Bottlenose dolphins communicate mainly by means of sounds
and are almost always constantly vocal. These sounds includes
high-pitched whistles or squeals and short, pulse-type or
squawks eminating from their blowholes, with an average of
300 sounds per pulse. But they also use breaching (jumping
and falling back into the water with a loud splash) and pectoral
fin (or flipper) and tail (or fluke) slaps (hitting the flipper
or fluke on the water surface). Body posturing and jaw popping
also have a role in communication.
Bottlenose dolphins identify themselves with a signature
whistle. A mother dolphin may whistle to her calf almost continuously
for several days after giving birth. This acoustic imprinting
helps the calf learn to identify its mother. Dolphins regulate
their sounds by shunting air throughout the air sacs beneath
the blowhole. Tissue structures in this area slap together
(much like a trumpet player's lips) to produce the clicks.
These sounds often extend into the ultrasound region.
Dolphins can get specific information about a target by altering
the rate and frequency of the clicks they produce. Although
the clicks are definitely used in echolocation, the other
sounds seem to be involved in certain forms of limited communication.
Both whistles and burst-pulse sounds often fall below 20 kHz.
Burst - pulse sounds seem to be related to a dolphin's emotional
state. For example, those sounds often associated with aggression
have a "squawking" or "barking" quality.
Dolphins might produce "squeaking" tones when engaging
in playful activities. "Chirping" sounds can sometimes
be heard during sexual interaction.