The rationale for this book has its origins in Terry Root’s 1988 Atlas of North American Wintering Birds, which provided a baseline landmark for evaluating the nationwide winter distributions of North American birds, using data from the National Audubon Society’s annual Christmas Bird Counts birds from 1962-63 through 1971-72. Tom Shane and I speculated that an updated analysis might shed light on the possible effects of more recent climatic warming trends on bird migration and wintering patterns in the Great Plains, a region known for its severe winters and also one of our continent’s important migratory pathways and wintering regions. As life-long residents of the Great Plains, we have both lived long enough to have witnessed some of these changes in avian migrations and wintering patterns personally. Johnsgard tested these speculations by doing some sample species analyses during the spring of 2008, after which it appeared that a complete survey of Great Plains winter birds would be worthwhile, based on Christmas Bird Count data.
Since the 1970’s there have been marked changes in avian habitats and regional winter climate patterns, and substantial changes in at least some Great Plains winter bird distributions and populations. In light of these changes it was decided that a survey of Great Plains winter bird populations over the past four decades might prove interesting, using Christmas Bird Count data mostly accrued since the time of Root’s landmark study, but using her results as a basis for temporal comparisons.
Mozilla Firefox users: There is a known bug in the Firefox PDF plug-in (which opens PDFs within the browser window) that will crash if a file exceeds its buffer size. It will tell you “The file is damaged and cannot be repaired” (which is not true). There are 3 remedies:
1. Right-click and download the PDF outside the browser (i.e., “Save link as ...”)
2. Change your Firefox settings to open PDFs with regular Adobe Reader (or Acrobat) instead of the plug-in version. This is reached under Tools > Options > Applications. PDF files will then open in a separate Adobe Reader (or Acrobat) window, not inside the browser window.
3. Download the file with Internet Explorer, Google Chrome, etc.
Available at: http://works.bepress.com/paul_johnsgard/124/