Courtship of the American Redstart

Abstract

COURTSHIP has been described by Morris (1956b: 261) as "the hetero-sexual reproductive communication system leading up to the consummatory sexual act," and thus encompasses activities from pair formation through copulation. Courtship in the American Redstart, Setophaga ruticilla, is roughly divided into three periods: pair formation, pre-nest building, and nest building. The behavior during each is described. The causation, function, and derivation of some of the displays are postulated. Definitions of some terms and methods used in analyzing displays are described elsewhere (Ficken, 1962) and generally follow the methods of Tinbergen (1959). Approximately 12 pairs were studied intensively during the courtship period in the course of three seasons (1957-1959) in Renwick Bird Sanctu-ary, Ithaca, New York. Individuals were distinguished by differences in color and/or pattern. Many other pairs were studied more casually and a hand-raised male and female were observed in captivity. AGONISTIC DISPLAYS Agonistic behavior of the species is discussed in detail elsewhere (Ficken, 1962), but since some intra-pair agonistic displays occur during the court-ship period, they are mentioned briefly here. Song. There are two principal song types, the Accented Ending Song predominating during territory establishment and pair formation and then declining, while the Unaccented Ending Song increases in relative frequency later in the season. Some songs uttered near the female are muted. Harsh Chip. This is frequently given by the female. When it is uttered slowly the male often approaches; when it is uttered rapidly he retreats. Zeep. This flight call is more frequently given by the female and may function in keeping the male informed of her location. Snarl. This is a threat often given by the female when the male ap-proaches very closely, and frequently precedes her attacks. Bill Snaps. These sometimes occur as the female lunges at the male. Circling. A Circling flight with ritualized wing movements is common in encounters between males at boundaries. The male occasionally per-forms Circlings toward the female (probably indicating a hesitancy to approach) but these lack the ritualized wing movements. Fights. As in male-male encounters, the male and female strike at each other without contact. Fights occur when the male approaches too closely and are apparently initiated by the female.