Variation in Guiana dolphin parental care according to calf age class

Abstract

An extended period of parental care is fundamental for survival of cetacean offspring. Although qualitative descriptions of parental care and mother-calf spatial relationships are available for several species, studies using a quantitative approach throughout development of offspring are scarce. Here, we analyzed how strategies of parental care occur during the ontogeny of the Guiana dolphin, Sotalia guianensis, in the Cananéia estuarine system, São Paulo, Brazil. We tested the hypothesis that both the strategy and frequency of parental care vary according to the development of the offspring and assessed whether such changes are associated with the life stage of the calves. The frequency of parental care did not decrease according to the age of the calves. However, parental care strategies directed at infants were more diversified than those directed at neonates and juveniles. Increasing maternal-calf separation can expose older calves to new and risky situations and may demand different strategies of care. We conclude that there is a shift in the strategy adopted by the S. guianensis mothers according to the requirements of each age class, with parental care being dispensed until calves become fully independent.