Re: birding-aus Re: an addendum on migration

To: Mark Chappell <>,
Subject: Re: birding-aus Re: an addendum on migration
From: David James <>
Date: Thu, 06 May 1999 08:54:15 +1000
As an aside, several baleen whales (not grey whales) fast on the wintering
grounds. there's little scraps of evidence for individuals of some species
feeding during migration but this doesn't really contribute much to their
annual food consumption. Humpbacks at least equal or out-distance grey
whales, travelling from Arctic Alaska to hawaii, arctic Canada to the
Caribbean, and from the Antarctic ice pack to tropical coasts of the
southern continents ocean.

Another salient point in the energetics of cetaceans (whales & dolphins) is
that they never stop swimming, because they have to come to or remain at
the surface to breathe. They don't sleep as humans and birds do, but go
into a sort of half shut-down while continuing to swim in a slow regular
pattern with a greater amount of their senses still operating. 

Its really comparing apples and oranges to speak of the relative metabolic
effiency of beasts as different as hummingbirds and blue whales.  

At 16:17 5/05/99 +1000, Mark Chappell wrote:
>*** In my last diatribe I forgot to mention that the longest mammal
>migration I know of is that of the gray whale, which goes between Mexico
>and the Arctic Ocean near Alaska (many thousands of kilometers).  But this
>isn't really comparable to nonstop bird migration, since the whales make
>the journey in months and are able to stop, rest, and eat on the way.  The
>movements of many southern hemisphere whale species between Antarctic
>waters and temperate/tropical oceans are comparable, 

David James
PO BOX 5225
Townsville Mail Centre,
Qld 4810, Australia

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