Notes
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BREEDING
SEASON:
- Mating February to June, litters March-October (B148)
- Iberian Peninsula: Mating occurs from autumn through the spring,
sometimes lasting longer. (B147)
- 90% of adult females pregnant Jan-June England, February-July Central Europe, with
pregnancy rare outside this time: reversed for introduced Southern Hemisphere populations
(B147)
- Breeding February to August/September in northern Europe. (B52,
B285.w5c)
- Breeding season mainly January to August (B142)
- In Mediterranean climates, winter breeding usually occurs, finishing
in late spring, whereas in more temperate areas breeding usually starts
early in the spring and carries on through to mid-summer. (B605.7.w7)
- Mating season varies depending upon the region, for example:
- Western Wales, UK: January to June.
- Netherlands: February to June.
- Germany: February to September.
- Western Australia, Australia: March/April to October.
- New Zealand: June to November.
- Sub Antarctic: July to May.
- New South Wales, Australia: Year-round.
(B287)
"The longest breeding seasons recorded are in warm
temperate New Zealand, with a well-distributed rainfall, where more than
50% of the adult females may be pregnant for nine months of the
year." (B605.7.w7) -
In the introduced populations in the Southern Hemisphere, the
breeding season spans the opposite half of the year to their northern
counterparts. (B147)
-
"In general, in its introduced range, breeding begins and
ends earlier in the year the lower the latitude." (B605.7.w7)
-
"From January to June in England and from February to July in
central Europe 90 percent of all adult females are pregnant; there are
only occasional pregnancies in other months." (B147)
- Captive individuals of this species in Australia were reported to
reproduce between June and December. (B287)
- "The European rabbit is notoriously prolific. It is liable to
breed opportunistically at any season..." (B605.7.w7)
- "The length of the season, and hence the number of litters
produced each year (at a rate of about one per month), depend on
the length of the growing season of the herbage on which it feeds."
(B605.7.w7)
- At higher latitudes, breeding only lasts about four months, whereas in
areas such as temperate New Zealand, breeding may last for up to nine
months. (B605.7.w7)
- In France, it has been reported that ovaries are large during the
spring, and small in the summer and autumn. (B287)
- In southern Sweden, uterine mass was reported to peak in May and June,
and be low in December. (B287)
- Opportunistic breeding often occurs in areas which experience
long-lasting droughts followed by occasional heavy rain leading to
sudden vegetation growth, such as semi-arid parts of Australia.
- During shorter days from late summer to winter, ovarian
activity decreases. (B612.8.w8)
- Domestic rabbits
- In domestic rabbits, there is variable reduction in breeding outside
the normal spring and summer breeding season seen in wild Oryctolagus cuniculus - European rabbit.
(B550.16.w16)
- Most does show a period of anoestrus for 1 - 2 months; some
females and males are fertile year-round. (B550.16.w16)
- Does may not become sexually receptive when moulting, lactating or
in poor nutrition. (B550.16.w16)
OESTRUS / OVULATION:
General Information
Specific Oryctolagus cuniculus Information
- Rabbits have a period of receptivity
- There is no regular oestrus cycle but there is a period of
receptivity, in which the doe allows copulation about every seven days; (B142,
B605.7.w7) every 5 or 6
days. (B612.8.w8)
- Cycle reported to last seven days on average (range: 4.5-41.5 days;
sample size = 67 cycles, 34 females). (B287)
- Induced ovulators. (B142,
B612.8.w8)
- There is a post-partum oestrus within a few hours of parturition; (B147,
B605.7.w7)
between 10 and 13 hours post-coitus. (B612.8.w8)
- Ovulation occurs 10 -13 hours after the stimulus of
mating. Contact with other female rabbits can also cause
ovulation. (B550.16.w16)
- Some females fail to ovulate following mating. (B550.16.w16)
- Re-mating may occur during pregnancy or pseudopregnancy. A second
mating within 2 - 3 days of the first mating can cause further
ovulation and fertilisation in a pregnant rabbit, and pertilisation
may also occur from mating towards the end of pseudopregnancy. (B550.16.w16)
GESTATION / PREGNANCY:
- Gestation lasts between 28 and 37 days, with 30-32 days seeming to be
most frequent. (B287)
- Resorbtion of embryos is common (B147)
- Implant: 7 days. (B287)
- The time of year during which pregnant females are found varies
depending upon the region, for example:
- Southern Sweden: March/April to August.
