Secrets of whales' long-distance songs unveiled , China daily 3-23-05

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Secrets of whales' long-distance songs unveiled ,

China daily 3-23-05

Wed, 23 Mar 2005 18:43:35 -0800

 

Secrets of whales' long-distance songs unveiled

 

www.chinaview.cn 2005-03-23 10:48:09

 

BEIJING, March. 23 -- Long ago scientists

discovered whales could

sing.

They can utter different sounds to express anger,

surprise and sadness

with

the changes of environments and their physical

conditions.

 

 

 

Long ago scientists discovered whales could sing. They

can utter

different

sounds to express anger, surprise and sadness with the

changes of

environments and their physical conditions.

It was also discovered that whales in the North

Atlantic Ocean seem

to

be moving together and coherently, even when they were

far away from

one

another.

 

Why do whales move in such a way? What is

impelling them forward?

How do

they communicate with each other, seemingly over

thousands of miles of

ocean?

 

For nearly nine years, Christopher Clark, a

researcher from Cornell

University of the United States, has been trying to

answer these

questions

by listening to whale songs and calls in the North

Atlantic using the

navy's

antisubmarine listening system. The underwater

microphones of SOSUS

(Sound

Surveillance System) can track singing blue whales,

fin whales,

humpback

whales and minke whales.

 

A world linked by songs

 

There is a time delay in the water, and the

response time for

whales'

communications is different from the time of human

beings. Sounds are

transmitted in the water at a speed of 1,450 meters

per second. This is

four

times faster than the transmission speed in the air.

As a result, when

whales communicate via songs, the responses come much

quicker.

 

Because humans still know so litte about whale

communications,

Clark and

his team decided to observe whale patterns of

association and

coordination.

 

Although the whales are spaced far apart, the

SOSUS system provided

a

wealth of new data. Through weeklong soundings, Clark

obtained

thousands of

acoustical tracks of singing whales from different

species throughout

the

year.

 

" We now have evidence that they are communicating

with each other

over

thousands of miles of ocean. Singing is part of their

social system and

community, " Clark said.

 

Excellent singers by birth

 

Whale songs have a much bigger wavelength than

human songs. The

songs

are very pleasant to the ears of whales born as bel

canto singers.

 

Scientists have also discovered that whales sing

new songs each

year.

New syllables appear constantly to replace old ones

and the new

syllables

soon spread worldwide. By using the tracking system,

scientists have

found

that a whale in Hawaii sings a similar song to a whale

in Bermuda. They

also

found that when a horde of whales return to their

original territory

after

long-distance trips, they first sing old songs of the

previous year and

then

new songs.

 

Information transfer via songs

 

Why do whales sing? Scientists think that they

sing to locate their

positions and to transfer information.

 

Whales will aim directly at a seamount that is 300

miles away, then

once

they reach it, change course and head to a new

feature. It is as if

they are

slaloming from one geographic feature to the next. It

means they must

have

acoustic memories much like our visual memories.

 

Whales communicate with each other via songs. To

avoid sending

information to their enemies, they use a unique

low-frequency, which

can

only be heard by allies.

 

It is still unclear why whales make long-distance

movements. What

is

influencing their movement and distribution? What are

the ocean

features

whales are honing in on?

 

Threats on whales' habitat

 

Just as researchers gain new ways of understanding

the linkages

between

whales and oceanographic features, what they hear is

the rising tide of

noise from an increasingly urbanizing marine

environment — the

collective

noises from shipping traffic, oil and gas exploration

and production,

and

recreational traffic. And every decade the amount of

noise is doubling.

 

" Many whales have very traditional feeding grounds

and their

migratory

routes occur along shallow coastlines, which are now

some of the

noisiest,

most heavily impacted habitats, " Clark explains. But

often it is along

these

routes that the male songs are sent long distance to

prospective

females,

who might not receive the message through the " ocean

smog. "

 

" If females can no longer hear the singing males,

they lose

breeding

opportunities and choices. The ocean area over which a

whale can

communicate

and listen today has shriveled down to a small

fraction of what it was

less

than a century ago, " said Clark.

 

(Source: Shenzhen Daily)