Sexual behavior of the North American Ruddy Duck (Oxyura jamaicensis), as summarized by Johnsgard (1965: 323-327), includes a display variously referred to as the ringing rush (Johnsgard 1965: 325; 1967), ring rush (Johnsgard 1966), and/or display flight (Johnsgard 1966, 1967), which males perform as a short rush across the water surface, generally toward females. Differences of opinion exist concerning the description of the sound emitted during the display and the exact mechanics of sound production. Bailey (1919) described "a noise suggesting castanets" accompanying what probably was the display flight. Johnsgard described the noise as ringing (1965: 325) and rattling (1967). Buzzing has been used to characterize the sound produced during the display flight of the Australian Blue-billed Duck (O. australis), a display "which appears to correspond exactly" to the ring rush of O. jamaicensis (Johnsgard 1966). We prefer to describe the sound as popping. Wetmore (1920: 247), without naming the display, described "a great boiling in the water with wings and feet." Johnsgard attributed the noise to the wings alone (1965: 325) and, later "wings and/or feet striking the water" (1967), while Palmer (1975: 513) assigned the sound to the feet.
