A Field Guide to the Birds , written and illustrated by Roger Tory Peterson. Published by Houghton Mifflin Co., Boston. Birds of North America , by the National Geographic Society. This guide also covers all birds of North America north of Mexico. Lenses can be purchased separately and are interchangeable.
Zoom lenses are available.
Spotting scopes are most practical for identifying birds across the wide-open areas of marshland, mud flats and lakes. Due to their narrow fields of view and the bulkiness demanded by their high-power magnification, they must be mounted on sturdy tripods to avoid shaky images. Sound tapes and CDs of bird songs and calls often are used at home and afield to identify birds. Learning the songs of birds will quickly expand your ability to distinguish one species from another. It frequently is the only way to identify species that remain hidden.