Olin Sewall Pettingill, Jr., (October 30, 1907 – December 11, 2001), better known as Sewall Pettingill, was an American naturalist, author and filmmaker, president of the Wilson Ornithological Society from 1948 to 1950, a member of the Board of Directors of the National Audubon Society from 1955 to 1974, and a Life Fellow of the American Ornithologists' Union.
This is a fairly comprehensive guide to premier birding sites in the West. I recently used this guide (May, 2006) while preparing for a trip to North & South Dakota. The book (along with excellent guide, Jeanne Legge) helped me find 3 breeding target birds of the prairies: Sprague's Pipit, Baird's Sparrow and McCown's Longspur in the Amidon & Rhame area of North Dakota.