New York City's Central Park may be surrounded by skyscrapers and enveloped in smog, but it is still a paradise for bird watchers. The May migration brings flocks of exotic species to this urban oasis--avian counterparts to the out-of-towners who crowd Times Square and Broadway. The high point is "Warbler Week," the perfect time for 15 bird lovers from the National Audubon Society to go on an early-morning expedition with David Allen Sibley, 39, author of the best-selling Sibley Guide to Birds (Knopf; $35) and, since the death of Roger Tory Peterson five years ago, America's most famous birder.
Leading the...