Mother-Infant Interaction and Behavioral Development in Southern Right Whales, Eubalaena Australis

Abstract

A quantitative study of infant behavioral development and mother-infant interaction in individually identifiable southern right whale pairs was conducted from August to December 1979 at Peninsula Valdes, Argentina. A period of rapid travel soon after birth is hypothesized to develop calf swimming competence, to enhance the ability of the thin, nonbuoyant calf to rise to the surface to breath, and to hinder detection by predators. Subsequent slowing of travel at 3-4 weeks of age leads to an increase in resting by the mother and an increase in play by the calf. Calf play is centered around the mother and may function to develop motor skills in behaviors useful in social, reproductive, and other contexts as an adult, though in play, calves exaggerated behaviors and combined them in ways different from adult behavior. Days before departing from the nursery area, rapid travel again predominated, presumably functioning to prepare mother and calf for the subsequent migratory period. Nursing comprised about 5% of calves' diurnal behavior throughout the season but the length of individual bouts increased with calf age. The mothers' needs to conserve bodily reserves during their 4 month fast at this time may conflict, in terms of individual reproductive strategies, with the calves' needs to develop motor abilities through energy consumptive play. Commencement of migration appears independent of calf age or size and is probably spurred by seasonal factors. Some yearlings and their mothers return to Peninsula Valdes and separate from each other there.