Because manatees cannot survive very long in water below 68 degrees Fahrenheit, south Florida and some natural springs make to the Florida manatee's natural winter range. Manatees depend on seagrass and other aquatic vegetation for food. In the winter, they congregate around warm water springs and man-made sources of warm water such as power plant discharges. Manatees can live for several decades. Adult females give birth to a calf about once every three years.
Manatees have few natural predators.
The greatest natural threats are exposure to cold temperatures, hurricanes, and poisoning from red tide. No one knows exactly how many manatees there are now or how many there were at any time in history. Aerial surveys are done every year. However, these surveys are inexact because of changing weather conditions, water clarity, manatee behavior, and other factors. As a result, scientists are reluctant to base their evaluations of the manatee population on these surveys.