JON L. DUNN and JONATHAN ALDERFER are the authors of many of National Geographic's renowned birding books, including the 7th edition of the Field Guide to the Birds of North America, called "canonical" in a recent review. Dunn, a popular birding tour guide worldwide, has long been a leader within the American Ornithological Society and the American Birding Association. Alderfer, one of the nation's foremost bird illustrators, is well known as an authority on North American birds and an expert field bird-watcher. See his art at www.jonathanalderfer.com. Alderfer lives in Edgecomb, Maine; Dunn lives in Bishop, California.