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food. They certainly can tolerate temperature extremes much better =20
than unprotected humans.

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Canada Geese have largely given up migration entirely, because they =20
find it easier to graze on man-made lawns than to make an arduous =20
migration flight.  This certainly does not indicate that the seasons =20
have ceased to occur.

I have not been able to find a single convincing case of a migration =20
problem which would be caused by a change in a fraction of a degree.  =20=

Indeed, the severity of winters from year to years varies by much more =20=

than that.

There is much we do not understand about bird migration.  There is =20
also much we have to discover about changes in bird population.  Our =20
lack of complete knowledge is no reason for us uncritically to believe =20=

every tendentious news story which comes along.


On 15 Apr 2009, at 2:03 PM, Suzanne Townsend wrote:

> =
http://www.reuters.com/article/environmentNews/idUSTRE53D7G220090415?feedT=
ype=3DRSS&feedName=3DenvironmentNews


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<html><body style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; =
-webkit-line-break: after-white-space; ">This is a good example of GW =
hysteria by the mainstream media, in this case by the highly unreliable =
Reuters. &nbsp;The article is pure speculation. &nbsp;It also ignores =
the fact that the Earth was warmer just 7,000 years ago, and colder =
during the Little Ice Age, and warblers seem to have made it through =
those changes just fine.<div><br></div><div>The principle problem for =
birds migrating between Europe and Africa, like those described in the =
article, is loss of habitat (particularly in Africa). &nbsp;It is also =
generally true that the bigger the bird, the more likely it is to be =
pestered by humans: chased, shot, eaten, =
&amp;c.</div><div><br></div><div>The conversion of temperature into an =
equivalent surface distance needed for migration assumes that =
temperature is the main control of bird migration, which almost everyone =
who has studied the subject knows is just not true. &nbsp;Food is the =
main motive for migration, and the food needs vary according to species. =
&nbsp;Birds will put up with a wide range of temperatures, if the food =
is available. &nbsp;That is the reason so many feeder-species have moved =
north, and now stay longer in the winter: if the food is adequate, they =
will stay. &nbsp;It is one of the amazing things we observe: tiny little =
creatures, out in the cold, with nothing but a thin layer of puffed-out =
feathers to separate them from freezing =97 and yet they can handle =
this, if they have enough food. &nbsp;They certainly can tolerate =
temperature extremes much better than unprotected =
humans.</div><div><br></div><div>Canada Geese have largely given up =
migration entirely, because they find it easier to graze on man-made =
lawns than to make an arduous migration flight. &nbsp;This certainly =
does not indicate that the seasons have ceased to =
occur.</div><div><br></div><div>I have not been able to find a single =
convincing case of a migration problem which would be caused by a change =
in a fraction of a degree. &nbsp;Indeed, the severity of winters from =
year to years varies by much more than =
that.</div><div><br></div><div>There is much we do not understand about =
bird migration. &nbsp;There is also much we have to discover about =
changes in bird population. &nbsp;Our lack of complete knowledge is no =
reason for us uncritically to believe every tendentious news story which =
comes along.</div><div><br></div><div><br><div><div>On 15 Apr 2009, at =
2:03 PM, Suzanne Townsend wrote:</div><br =
class=3D"Apple-interchange-newline"><blockquote type=3D"cite"><a =
href=3D"http://www.reuters.com/article/environmentNews/idUSTRE53D7G2200904=
15?feedType=3DRSS&amp;feedName=3DenvironmentNews">http://www.reuters.com/a=
rticle/environmentNews/idUSTRE53D7G220090415?feedType=3DRSS&amp;feedName=3D=
environmentNews</a></blockquote></div><br></div></body></html>=

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