The Peterson Identification System is a practical method for the field identification of animals, plants and other natural phenomena. It was devised by ornithologist Roger Tory Peterson in 1934 for the first of his series of Field Guides (See Peterson Field Guides.) Peterson devised his system "so that live birds could be identified readily at a distance by their 'field marks' without resorting to the bird-in-hand characters that the early collectors relied on. During the last half century the binocular and the spotting scope have replaced the shotgun." As such, it both reflected and contributed to awareness of the emerging early environmental movement. Another application of this system was made when Roger Tory Peterson was enlisted in the US Army Corps of Engineers from 1943 to 1945. “..