Harold Ford Mayfield (25 March 1911 – 27 January 2007) was an American business executive and amateur ornithologist who made a major study of Kirtland's warbler and worked for the preservation of their breeding areas. During his study of the warbler, he introduced a standardized measure of nesting success based on his professional experience in industry and from his training in mathematics. This method now widely known as the Mayfield Method involves probability calculations that take into account nests that the observer was unable to locate. Prior to his work, ornithologists used naïve approaches based on fractions of number of successful young or nests from a total of nests that they had found.