- New Zealand: Year-round, with a peak from June to October.
- France: Peak during the spring.
- Northern Cambridgeshire, England, UK: No pregnant females found
between October and December.
- Captive populations known to breed between March and August.
(B287)
"From January to June in England and from February to July
in central Europe 90 percent of all adult females are pregnant; there
are only occasional pregnancies in other months." (B147) It has been reported that at least 60% of all pregnancies are not
completed; the embryos are resorbed by the female. (B147) Reports from Wales indicate that heavy losses and resorption of
embryos (either single embryos or whole litters) occasionally occurred
early on in the gestation period. (B605.7.w7) Variable incidence of pre-natal mortality. (B605.7.w7) Pre-natal mortality is now "...seen as adaptive in allowing
does either to terminate a pregnancy or to reduce the size of the litter
if conditions are unfavourable for lactation." (B605.7.w7) Smaller litters have longer gestation periods than larger litters.
(B612.8.w8) "If a litter has not kindled by day 32 there is a higher
risk of the kits being stillborn." (B612.8.w8) Fetal loss can occur due to external factors such as poor body
condition and nutrition, age and time of year. (B612.8.w8) - Pregnancy usually lasts 30- 33 days; it may be longer if the litter
size is small. (B550.16.w16,
J35.151.w2)
- Occasional gestations of 29 or 35 days are noted. (B550.16.w16)
- Gestation periods of up to 40 days, resulting in a single or two,
abnormally large, stillborn young, have been reported. (B550.16.w16,
J35.151.w2)
- "Embryonic mortality is very high in rabbits with only about
60 to 70% successful births." (B612.8.w8)
- "Rabbits are particularly prone to fetal loss at day 13, when
placentation changes from yolk sacs to hemochorial, and at 23 days when
the fetuses are susceptible to dislodgement by rough handling." (B612.8.w8)
Pseudopregnancy
Infertile mating or the presence of a male nearby can cause
pseudopregnancy. (B612.8.w8) Pseudopregnancy can last for 16 or 17 days. The dam will not be
able to conceive during this time. Hair plucking may occur after 18 to
22 days, in order to make a nest. (B612.8.w8) Progesterone secreted by the corpus luteum during pseudopregnancy
causes the uterus and mammary glands to grow. "This is most
pronounced in the first 10 days; by day 16 the organs will involute and
at day 18 the corpus luteum will be disintegrating." (B612.8.w8)
PARTURITION / BIRTH: In newly constructed den lined with
vegetation, well removed from main burrow of colony (B142).
- Females first give birth at about 4 months of age. (B287)
- Females reported to give birth at different times of the year,
depending upon the region:
- Oxfordshire, England, UK: February to July, with a peak between
April and June.
- Netherlands and southern Sweden: March to July, with a peak in
May.
- Germany: March to October.
- New South Wales, Australia: From mid-June to unknown.
(B287)
-
Young are born into den which has been lined with vegetation. This
den is located well away from the main burrow of the colony. (B147)
-
Young are born underground. (B605.7.w7)
-
Domestic rabbit information:
Neonatal / Development:
- Birth: furless, blind (eyes closed) and deaf.
- 10 days old: eyes open.
- 3 weeks: leave nest.
