WALES COMMUNICATION SYSTEM
The frequency of killer whale whistles ranges from about 0.5 to 40 kHz, with peak energy at 6 to 12 kHz. Studying northern resident killer whales, researchers found that the whales produced more whistles when they were close to other individuals and only sporadically emitted them when the whales were dispersed over larger areas.
Pulsed calls are the most common vocalization of killer whales.
Experts think these calls function in group recognition and coordination of behavior.
• Killer whales make these calls at frequencies of about 0.5 to 25 kHz, with peak energy at 1 to 6 kHz.
Calls that sound the same time after time are called stereotyped calls. All a killer whale’s stereotyped calls make up that whale’s repertoire.
The individuals of any particular pod share the same repertoire of calls, a vocalization system called a dialect.
Although scientists have noted that there is some type of structure to the calls, a dialect is not the same thing as a language.
• Analysis of killer whale call patterns has demonstrated substantial differences between the dialects of different pods.
Pods that associate with one another may share certain calls (“clans”).
° No two pods share the entire repertoire. Thus, each pod has its own unique dialect. In fact, the vocal repertoires of each pod remain distinct enough that scientists can identify pods by the sounds they make.
° Killer whales that are separated by great geographical distances have completely different dialects. An analysis of Icelandic and Norwegian killer whale pods revealed that the Icelandic population made 24 different calls and the Norwegian whales made 23 different calls, but the two populations did not share any of the same calls.
A calf is most likely to develop calls like those of its mother. Vocal development studies at SeaWorld have determined that a calf learns its repertoire of calls selectively from its mother, even when other killer whales may be present and vocalize more frequently than the mother.
A calf can vocalize within days of birth, but sound production is shaped with age. A calf’s first vocalizations are “screams”—loud, high-pitched calls that bear no resemblance to adult-type calls.
• At about two months, a calf produces its first pulsed calls with similarities to adult-type calls.
• Vocal behavior appears not to be genetically predetermined. Calves learn which calls to make and under what circumstances.
• From two to six months, a calf’s repertoire increases. Calves continue to learn calls until puberty.
6. Like many other animals, toothed whales may also communicate using a variety of postures and gestures. Some behaviors, such as head-butting and jaw-snapping, are usually assumed to communicate aggression. The purpose of other behaviors, including breaching and pec-slapping, is not clearly understood.
7. Bioacoustic studies can be an important means of tracking pod movements. If they provide a reliable index of genetic variability, they can also become a useful management tool.
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The term echolocation refers to an ability that odontocetes (and some other marine mammals and most bats) possess that enables them to locate and discriminate objects by projecting high-frequency sound waves and listening for echoes.
A whale echolocates by producing clicks and then receiving and interpreting the resulting echo.
The echolocating killer whale produces directional, broadband clicks in rapid succession, called a train. Each click lasts less than one millisecond. Killer whale echolocation clicks can be up to about 35 kHz, with their peak energy at about 12 to 25 kHz.
• The click trains pass through the melon (the rounded region of a killer whale’s forehead), which consists of lipids (fats). The melon acts as an acoustical lens to focus these sound waves into a beam, which is projected forward into water in front of the whale.
• The sound waves produced by a killer whale bounce off objects in the water, and their echoes return to the whale.
• Echoes are probably received and conducted through the lower jaw to the ear. See Senses.
3.An echolocating killer whale can determine the size, shape, speed, distance, direction, and even some of the internal structure of objects in the water.
whales echolocate by producing high frequency clicks that pass through the melon, then receiving and interpreting the resulting echo.