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The giant Haast's Eagle of New Zealand was an overgrown Little Eagle!!

To: "Graham Turner" <>, "Alan Gillanders" <>
Subject: The giant Haast's Eagle of New Zealand was an overgrown Little Eagle!!
From: "Chris Sanderson" <>
Date: Fri, 12 Sep 2008 16:12:54 +1000
Graham,

If it were Bergmann's rule at work in your magpie example, is Lancefield
colder or warmer than the Blue Mountains?  I would expect Bergmann's to be
applicable over altitudes as well as latitudes if it is truly related to
body mass/climate.  The theory goes that a smaller animal has a larger
surface area to volume ratio, so bleeds more heat per unit of weight into
the air than a larger animal with the same layers of protection.  This is
why tiny mammals have such high heart rates, to fuel an intense metabolic
reaction to keep them warm, and also why elephants have very slow
heartbeats.  Torpor and hibernation work outside of this (torpor in
hummingbirds is particularly amazing!), as they involve shutting off the
metabolic process, nearly stopping the heart, but somehow allowing the
organs and tissue to survive cooling down to ambient temperatures.

But as Graham points out, it is just a rule.  Very few things in biology
lack a counter-example to disprove them.  Evolution seems to be very good at
finding novel solutions.  I can't immediately think of any birds on
east-coast Australia that break Bergmann's rule, if I think of any I'll post
them.  I believe that our various fruit-doves conform to the rule?

Regards,
Chris

On Fri, Sep 12, 2008 at 3:44 PM, Graham Turner <>wrote:

> I remember head south to Lancefield in Victoria 6 or so years ago and being
> amazed at the size of magpies when compared to the ones I see around the
> Blue Mountains.  Seems to work for me. Maybe its not applicable to
> everything, but it is a 'rule' no a 'law.
>
> Cheers
> Graham Turner
>
>
> Bergmann's Rule
>
>> From Wikipedia, the free encyclopedia
>>
> Jump to: navigation, search
> In zoology, Bergmann's rule is an ecogeographic rule that correlates
> latitude with body mass in animals.[1] Broadly it asserts that within a
> species the body mass increases with latitude and colder climate, or that
> within closely related species that differ only in relation to size that one
> would expect the larger species to be found at the higher latitude. The rule
> is named after a nineteenth-century German biologist, Christian Bergmann,
> who first formulated the rule in 1847. The rule is often applied only to
> mammals and birds (endotherms), but some researchers have also found
> evidence for the rule in studies of ectothermic species.[2] Bergmann's rule
> is controversial amongst researchers and its validity has often been called
> into question,[3] and there is division amongst scientists about whether the
> rule should be interpreted to within species variation or among species
> variation.[1] Although several mechanisms have been suggested to explain the
> rule there is no clear explanation for why the pattern exists.
>
>



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