Group size varies. Polygamy seems to be the rule in both species of Globicephala. Adult males are often scarred, presumably from battles over control of a harem. Fighting involves biting, butting with the large head, and slapping with the tail. Social organization seems to be highly developed in Globicephala, and this factor sometimes works to the disadvantage of the animals.
Individuals harpooned by people usually rush forward in panic and can be driven toward the shore.
The rest of the group seems to respond to the movements and cries of the wounded animals and to follow them into shallow water, where all may be easily killed. The same tendency may be associated with mass stranding, an especially common occurrence in Globicephala. It is possible that if a leader's echolocation mechanism fails to function properly, because of pathology or unusual environmental conditions, it will guide the entire group onto the shore. The gestation period averages 452 days, and mean length of the single newborn is 140 cm. The young begin to take some solid food at 6-12 months, but lactation continues for at least 2 years.