Carnivores have polygynous, polygynandrous, and monogamous mating systems. Southern elephant seals (Mirounga leonina) demonstrate extreme polygyny, wherein males fight for exclusive access to harems of females. Gray wolves (Canis lupus), on the other hand, are monogamous cooperative breeders; the dominant male and female of each pack breed and all members of the pack help raise their offspring. Solitary carnivores, such as bears, mustelids, and cats, are often polygynandrous, with males and females each having multiple partners during the breeding season.
Mating System: monogamous ; polygynous ; polygynandrous (promiscuous) ; cooperative breeder
Carnivores breed either aseasonally or seasonally; those in cold climates usually mate in winter and spring and give birth to their young during spring and summer. Females may be polyestrus or monoestrus; in some species, ovulation is induced by the act of mating. Carnivores may have two or three litters per year (as with least weasels), but most carnivore females have just one litter every one to two years. Delayed implantation, wherein the blastocyst lies quiescent for several months before implanting in the uterine lining, is common in some carnivore families (such as mustelids). After implantation, gestation periods range from five weeks in least weasels to 15 months in walruses. Typical true gestation periods last two to four months. Litter sizes range from 1 to 16, and are commonly 3 to 5. Females nurse their young for up to two years, and the young take up to seven years to reach sexual maturity.
Key Reproductive Features: iteroparous ; seasonal breeding ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); induced ovulation ; viviparous ; delayed implantation
Female carnivores nurture their young inside their bodies for up to 15 months and provide their young with milk after birth. The length of nursing varies considerably among carnivores. Some phocids only nurse their young for a couple of weeks, whereas walruses nurse their young for up to two years. The duration of lactation in terrestrial carnivores falls between these two extremes. Carnivore young range from highly precocial, harbor seal (Phoca vitulina) pups are able to swim a few minutes after birth, to altricial, as in bears. Female carnivores usually bear the sole responsiblity for nurturing and protecting their offspring, but male parental care is not uncommon, especially among canids. Carnivores that live in groups and breed communally may all share in the task of raising each others' offspring. In some social species, like spotted hyenas (Crocuta crocuta), the mother's position in the dominance hierarchy determines the position of her offspring. The young of spotted hyenas, wolverines, sea otters, bears, and large felids stay with their mothers for up to two years even though they are weaned well before this time; they depend on their mothers for food until they become proficient at hunting for themselves. In carnivores that form close-knit social groups, bonds between mother and offspring may extend well beyond the period of offspring dependency.
Parental Investment: altricial ; precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female); post-independence association with parents; extended period of juvenile learning; inherits maternal/paternal territory; maternal position in the dominance hierarchy affects status of young
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