the culture of Orca Whales' voice

本文同时提供以下语言的翻译:中文

First of all, communication in whales is thought to have evolved before toothed whales and baleen whales diverged.Killer whales are relatively well studied among them.Researchers can determine the emotional color and purpose of orca sounds: maintaining individual bonds, moving in sync, and resolving aggression and sexual conflict.
So, these calls can be used in a variety of different behavioral environments, and this is a typical orca call.

Killer whales are found in all oceans, but are divided into many populations and ecological groups.Different populations exhibit great variation in feeding habits, behavior, morphology, and genetic inheritance.Studies have shown that the evolution of a population’s language has nothing to do with its location (in relation to the distance of another orca population) : so there is no such thing as having two regional dialects that are very close together, as in humans.
It is thought that orcas may have learned their communication skills early in life and preferentially received calls from animals with whom they often interact socially.Young whales in the wild spend most of their first year close to their mothers and gradually begin to interact more with their own and related female whales.
Current knowledge about orca acoustic communication comes mainly from populations in the North Pacific and northeast Atlantic, while relatively little is known about the structure and use of vocalations in other populations.In this article, we will review different aspects of orca acoustic communication to provide insight into the processes that lead to stereotypical call changes, which result in extreme diversity of groups and population repertoire.

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###The language of Orca Whales

Killer whales produce a wide variety of vocal signals, which can be divided into three categories: clicks, calls, and whistles.Like other toothed whales, killer whales perform echolocation by making clicking sounds, which allows them to navigate and locate underwater objects based on the acoustic properties of the echoes, such as time and frequency.Thus, echolocation clicks are not the primary communication signal, although individuals can still extract valuable information (such as foraging information) from other individuals’ echolocation click patterns.The function of calls and whistles is not well understood, but it is thought that their main function is to maintain group cohesion and coordinate social relationships.Most calls are rigid, but their structures are very diverse, ranging from simple low-frequency squeaks to complex polysyllabic high-pitched calls.The collection of modular calls forms different tracks, allowing different members to identify and track each distant member.

Examples:

Although killer whale calls are very diverse, they can be grouped into large categories that appear to have specific functions related to their structure.
For example, in killer whales in the North Pacific, calls with two overlapping independently modulated components (double calls, below) generally produce higher sound pressure intensity than monophones.
The high frequency component is more directional than the low frequency component, which may allow the intensity of the upper low frequency component in proportion to the direction recognized by the receiver and the direction the caller is moving.
These findings suggest that an approximate function of two-tone calls is remote coordinated motion.

In contrast, monophonic calls are heard more often in social Settings where groups are in close contact.
After a successful Marine mammal kill, transient animals in the North Pacific used mono calls only when communicating in their social groups, but made double calls when two distant groups communicated during a meeting.

Some calls seem to be used more frequently in certain behavioral contexts.
For example, variation and abnormal calls are used more often than rigid calls during social interactions among local orcas.

Researchers (Rehr,2011) have identified a specific class of variable calls characterized by rapid up and down frequency modulation and called “excited” calls.
The call has been found in all three ecotypes of killer whales in the North Pacific.
These calls seem to be used primarily in high-stimulation states.
This modulated pattern of calls was made by killer whales when they were exposed to navy sonar.
It is speculated that they may play a role in the aggressive behavior, as this is one of the most significant changes in the call structure in the aggressive behavior of captive orcas originating in Iceland:
The only environment-specific call reported so far is the so-called “herd call” by killer whales in Iceland and Shetland islands, which appears to be specifically used to manipulate herring into dense schools during feeding.

In individuals and groups of different populations and ecological types, the use of sound varies according to the type of activity and seems to be primarily related to the social environment and the type of prey being pursued.
Inhabitants of the Northeast Pacific (a fish diet) Orcas often make sounds in any state of activity (except at rest).
In contrast, the northeast Pacific transient (mammalian feeding) killer whales mostly call and whistle only after killing or when socializing, and remain mostly silent during other active states.