Behavior And Reproduction
Botos usually swim alone or occasionally with one or two other botos. They communicate with each other using a series of "clicks" that are above the range of human hearing. These communication sounds are not well understood. Botos kept in captivity have been aggressive toward each other, suggesting that in the wild they need to keep a certain distance between themselves and other botos. They are occasionally observed in larger groups when feeding.
Botos swim slowly, sometimes on their backs. They come to the surface to breathe every thirty to sixty seconds, but rarely leap out of the water or even show much of their body above the surface. They are, however, playful and curious. Botos have been seen playing with floating logs or turtles and have been known to come up to boats and rub against them.
Female botos give birth to a single calf after an eleven-month pregnancy beginning when they are three to five years old. After that, they have a single calf every two to five years. Most births occur between May and August, newborns being about 30 inches long (75 centimeters) and weighing about 15 pounds (7 kilograms). They nurse, feed on their mother's milk, for more than a year. Natural lifespan is estimated at about thirty years. Botos do not appear to migrate.