. Social structure.
1. Bottlenose dolphins live in groups called pods (Scott, Wells, and Irvine, 1990).

a. A pod is a coherent long-term social unit.

b. The size of a pod varies significantly with its composition. On the west coast of Florida, mean pod size is about seven animals (Scott, Wells, and Irvine, 1990).

c. In the wild, pod composition and structure are based largely on age, sex, and reproductive condition (Wells, 1991).

(1) Researchers on the eastern U.S. coast commonly sight mother-calf pairs and pods of mature females with their most recent offspring (Wells, 1991).

(2) Subadults typically occur in mixed-sex and single-sex groups (Wells, 1991).

(3) Adult males are often observed alone, or in pairs or occasional trios (Wells, 1991). Adult males commonly move between female groups in their range, and may pair up with females for brief periods. Adult males rarely associate with subadult males (Wells, 1991; Herman, 1980).

2. In general, size of pods tend to increase with water depth and openness of habitat. This may be correlated with foraging strategies and protection (Shane, et al., 1986).

3. Several pods may join temporarily (for several minutes or hours) to form larger groups called herds or aggregations. Up to several hundred animals have been observed traveling in one herd (Shane, et al., 1986).

4. Researchers have identified certain factors that tend to cause a pod to either draw together or to disperse somewhat (Herman, 1980).

a. Factors that tend toward cohesion include protection, fright, and familial associations.

b. Factors that tend toward dispersion include alertness, aggression, and feeding.

5. There may be a social hierarchy within a group of bottlenose dolphins.


B. Social behavior.
1. Dolphins in a pod appear to establish strong social bonds. Behavioral studies suggest that certain animals prefer association with each other and recognize each other after periods of separation. Field observations suggest that mother-calf bonds are long-lasting.

a. Mother-calf bonds are long-lasting; a calf typically stays with its mother three to six years or more (Wells, 1991).

b. Adult male pair bonds are strong and long-lasting. Male pairs often engage in a number of cooperative behaviors (Wells, 1991).

2. Bottlenose dolphins establish and maintain dominance by biting, chasing, jaw- clapping, and smacking their tails on the water (Shane, et al., 1986; Herman, 1980).

3. Dolphins often show aggression by scratching one another with their teeth, leaving superficial lacerations that soon heal (Shane, et al., 1986). Traces of light parallel stripes remain on the skin of the dolphin. These marks have been seen in virtually all species of dolphins. Dolphins also show aggression by emitting bubble clouds from their blowholes.

4. During courtship, dolphins engage in head-butting and tooth-scratching (Shane, et al., 1986).

5. Bottlenose dolphins often hunt together. See Methods of collecting food.



Dolphin courtship behavior includes twisting, nuzzling, and tooth-scratching.

C. Daily activity cycles.
1 . Observations indicate that dolphins undergo daily cycles of activity.

2. Bottlenose dolphins are active to some degree both day and night (Shane, et al., 1986).

3. Social behavior comprises a major portion of bottlenose dolphins'daily activities (Shane, et al., 1986).

4. Feeding usually peaks in the early morning and late afternoon (Shane, et al., 1986).


D. Individual behavior.
1 . Dolphins frequently ride on the bow waves or the stern wakes of boats. This is probably adapted from the natural behavior of riding ocean swells, the wakes of large whales, or a mother dolphin's "slip stream" (hydrodynamic wake) (Shane, et al., 1986).

2. Dolphins have been seen jumping as high as 4.9 m (1 6 ft.) from the surface of the water and landing on their backs or sides, in a behavior called a breach.

3. Both young and old dolphins chase one another, carry objects around, toss seaweed to one another, and use objects to solicit interaction. Such activity may be practice for catching food.



In a common behavior called a breach, a bottlenose dolphin jumps out of the water and lands on its side.






E. Protection and care.
1 . Large adult males often roam the periphery of a pod, and may afford some protection against predators (Herman, 1980).

2. Researchers have observed scouting behavior in bottlenose dolphins. An individual may investigate novel objects or unfamiliar territories and "report" back to the pod (Herman, 1980).

3. Bottlenose dolphins may aid ill or injured pod mates. They may stand by and vocalize, or they may physically support the animal at the surface so it can breathe.




F. Interaction with other species.
1 . Bottlenose dolphins have been seen in groups of toothed whales such as pilot whales, spinner dolphins, spotted dolphins, and rough-toothed dolphins.

2. Bottlenose dolphins have been seen riding the pressure waves of gray whales, humpback whales, and right whales (Shane, et al., 1986). They often force Pacific white-sided dolphins away from prime spots in the waves (Herman, 1980).

3. Dolphins respond to sharks with tolerance, avoidance, and aggression. Tiger sharks elicit the strongest responses from dolphins (Shane, et al., 1986). Researchers have observed dolphins attacking, and sometimes killing, sharks in the wild (Herman, 1980).

4. Some individuals in the wild regularly solicit attention, such as touching and feeding, from humans (Shane, et al., 1986).