Sirenia
Reproduction

Despite being mostly solitary, sirenians congregate in groups while females are in estrus. These groups usually include one female with multiple males. Sirenians are K -selectors; despite their longevity, females give birth only a few times during their lives and invest considerable parental care in their young. Dugongs generally gather in groups of less than a dozen individuals for one to two days. Since they congregate in turbid waters, little is known about their reproductive behavior. The males are often seen with scars, and the tusks on dugongs grow in first for males, suggesting they are important in lekking. They have also been known to lunge at each other. The age when a female first gives birth is disputed, ranging anywhere from 6 to 17 years. The time between births is unclear, with estimates ranging from 2 to 7 years. In Sarasota, Florida, 53 females under observation produced at least 55 calves during a five-year period.

Manatees can reach sexual maturity as early as two to five years of age. Manatee gestation is around one year, and then they lactate for one to two years. West Indian manatees and African manatees can breed year-round, and a female will mate with multiple males. Amazonian manatees have a breeding season, usually mating when the river levels begin to rise, which varies from place to place.
keywords:frequency