seen as growth rings on a stained cut section of the hedgehog mandible. The number of annular rings can be used to estimate the age.(J46.161.w1, B228.9.w9, B254.24.w24, B291.12.w12) A transverse section at the level of the last molar is typically examined. Multiple studies have used this technique with success for age estimation although it is restricted to dead animals and requires specialist histological processing techniques. Confusion with analysis can arise since other physiological processes (e.g. pregnancy, illness) can create accessory growth lines.(J46.161.w1, B228.9.w9)
  • Radiographic studies have documented the pattern and age at which fusion of the epiphyseal growth plates in the hedgehog forelimb occurs. X-ray studies of dead or anaesthetised hedgehogs permits assessment of the stage of epiphyseal fusion allowing relative age determination up to an age of about eighteen months.(J46.164.w1, B228.9.w9)

(B142, B144, B147, B228.6.w6, B228.9.w9, B254.16.w16, B254.22.w22, B254.24.w24, B255.6.w6, B258.w7, B260.7.w7, B261, B262.8.w8, B262.10.w10, B291.12.w12, B341.3.w3, J46.161.w1, J46.164.w1, J46.220.w1, J180.26.w2)

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Authors & Referees

Authors Becki Lawson (V.w26); Debra Bourne (V.w5)
Referee Suzanne I. Boardman (V.w6); Nigel Reeve (V.w57)

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