Introduced in 1977 and completely revised in 1994, these bestselling
photographic field guides have become the birding bibles of more than
four million enthusiasts. Virtually every bird found in North America is
brought to life in a full-color photograph and with textual information
on the bird's voice, nesting habits, habitat, range, and interesting
behaviors. Accompanying range maps; overhead flight silhouettes;
sections on bird-watching, accidental species, and endangered birds make
these the most comprehensive field guides to birds available.
Note: the Eastern Edition generally covers states east of the Rocky
Mountains, while the Western Edition covers the Rocky Mountain range and
all the states to the west of it.