Irrawaddy Dolphins' Behavior

Irrawaddy dolphins communicate with clicks, creaks and buzzes at a dominant frequency of about 60 kilohertz which is thought to be used for echolocation. Bony fish and fish eggs, cephalopods, and crustaceans are taken as food. Observations of captive animals indicate that food may be taken into the mouth by suction. Irrawaddy Dolphins sometimes spit streams of water, sometimes while spyhopping, during feeding, apparently to expel water ingested during fish capture or possibly to herd fish. Some Irrawaddy Dolphins kept in captivity have been trained to do spyhopping on command. The Irrawaddy Dolphin is a slow swimmer, but swimming speed of 20–25 km/hour was reported when dolphins were being chased in a boat.
It surfaces in a rolling fashion and lifts its tail fluke clear of the water only for a deep dive. Deep dive times range from 70–150 seconds to 12min. When 277 group dives were timed (time of dis-appearance of last dolphin in group to emergence of first dolphinin the group) in Laos, mean duration was 115.3 s with a range of 19 s to 7.18 min.^[They make only occasional low leaps and never bow-ride. Groups of fewer than 6 individuals are most common, but sometimes up to 15 dolphins are seen together.

Interspecific competition has been observed when Orcaella was forced inshore and excluded by more specialised dolphins. It is also reported that when captive Humpback Dolphins (Sonsa chinensis) and Irrawaddy Dolphins were held together, the Irrawaddy Dolphins were frequently chased and confined to a small portion of the tank by the dominant Humpbacks. In Chilika Lake, local fishers say that when Irrawaddy Dolphins and Bottlenose Dolphins meet in the outer channel, the former get frightened and are forced to return toward the lake.