Myocastor coypus is polyestrus. The length of the estrus cycle is variable; intervals between cycles may range from 5 to 60 days. Nutrias are nonseasonal breeders. The gestation period is long, varying from 127 to 139 days. There is a post-partum estrus within 2 days of parturition. Mean litter size in general varies from three to six, although it may range from 1 to 13. Factors affecting reproductive potential of nutria are food type and availability, weather conditions, predators and disease.
Sexual maturity is attained when young are only 6 months old.
Gosling (1981), Gosling and Baker (1981), Woods et al. (1992).
Breeding interval: Nutrias may breed repeatedly throughout the year, the interval will depend on climate and nutritional status of the mother.
Breeding season: Breeding may occur throughout the year.
Range number of offspring: 3 to 12.
Average number of offspring: 5.75.
Range gestation period: 126 to 141 days.
Average weaning age: 54 days.
Average age at sexual or reproductive maturity (female): 6 months.
Average age at sexual or reproductive maturity (male): 6 months.
Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous
Average birth mass: 225 g.
Average number of offspring: 6.
Average age at sexual or reproductive maturity (male)
Sex: male: 152 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 152 days.
Females care exclusively for the young. Newborns are fully furred, and have their eyes open. They weigh approximately 225 grams each, and rapidly gain weight during the first 5 months. The lactation period extends for about 8 weeks.
Parental Investment: no parental involvement; precocial ; pre-fertilization (Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)