A CANADIAN scientist has found that killer whales ‘speak’ a number of
different ‘dialects’ and ‘languages’. Differences between the dialects can
be as small as those that distinguish regional dialects of the English language,
or as large as those between Japanese and English.
The finding puts the whales in an elite club among mammals, along with
humans, some primates and harbour seals. The sounds produced by other mammals
are determined genetically.
John Ford, curator of marine mammals at the Vancouver Public Aquarium,
has been studying the way killer whales communicate for a decade. He says
that killer whale dialects are made of the whistles and calls the animals
use when communicating underwater. They are quite distinct from the high-energy,
sonar-like ‘clicks’ that the whales emit when navigating by ‘echolocation’.
Killer whales are the largest member of the dolphin family. They probably
acquired their ‘killer’ reputation because they have been known to kill
and eat other dolphins and whales, in addition to their usual prey: sea
lions, seals, porpoises and fish. There is no evidence that they have ever
attacked humans.
Killer whales are found throughout the oceans of the world, from the
tropics to the north and south poles. However, the largest concentrations
are found off the coastal regions of cooler countries, such as Iceland and
Canada.
Ford has studied a population of approximately 350 killer whales which
live for the whole year off the coast of British Columbia and northern Washington
State. These whales form two separate communities that roam through adjacent
territories.
The ‘northern’ community, which consists of 16 family groups, or ‘pods’,
ranges from mid-Vancouver Island north to the southeast tip of Alaska. The
members of a smaller ‘southern’ community consisting of three pods wander
from the border of the northern community all the way south into Puget Sound
and Grays Harbour.
Most sounds produced by killer whales are within the range of human
hearing. For this reason, Ford has found it relatively easy to record their
communication. He dangles a hydrophone over the side of the boat. The sounds
are amplified electronically and recorded on a tape recorder.
Ford has been able to categorise the calls – the dialect – of each pod.
He has found that, typically, a pod makes 12 discrete calls. All members
of the pod can, and do, produce the full set of sounds. Ford says that the
system of calls is different, both quantitatively and qualitatively, from
other whales and dolphins.
Most calls are used only within a pod, but sometimes one or more are
common between pods. Ford has found that the dialects are passed from generation
to generation within each pod, and he speculates, therefore, that groups
which share calls probably descended from a common ancestor. The more calls
two pods have in common, the closer the family relationship.
This ‘phylogenetic’ link between dialect and pod has enabled Ford to
estimate how long it takes for a separate dialect to emerge. ‘The rate of
change appears to be very slow’, he says. ‘It (a dialect) must require centuries
to develop.’ The implication is that some dialects could be thousands of
years old.
Up until now, Ford has found little correlation between the behaviour
of killer whales and the calls they make. However, he has found that calls
are faster, higher in pitch, and more frequent when an animal is excited.
Ford believes that taken together the calls form an ‘elaborate code
of pod identity’ which enables whales to identify fellow members of their
pod. This is especially important, he thinks, when collections of pods,
known as ‘superpods’, swim together.
According to Ford, killer whale communication has no grammatical structure.
But he is impressed by its acoustic sophistication. ‘They seem to have a
very highly developed, efficient way of communicating that is something
we can only partly understand at this point,’ he says. ‘I think as time
goes on, we’ll get a much better appreciation of just how remarkably adapted
whales . . . are to their unique environment.’
Read more: https://www.newscientist.com/article/mg12517072-900-science-killer-whales-communicate-in-distinct-dialects/#ixzz675rul5tD
Explanation:
