We know that races of birds that live in hotter climates are smaller
than the races that live in colder climates [ecologists refer to this
as Bergmann’s rule]. Just look at your field guide and compare the
tropical races with the temperate races.
Here are a couple of excerpts from the document:
"Decreasing size was associated with warming summer temperatures, at
least for species that bred locally. When regional temperature was
included along with year in the analyses of breeding adults, mass
decreased significantly with increasing temperature in the current and
the preceding year (Fig. 2; temperature this year: ..."
"Data from population trends indicate that declines in body size were
not associated with deteriorating conditions, at least during the
winter season or on the breeding grounds."
As for your comment regarding climate change, there are very
substantial facts outlined in:
Contribution of Working Group I to the Fourth Assessment Report of the
Intergovernmental Panel on Climate Change, 2007
• Preface and Foreword
• Summary for Policymakers
• Technical Summary
• Frequently Asked Questions
• Historical Overview of Climate Change Science
• Changes in Atmospheric Constituents and Radiative Forcing
• Observations: Atmospheric Surface and Climate Change
• Observations: Changes in Snow, Ice and Frozen Ground
• Observations: Ocean Climate Change and Sea Level
• Palaeoclimate
• Coupling Between Changes in the Climate System and
Biogeochemistry
• Climate Models and their Evaluation
• Understanding and Attributing Climate Change
• Global Climate Projections
• Regional Climate Projections
Nothing in this report has been discredited. You can read it for
yourself - download it from
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/contents.html
Regards, Laurie.
PS, There will still be believers and deniers even when we have
"perfect knowledge". That is the nature of humanity.
On 14/03/2010, at 3:09 PM, peter crow wrote:
I have no doubt that the data does indicate that song birds are
getting smaller. The problem is whether it is as a result of climate
change.
It seems that CC is being credited with possibly being involved with
many things when we don't really know.
i think associating results with climate change in this manner
"possibly as a result of" Doesn't do a lot of good.
I am not a CC believer, nor am I a denier nor am I a sceptic. I
simply don't have the background or knowledge to make a balanced
judgement.
I consider it highly likely that the amount of gunk we have poured
into the atmosphere has done no good and is "probably" causing all
sorts of things including "possibly" climate change.
We need substantial facts (as much as possible) to establish that we
have caused climate change so that we don't have "believers or
deniers."
We need facts that we mugs can understand and appreciate. Believing
or not believing are not options. We need knowers.
Peter
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