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.)
Tue Nov 29, 2011 4:20 pm