Bottlenose Dolphins
(Tursiops truncatus)

Tursiops species is incredibly social, with varying levels of interaction occurring. One clue into the sociability of bottlenose dolphins is that of their versatile vocal repertoire. Dolphins exhibit a range of sounds, from clicks, buzzes, whistles, yelps and barks, to echolocation sounds beyond our range of hearing. It is thought that audible sounds are used to signal emotional state and echolocation is used to locate things such as prey and other dolphins (Gaskin, 1982). Whistles also serve as a means of identification among dolphins, as each individual appears to have a unique whistle tone and pattern. Yelps are generally associated with sexual signalling by males. Females can gauge age and experience by the type and complexity of yelp emitted (Gaskin, 1982).

Dominance interactions
Bottlenose dolphins do not display a dominance hierarchy within a group or herd, but dominance interactions are seen. Dominance is based entirely on age and size. Older dolphins are more experienced and familiar with where to find food, mates, and nursing grounds, so they lead the herd through its range (Samuels and Gifford, 1997). Some research, suggests that there is a matriarchal structure in the herd, which becomes clearest during mating seasons (Gaskin, 1982). This hypothesis is based on the facts that the mother-offspring bond is the core unit or group in a herd, and that alloparenting occurs among dolphin females (Gaskin, 1982). Alloparenting becomes especially important during mating seasons, to ensure that while one female is off in the breeding cohort, her calf, which is generally still dependent for a couple years after she becomes sexually active again, is protected and looked after. A matriarchy is also evidenced when the oldest dolphin is at the head of a school during travel or feeding activities.

Cooperative hunting
While solitary hunting occurs, dolphin herds and even pods are often seen herding schools of fish, and hunting together. This cooperative hunting increases the success of catching fast moving, schooling prey, because many dolphins act together to herd and trap the prey.

Gaskin (1982) does not agree with the popular argument for the existence of cooperative hunting. He is of the opinion that the "herding" of fish that is observed in dolphins, is simply a convergence of several dolphins on one school of fish, each one hunting its own individual prey. He argues this because of the general solitariness of dolphins and because of the implications for dolphins having a conscious "purpose" were they to hunt cooperatively. While some dolphins do hunt alone, cooperative hunting has been shown to increase hunting efficiency in other mammals (e.g. wild dog) so it is very likely to be an evolutionary adaptation.

Allomaternal care
Females who are not mothers often escort calves, while the mother is foraging, socialising or resting. This allomaternal behaviour is associated with training for maternity (Mann and Smuts, 1998). See Parent-Offspring care for more detailed information.

Male-female
Males and females have very little interaction after juvenile males leave their natal herds. Females remain in a herd, while males either become solitary or form cohorts with 1 or 2 other males. These cohorts are advantageous in hunting and for herding females whit which to mate. Interactions of adult male and females are restricted to consortships for mating. See Mating Systems for more detail.