Look, who is calling?
Four different types of killer whales live in the Southern Ocean. They are known to differ in feeding ecology and appearance. However, little is known about the distribution and behaviour of these different killer whale ecotypes. To answer these questions, scientists monitor the whales’ communication with specific underwater sound recorders. However, so far nobody knew, which calls the different ecotypes are using.
Now marine biologists Ilse Van Opzeeland and Elena Schall from the Alfred Wegener Institute managed for the first time to record killer whale calls and identify which ecotype produced them. Those recordings were made in the Weddell Sea, where the scientists are running the acoustic underwater observatory PALAOA in vicinity to the German research station Neumayer III. While the animals were hunting in the bay, overwinterers from Neumayer Station III drove to the edge of the ice shelf and took photos of the whales. Later on the marine biologists could identify the whales as source of the recorded sounds.
Ecotype C killer whales are the smallest killer whale form known worldwide. During their four hours long conversation they used more that 2000 clicks, whistles and pulsed calls. The latter scientists could classify into 26 discrete call types. Their distinct characteristics could serve as acoustic marker for sound-based differentiation of killer whale ecotypes in the Southern Ocean and help scientists to discover more about the different orca ecotypes that populate this remote area.
These research results have been published yesterday in the scientific journal Aquatic Mammals. The paper’s title is: Elena Schall, Ilse Van Opzeeland: Calls produced by ecotype C killer whales (orcinuc orca) off the Eckström Iceshelf, Antarctica. Aquatic Mamals 2017, 43(2) 117-126, DOI: 10.1578/AM.43.1.2017.117
This video shows what the killer whales from Atka Bay sound like: