Killer whales extensively
rely on sound for orientation, prey detection, and communication.
Different types of sounds fulfill different functions for killer whales.
Echolocation clicks, for example, are used for orientation and prey
detection. Whistles are high-frequency sounds typically used by killer
whales in social contexts, and pulsed calls are communicative sounds
thought to play a role in the coordination of behaviours and maintenance
of group cohesion.
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| Pulsed calls can be categorized into
highly stereotyped call types. Different social groups within the
same population have group-specific repertoires of different call
types. As a result, resident killer whales in British Columbia and
Alaska exhibit an intricate system of vocal dialects. The structure
of these call types evolves slowly over time and is thought to be
learned.Transient forms of killer whales, unlike their resident counterpart,
rarely vocalize. They emit significantly fewer echolocation clicks
and communicative calls than residents. Transients presumably vocalize
less to avoid warning their prey. Indeed, marine mammals have excellent
underwater hearing and typically escape at the sound of a transient’s
underwater calls. |
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Estimating the abundance of killer
whales using the traditional ship survey method is costly, time consuming
and logistically challenging. In many areas the effectiveness of ship
surveys is further limited by impeding weather and sea conditions.
By comparison, acoustically monitoring the movement of killer whales
using remote hydrophones presents a relatively cheap and effective
alternative. In addition, because calls are specific to different
populations and social groups, the identity of the calling whale
can be identified by vocal monitoring.
Vocal monitoring can also provide information on predation rates
in areas of marine mammal abundance given that transient killer whales
usually become vocal after a marine mammal kill.
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with Sound
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