Nurturant behavior towards a dead calf in a Cuvier's beaked whale

Abstract

Epimeletic behavior was defined by Scott (1958) as care or attention or care-giving to another individual, living or dead. It is also referred to in the literature as care-giving, nurturant, succorant, or supportive behavior. Caldwell & Caldwell (1966) termed nurturant behavior as a form of epimeletic behavior directed towards an individual in distress, especially conspecific juveniles or infants (Reggente et al., 2016). Nurturant behavior has been documented in various social mammalian species, both terrestrial and marine. In the case of the cetaceans, it has been described in a wide variety of toothed whales, both in captivity and in the wild, with an extensive peer-reviewed scientific literature on the subject (Reggente et al., 2016(Reggente et al., , 2018Bearzi et al., 2018). While "care-giving" behaviors towards living conspecifics has a clear adaptative significance, when directed towards dead conspecifics its evolutionary purpose is less obvious (Bearzi et al., 2017). Reggente et al. (2018) presented a comprehensive review of 106 cases of death-related behaviors in aquatic mammals (81 cetaceans and 25 noncetaceans) from published and unpublished literature. The authors showed that cetaceans, often with long maternal investment, respond to death-related behaviors in different ways from noncetacean aquatic mammals.Deep-diving toothed whales of the family Ziphiidae are among the least known of all marine mammals due to a combination of factors such as their oceanic offshore habitat, their ability to make deep and prolonged foraging dives, short surface bouts and elusive behavior (