A new report has been issued by the National Audubon Society based on data gathered by our Christmas Bird Counts. An exerpt:
"We were able to look at the winter distribution of 305 species to see if their winter range had shifted over the last 40 years. We discovered that 177 of these species showed a significant shift north and this northward shift was correlated with an increase in mean January temperatures in the contiguous 48 states of almost 5 degrees during that time."
Check out the Audubon Website for more details and to download the report (in PDF form).
