Recent studies show that the Kauai and Niihau Bottlenose populations are unique amongst the Hawaiian islands (Baird et al) as the Kauai and Niihau populations do not travel to the other islands. Additionally, genetic sampling shows that we have two distinctive groups, a near shore group and off shore group.
Bottlenose dolphins are grey, varying from dark grey at the top near the dorsal fin to very light grey and almost white at the underside. This makes them harder to see both from above and below when swimming. The elongated upper and lower jaws form what is called the rostrum and give the animals their name of bottlenose. The real nose, however, is the blowhole on top of the head. Their face shows a characteristic “smile”.
Bottlenose dolphins communicate with one another through squeaks, whistles, and body language. Examples of body language include leaping out of the water, snapping jaws, slapping tails on the surface of the water, and butting heads with one another. All of these gestures are a way for the dolphins to convey messages.
Adults range in length from 2 to 4 meters (6 to 13 feet) and in weight from 150 to 650 kg (330 to 1430 pounds) with males being slightly longer and considerably heavier than females on average. They are fast swimmers, reaching peak speeds of 18 knots per hour (21 mph). Their diet consists mainly of small fish, squid, octopus and the occasional crab.
Female bottlenose dolphins live for about 40 years; the more stressful life of the males apparently takes its toll, and they rarely live more than 30 years.