(B52, B144,
B147, B148)
- Newborns are naked. (B285.w5c,
B605.7.w7)
- Neonates maintain body temperature via the activity of brown
fat; this is highest
in the first two weeks. (B612.8.w8)
- Born blind and helpless. (B605.7.w7)
- "The young are altricial with sealed eyelids and ear
canals." (B612.8.w8)
- Newborns weigh between 30 and 45 g. (B287);
weigh between 40 and 50 g. (B147,
B612.8.w8)
- Neonates usually weight between 40 and 45 g. (B285.w5c)
- Embryos weighed at 30 and 31 days gestation have been known to weigh
more than 45 g. (B287)
- Newborn females are reported to have an average weight of 35.23 g (se
= 1.140; Sample size = 40), with newborn males being slightly heavier
on average at 36.99 g (se = 0.0833, Sample size = 55). (B287)
- Eyes open at about ten days of age. (B285.w5c)
- Weaning mass: Reported to be between 175 and 221 g. (B287)
- Weaned at: 22-31 days. (B287);
about 20-21 days. (B605.7.w7); about 4 weeks of age. (B147); about 21 days. (B285.w5b)
- Young emerge from the den at about 21 days of age. (B287,
B605.7.w7)
- Eat solid food from about 21 days. (B287)
- Young are independent between 25 and 28 days. (B287)
- Due to the fact that neonates are hairless and the doe shows little
maternal behaviour, neonates are at high risk of hypothermia. (B612.8.w8)
See: Chilling - Hypothermia
- Passive immunity is acquired before birth. (B612.8.w8)
LITTER SIZE:
- One to nine, maximum 14 (144); 1-9 average 5-6 (B147), 5-6, occasionally to 12 (B52,
B285.w5c); 4-12 (B148); usually 3-7 (B142);
3-9 with average of 4-6 mid-season, and 3-4 during off-peak periods. (B605.7.w7)
- Between one and fourteen young per litter, though between four and
seven young appears to be most frequent. (B287)
- Peaks in litter size occur in the spring when pasture production is at
its maximum. (B605.7.w7)
- Seasonal and regional variation in litter size does occur, but it is
not as pronounced as in the length of the breeding season. (B605.7.w7)
- Domestic rabbit:
- Litters of 1 - 22 kits may occur, although the average is eight. (B550.16.w16)
- The first litter generally contains fewer kits than does the second
litter. (B550.16.w16)
- Breeds vary in whether litter size stays constant, increases or
decreases, and at what age it starts to decrease. (B550.16.w16)
TIME BETWEEN LITTERS / LITTERS PER YEAR:
General Information
- The inter-birth interval in lagomorphs is reduced by the phenomenon
of induced ovulation,
and post-partum oestrus, which allows females to conceive immediately
after she has given birth. (B285.w5a)
- A female can produce up to three or four litters per year. (B430.w2)
Specific Oryctolagus cuniculus Information
- Minimum interval about 30 days (B142); 3-5 litters/year (B148).
- Minimum interbirth interval is 29 days. (B287)
- Females produce between one and seven litters per year, though four or
five appears to be most frequent. (B287)
- Usually three to five litters per year. (B285.w5c)
- Five to seven litters per year. (B147)
- Females produce between about 15 and 45 young per year, depending on
the climate. The most productive areas appear to be improved pasture in
New Zealand. (B605.7.w7)
- Females can produce more than 30 young per year. (B147)
- "At least in northern regions, however, environmental
conditions, population pressures, and social factors seem to stimulate
controls that restrict the average annual production per female to only
10-12 young." (B147)
- "...annual reproductive rate of female rabbits depends
primarily on the length of the breeding season." (B605.7.w7)
- Domestic rabbits:
- "The reproductive capacity of rabbits is potentially up to
60 young per year as the doe has a post partum estrus within 24 hours
of kindling." (B612.8.w8)
- A doe can be bred while lactating if (a) she is mated on the same
day as parturition; or (b) she has only one or two young suckling her.
Otherwise, she can be bred again when the young are six to eight weeks
old, or earlier (three to four weeks) if the young are weaned onto
creep feed at that age. (B550.16.w16)
LACTATION / MILK PRODUCTION:
General Information
- Leporids only release milk once in every 24 hour period. (B285.w5b)
- Leporid milk has a very high fat and protein content, and as such is
highly nutritious. Although the lactation period is brief, the milk is
pumped into the young at a high speed.(B285.w5b)
- The lactation period has a duration of between 17 and 23 days. (B285.w5b)
Specific Oryctolagus cuniculus Information
- Weaning 4 weeks (B147), about 21-25 days (B142);
between 22 and 25 days. (B287)
- Milk composition: energy 2.06 Kcal/mL. Solids
31.2%, of which fat 49%, protein 32%, carbohydrates 6%, ash 6%. (P19.1.w5)
Domestic rabbits:
- Rabbit milk has an unusually low lactose content, and very
high fat and protein content:
- Protein: 13%
- Fat: 9%
- Lactose: 1%
- Minerals: 2.3%
(B612.8.w8)
- A gland near the nipple produces a pheromone which stimulates
suckling. (B612.8.w8)
- Consumption of both water and caecotrophs increases ten-fold
during lactation. (B612.8.w8)
- In high-producing does, milk can be produced before parturition
(kindling). (B550.16.w16)
- Usually, milk let-down occurs after kindling. (B550.16.w16)
- If milk let-down is delayed it may be stimulated with an injection
of prolactin. (B550.16.w16)
- On average, a doe produces 160 - 200 gm milk per day in her first
lactation and 170 - 220 gm per day in subsequent lactations. (B550.16.w16)
- Milk contains 15% protein, 10% fat, only 2% carbohydrates and 2 -
2.5% minerals. (B550.16.w16)
- Milk production reaches a maximum at two weeks, remains high to
three weeks, then decreases in the fourth week, but continues for up
to six to eight weeks, depending on various factors: diet, parity,
genetic factors and the number of young suckling. (B550.16.w16)
SEXUAL MATURITY:
- 5 - 8 weeks (B144).
