Separation as a natural cue to danger in the spotted hyena (Crocuta crocuta).

Spotted hyena biology suggests mothers and infants will exhibit one of two alternative responses to separation: (a) Due to prolonged dependency, infants will act similarly to Old World monkeys, displaying distress and proximity seeking behaviors; or (b) because mother-infant separations are frequent in the wild, infants will exhibit little distress or change in reunion behavior. Hence, reunion behavior following mother-infant separation was compared to control periods in captive hyena (Crocuta crocuta) mothers and infants at two developmental periods. Significant increases (p < or =.05) in distress (i.e., agitated arousal and increased vocalization) and proximity maintenance (i.e., cub and maternal approaches, and maternal monitoring) as well as a trend towards increased sibling aggression following separation were observed. Responsibility for proximity maintenance, assessed by the Hinde Index, adhered to patterns common to primates---with cubs assuming increased responsibility later in development. Findings are discussed in light of hyena ecology and Attachment Theory.