Bottlenose dolphins live in groups called pods. A pod is a
coherent long-term social unit. The size of a pod varies significantly
with its composition. On the west coast of Florida, mean pod
size is aboout seven animals. In the wild, pod composition
and structure are based largely on age, sex, and reproductive
condition. In general, size of pods tend to increase with
water depth and openness of habitat. This may correlated with
foraging strategies and protection.
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. There are certain factors that tend to cause
a pod to either draw together or to disperse somewhat. Factors
that tend toward cohesion include protection, fright, and
familial associations. Factors that tend toward dispersion
include alertness, aggression, and feeding.
Bottlenose dolphin's social behavior and organization are
one of the most complex and advanced in the animal kingdom.
There appears to be a dominant dolphin that leads the pod.
Dominance is established among males in a series of behaviors
such as tail slapping.
Those bottlenose dolphins who are in a pod have established
strong social bonds. It appears that certain animals prefer
association with each other and recognize each other after
periods of separation. Mother-calf bonds are long-lasting;
a calf typically stays with its mother three to six years
or more. Adult male pair bonds are strong and long-lasting.
Male pairs often engage in a number of cooperative behaviors.
Bottlenose dolphins establish and maintain dominance by biting,
chasing, jaw-clapping, and smacking their tails on the water.
Dolphins often show aggression by scratching one another with
their teeth, leaving superficial lacerations that soon heal.
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.
During courtship, dolphins engage in head-butting and tooth-scratching.
Bottle-nose dolphins often hunt together. (see: Methods of
collecting food.) Dolphins have been observed frequently stroking
each other with their flippers, hence, indicating that they
require physical contact much like humans.