Then there are tree swallows, which are showing up to their U.S. breeding grounds about 12 days earlier than they were 30 years ago, according to Hector Galbraith at the University of Colorado at Boulder.
"The result in and of itself would be interesting but hardly worrying," Galbraith said. "But when you look at other [bird] species and see this 10-to-12-day change crop up in tons of those, it is [worrying]."
And this is not just coming from tree swallows:
In 2003 Stanford's Terry Root found many examples of global-warming-spurred behavioral shifts in a review of 143 scientific studies covering 1,473 species of plants and animals.
"If you look at all the studies that have been done on species and climate change and find the same signature for species all around the globe by many, many individuals instead of just one or two, it gives circumstantial evidence" that global warming is driving the changes, she said....
Galbraith, who co-authored a 2004 report for the Washington, D.C.-based Pew Center on Global Climate Change, said the behavioral shifts are anticipated, but they are coming about 15 years earlier than he expected.
"One important message from the Pew report is we're already seeing these effects, and they're widespread … the effect is way ahead of when many people in the field would have predicted," he said.
Ultimately, we are probably going to be looking at extinctions, though how many depends on how much and how quickly the earth warms.