Don Stap describes Parker's method: walking slowly down a trail, pausing after every step, and watching and listening.
[3] In this way he gained his knowledge of both detail and "common patterns in behavior or vocalizations or community structure across the continent",[4] which led Jon Fjeldså and Niels Krabbe to call him "by far the greatest specialist on the life histories of neotropical birds there ever was".
[1] Parker willingly shared his knowledge with others informally, published extensively, and contributed over 10,000 recordings to the Macaulay Library of Natural Sounds[6] at the Cornell Laboratory of Ornithology.
Parker was doing a survey for it in western Ecuador when he was killed in a plane crash along with three others, including the botanist Alwyn Howard Gentry.
[7] The Theodore A. Parker III Natural Area[8] in Lancaster County, Pennsylvania, and the Parker/Gentry Award for Conservation Biology[9] are named for him.