Dolphins reproduce by engaging in intercourse during the female's ovulation period. A female may mate with more than one male dolphin during her fertile time, and males may even travel together with one fertile female and take turns mating with her. Competition can get fierce among male dolphins during a female's estrus.
Dolphins mate throughout the year with an increase in the spring and fall seasons. A female dolphin will carry a baby, called a calf, anywhere from nine to 17 months depending on the type of dolphin specie. Dolphin calves will stay with the mother and nurse for up to 2 years and remain with the mother for anywhere from eight to nine years.