Why is the Equator a natural barrier to baleen whales?

From: Erich Hoyt (EHoyt@compuserve.com)
Date: Mon Feb 11 2002 - 04:07:18 EST


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Message text written by Graham Clarke

"
Why is the Equator a natural barrier to baleen whales?

Regards,
Graham Clarke
gclarke@magna.com.au

"

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Dear Graham,

For several reasons:

Those baleen whale species that approach the Equator from the north to mate
and calve, if they were then to carry on south after the mating and calving
season in the northern winter, they would encounter the southern winter in
what was supposed to be their feeding season. Any baleen whale doing that
would not be able to feed very well.

Whales may also be no different from other animals that are genetically
"programmed" to return to certain areas. But in addition with whales there
is a lot of evidence that they have preferred feeding and calving areas and
go back to the same areas their mothers took them to...

However, the Equator is not an absolute barrier: through photo-ID,
researchers have shown that humpbacks in the Antarctic migrating along the
west coast of South America, do indeed cross the Equator and proceed up
along the coast of Colombia and even into offshore Panama waters for their
mating and calving grounds. They then return to the Antarctic (or
subantarctic) joining the other southern hemisphere humpback whales.

Sincerely,

Erich Hoyt



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