- As early as 3.5 months (830 g body weight), but only those from early litters breed in
birth year. (B142)
- 3 - 5 months (B52).
- Both sexes become fertile at three or four months of age. (B605.7.w7)
- Variable results from different studies: (B287)
- Females first mate at about 6 months of age.
- Females first give birth at about 4 months of age.
- Females reach sexual maturity between 120 and 150 days.
- Spermatogenesis occurs at about 7 months of age.
- Males reach sexual maturity at about nine months.
- Both males and females are thought to start mating at four months of
age. (
- Males and females are thought to reach sexual maturity between five
and eight months of age.
(B287)
- In southern Spain, the majority of females first become pregnant at
three or four months of age. However, "...full reproductive
potential in wild populations is seldom attained before the second
calendar year." (B147)
- In New Zealand, females between nine and twelve months of age
reproduce at the maximum rate. (B605.7.w7)
- Domestic rabbits:
- Sexual maturity varies between breeds: it is reached at 4 - 4.5 months in small breeds, and
between 4.5 and 5 months in larger breeds. (B612.8.w8)
- While small "Polish" rabbits may be bred at four months
and medium-weight New Zealand and Chinchilla rabbits at four to seven
months, heavy Flemish rabbits may be bred only at nine to 12 months. (B550.16.w16)
- Females of domesticated varieties can become pregnant at just three
months of age. (B147)
- Some mobile protozoa may be present in ejaculate of bucks just four
months old; adult levels of spermatozoa are reached at seven to eight
months. (B550.16.w16)
MALE SEASONAL VARIATION:
- Spermatogenesis reported to occur year-round in southwestern
Australia, and in northern Cambridgeshire, England. (B287)
- Testes: The time of year during which the testes are large or
small varies depending on the region:
- Southern Sweden: Large between March and August, small in
October.
- The accessory glands are at their largest in May and June. (B287)
- Northern Cambridgeshire, England: Large between April and May.
Low in October and November.
- New Zealand: Large in September, small in January.
- France: Large in the spring, small in the summer.
(B287)
LONGEVITY / MORTALITY:
General Information
- Rabbits and hares in the wild live for less than a year on average;
a maximum age of 12 years has been recorded in a couple of species. (B285.w5b)
Specific Oryctolagus cuniculus Information
- Usual 1.5 years, maximum 10 years (B144).
- Rarely more than 9 years (B147).
- 10 years (B52,
B285.w5c).
- 5-8 years (B148).
- First year mortality may be 95% (B142).
- Does not usually live longer than nine years. (B147)
- Mortality rates are thought to be higher in New Zealand and Spain than
in Australia. (B605.7.w7)
- In Australia, it is thought that more than 80% of young are predated
upon. (B605.7.w7)
- For adults of more than six months of age, annual mortality rates are
usually greater than 60%. However, mortality rates may be as low as 25%
in some low-density populations found in New Zealand. (B605.7.w7)
- In the wild, this species is thought to live up to about seven or
eight years. (B605.7.w7)
- This species can reproduce until approximately six years of age. (B147)
- Domestic rabbits:
- Average life span is between 7 and 10 years. (B612.8.w8)
- Some females continue reproducing well to five or six years old. (B550.16.w16)
- Bucks generally maintain reproductive activity for up to 5 - 6 years.
(B550.16.w16)
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