Thanks Rick and Shawn for the excellant points. Please read the full report (the summary is only 14 pages long) where all are addressed (http://www.audubon.org/news/pressroom/bacc/pdfs/Birds%20and%20Climate%20Report.pdf). Remember that this is a summary of the results of the analysis not the analysis itself and it is further summarized in the popular press. It is also important to keep in mind that these numbers reflect population shifts over a 40 year timespan not individual birds or small groups of birds.
Specifically, note that the trend toward colder latitudes correlated with temperature. The movement toward colder latitudes was recorded in 177(58%) of 305 species not just feeder birds or introduced species. Species also shifted from warmer coastal areas to cooler inland areas. Most important though is the shear numbers, this is a phenomenon documented hemisphere-wide and to the majority of avian species. Although local habitat change, feeding, and increased observations may provide local changes, the type of colossal changes that must occur to affect almost all avian species in the entire hemisphere gives strong credence to the global warming hypothesis. Combine this with the correlation to temperature, the shift from coastal to inland, and the long-term (40-year) availibility of data and there is a high-degree of confidence that global temperature change is playing a predominant part in the range shifts. The paragraph below is a quote from the report summary. "Birds frequently alter their ranges due to many factors, especially habitat changes and interactions with other species. Audubon does not suggest that all the birds that moved north or inland did so in response to climate change; a wide variety of other factors play a contributing role and explain why a minority of species showed no movement or even shifted southward. However, the correlation between shifting ranges and winter temperature trends cannot be ignored in explaining some of the widespread and directionally consistent movements seen among U.S. bird species. Among key findings: 1) Annual latitudinal distributions of birds are correlated with annual temperatures. 2) Among states and provinces, rates of bird population change are correlated with rates of temperature change, independent of latitude. 3) Among all the species in our study, twice as many bird species moved north as south; twice as many species moved inland as moved coastally. Both of these directional movements are consistent with a climate change model. However, an equal number of birds moved east as moved west. Under global warming, movements away from the Atlantic and Pacific should be about equal, with no other expectation of differences in east-west movement. 4) Latitudinal movement patterns among birds centered in different latitudinal regions of North America are generally consistent with a climate change model, but inconsistent with movements predicted as a result of range shifts in response to population increases or decreases. 5) Birds found only in a few southern states, and thus not included in the main part of this study, have been observed in increasing numbers, suggesting that they have moved north from south of the United States. " Carl Greiner -------------- Original message from Rick <[email protected]>: -------------- > I agree with Shawn in this case. It seems to me that the case is some > what over stated in the Audubon article. I have not doubt that Global > warming is a problem that we all need to be concerned about; However, > Wild Turkey expansion is not a good example since they very wide spread > at one time then, the population was decimated and now with > re-introduction they are simply moving into areas that they previously > inhabited. > > Rick > > shawn conrad wrote: > I'd like to preface this bay saying first that this is > in no way directed toward Gordon as I appreciate him posting this and second > that I am NOT a global warming doubter, I DO believe the prevailing > scientific opinion regarding the role of human beings in global warming, and > I realize that warming of even a few degrees will likely result in > significant problems for humans and nature alike. > However... > > > > > > > I did visit this link, the report, and I did read the article on this > > > report > in the STrib and I think Audubon is probably painting an incomplete picture > here. Basically, they are saying that CBC data shows birds wintering or > residing far north of their historic ranges so global warming must be the > culprit...and they might be right, global warming may be a factor. > > > > > > > > However, does anyone believe that global warming alone has moved Purple > Finches 400 miles already? > > > > > > > > I don't think ornithologists are being fair to anyone to completely gloss > > over > the effects of the increased popularity and sophistication of bird feeding, > changes in habitat (both "good" and bad), and increased observer coverage. > Corridors of development filling in farther north may be helping > human-adapted > or disturbance-adapted birds move north. Increased availability of fruit in > the > north like Common Buckthorn (bad!) and planted crabapples may sustain more > birds > in the winter. Habitat loss to the south may discourage birds from returning > to > wintering grounds. Increasing forest age in the north (regrowth from logging > heydays) may create habitat for more birds in the north. More people looking > for birds in the north increases observations. > > > > > > > > I don't know if all of these are a factor, and I could probably sit here > > and > hypothesize more. But, certainly some of them are a factor and none of them > are > addressed at all in the Audubon report...at least not where the casual > observer > would find them. > > > > > > > > Again, global warming probably is a FACTOR...especially with birds of the > boreal spruce forest like Spruce Grouse receding on the southern edge of > their > range. But, we need to be honest that there are likely compounding > explanations. This doesn't mean that global warming isn't a serious problem. > What it does mean is that it is an additional stress combined with other > stresses that we also need to address, like overdevelopment. > > > > > > > > This is especially important for nonbirders to understand. I can't count > > the > number of times nonbirders have asked me about the robins they have seen this > winter or the cardinals increasing up north and whether global warming is the > reason. Generally, I tell them it's not quite that simple and ask them how > much > time they have to hear my thoughts... > > > > Shawn Conrad > > > > http://users.2z.net/itasca_chippewa_birding/ > > > > > > > >> > >> > >> Check out www.birdsandclimate.org. > >> > >> > >> > >> > >> > >> > >> > >> > >> > >> > >> > >> > >> ---- > >> Join or Leave mou-net:http://lists.umn.edu/cgi-bin/wa?SUBED1=mou-net > >> Archives:http://lists.umn.edu/archives/mou-net.html > >> > > > > _________________________________________________________________ > > Want to do more with Windows Live? Learn “10 hidden secrets” from Jamie. > > > http://windowslive.com/connect/post/jamiethomson.spaces.live.com-Blog-cns!550F68 > > 1DAD532637!5295.entry?ocid=TXT_TAGLM_WL_domore_092008 > > ---- > > Join or Leave mou-net:http://lists.umn.edu/cgi-bin/wa?SUBED1=mou-net > > Archives:http://lists.umn.edu/archives/mou-net.html > > > > > > > > > > ---- > Join or Leave mou-net:http://lists.umn.edu/cgi-bin/wa?SUBED1=mou-net > Archives:http://lists.umn.edu/archives/mou-net.html ---- Join or Leave mou-net:http://lists.umn.edu/cgi-bin/wa?SUBED1=mou-net Archives:http://lists.umn.edu/archives/mou-net.html
