next message in archive
next message in thread
previous message in archive
previous message in thread
Index of Subjects
15, 2009 at 11:16 PM, Stephen Shaw < What I find objectionable is reporting speculation as fact. I would agree that migration is a hard business, and every year numbers of migratory birds do not survive the journey. We have been in and out of an estimated 22 major climatic variations in the last 2.4 million years, including four very major glaciations. Each time, fauna and flora have had to adjust, and those who were unable to adjust have presumably been winnowed out long since. A very minor change in world temperatures probably will not harm birds and other wildlife. If we consider the species which have become extinct since colonization, in our area there are rather few. We don't know what became of the Labrador Duck: it seems to have been uncommon, and the best guess is that molestation in its nesting area may have been a factor. The Ivory-billed Woodpecker lost its habitat due to drainage of swamps, and destruction of its forest habitat. The Passenger Pigeon was killed in huge numbers right at its nesting sites, in a way which eliminated it, even though it was one of the most common birds on the Earth. The Great Auk was also relentlessly persecuted in is nesting area. It we were to review all the cases, I think that it would be difficult to find a single bird species in North America which has gone extinct through climate variations. By far more important are factors such as: persecution while nesting; over-hunting for market; introduction of alien species (competitors and predators); and destruction of habitat. There is also the matter of pesticides, which at one time threatened the Osprey and the Bald Eagle; but we can report that both those species have recovered markedly. (I recently observed an eagle nest which has been producing young for nine years, located in a populated neighborhood in city of about 250,000 human inhabitants.) Of the major threats to bird life which I just listed, all can be controlled. Climate cannot be substantially controlled; and the proposals to attempt to do so are an attempt to administer a medicine which is far worse than the supposed disease. Can anyone really believe that the world will cut carbon-dioxide emissions by 80% within a decade, as some politicians have announced as a goal? That is absurd! This is what disturbs me: that the global warming issue has become not only politicized, but that it has become a state-supported, established ersatz-religion. It is propagated in the compliant media, and taught uncritically to students even in early grade-school. Perhaps I should not worry about this, because the public every now and then gets beset by some such raging fad; and ultimately, one may hope, everyone will learn the way things really work, and come back to reality. But in the meantime, do we have to make the lessons so darn expensive? On 16 Apr 2009, at 2:16 AM, Stephen Shaw wrote: > Not sure what Paul found so objectionable about this story, which > was perhaps > a low grade report (little value-added material) but was actually > excerpting > analyses and quotations from several researchers and the RSPBirds in > UK, not so > much giving the reporter's own opinion (or that of `the media`). > I didn't read it as suggesting that birds fly up seeking a particular > temperature value, but that the southern border of the habitat to > which they > are specifically adapted is moving further north quite rapidly > because of local > warming, presumably itself a result of global climate change. If > for example a > particular bird species is evolutionarily-programmed to migrate > north for a > certain average time or distance, &/or is programmed to recognize > exposed > tundra before it lands and tries to claim territory, it may wind up > exhausted > in boreal forest instead of tundra within a few decades, if the > northwards > trends in vegetation cover observed already continue. Food sources > there might > be sub-optimal. > The argument that small warblers seem to have made it through > earlier more > extreme climate changes just fine may be correct*, but misses the > point: other > species of small warblers may not have survived and become extinct, > because the > changes were too extreme for those particular species to adapt to. > We do not > now have these extinct species recorded or left to testify (few or > no fossils). > I don't believe that people who study it think that there is a > `motive for > migration` whether food or not. The proximate cause of migration > would be a > newly modified internal hormonal state (probably triggered by > daylength > changes) that elicits an anciently evolved behaviour to migrate, in > the brain. > The ultimate cause -- why such migratory behaviour evolved in the > past -- is > generally argued to be the lower density of predators and lessened > competition > for territory and perhaps food in the north; food (insects etc) > obviously needs > to be abundant, but is present in the summer both the winter grounds > and > temporarily in the northern habitat -- the difference is the > competition. Certainly no one argues these days that such behaviours > are purely instinctive > and unmodifiable, but equally some species may be less adaptable to > habitat > change than others and less able to survive climate shifts. > *or it may not be -- they may instead have survived further south > and then > gradually re-colonized the emptied northern zones as these warmed up. > > Quoting Suzanne Townsend <suzanne.townsend@gmail.com>: >> I knew if I posted it here, if it were off the wall someone would >> comment. >> Thank you Paul! Hope you post your comments at the source. >> --ST >> >> On Wed, Apr 15, 2009 at 8:01 PM, Paul S. Boyer >> <psboyer@eastlink.ca> wrote: >> >>> This is a good example of GW hysteria by the mainstream media, in >>> this case >>> by the highly unreliable Reuters. The article is pure >>> speculation. 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. >>> The principle problem for birds migrating between Europe and >>> Africa, like >>> those described in the article, is loss of habitat (particularly >>> in Africa). >>> It is also generally true that the bigger the bird, the more >>> likely it is >>> to be pestered by humans: chased, shot, eaten, &c. >>> >>> The conversion of temperature into an equivalent surface distance >>>