this evidence of global warming is "for the birds"

The AP's Dina Cappiello calls it evidence of "global warming" (hat tip: C-J)

The C-J editor is more cautious in the choice of headline: "Global warming cited..."

First, this might be called regional warming, not "global warming". This is an example of global warming like the cold winter in Louisville is evidence of global cooling.

Second, the 40-year time is not all that useful, because it largely covers a time frame which everyone acknowledges has had a warming period. The question, instead, isn't whether there was warming from 1966-2005-- but the broader questions of longer time frames, cause-and-effect, and potential solutions (if they exist).

Third, they get to this later in the article, but it turns out that 1/4 of species studied have moved further south. While still statistically significant (I presume), it's not nearly as impressive as one might expect from the supposed strength of the thesis.

When it comes to global warming, the canary in the coal mine isn't a canary at all. It's a purple finch.

As the temperature across the U.S. has gotten warmer, the purple finch has been spending its winters more than 400 miles farther north than it used to.

And it's not alone.

An Audubon Society study to be released Tuesday found that more than half of 305 birds species in North America, a hodgepodge that includes robins, gulls, chickadees and owls, are spending the winter about 35 miles farther north than they did 40 years ago....

Bird ranges can expand and shift for many reasons, among them urban sprawl, deforestation and the supplemental diet provided by backyard feeders. But researchers say the only explanation for why so many birds over such a broad area are wintering in more northern locales is global warming.

Over the 40 years covered by the study, the average January temperature in the United States climbed by about 5 degrees Fahrenheit. That warming was most pronounced in northern states, which have already recorded an influx of more southern species and could see some northern species retreat into Canada as ranges shift....

The study of migration habits from 1966 through 2005 found about one-fourth of the species have moved farther south. But the number moving northward - 177 species - is twice that.

The study "shows a very, very large fraction of the wintering birds are shifting" northward, said Terry Root, a biologist at Stanford University....

Apparently, you don't need very, very much knowledge of basic math to teach biology at Stanford.

For other species, global warming may not be a major factor in the movements measured by Audubon at all. The wild turkey was second only to the purple finch in miles moved north - about 400. But it's likely due to efforts by hunters and state wildlife managers to boost its population....