Instantaneous sampling of eight behavior categories for a captive mother sea otter (Enhydra lutris) and her four pups was conducted continuously during the first three months following each pup's birth. Initially, pup-grooming and rest occupied the largest proportion of the mother's time. Despite a steady decline in the amount of time the mother spent pup-grooming, the mother continued to groom the pup a substantial amount of time three months after the pup's birth. The proportion of time the mother spent resting, self-grooming, or swimming did not change significantly over the study period, suggesting that these behaviors are important to the mother's self-maintenance.The newborn pups' behaviors were initially limited to rest, active, and nursing, with large proportions of time spent resting and nursing. A significant increase in self-grooming occurred regularly by week 2, followed by increases in swimming (week 3), diving (week 6), and feeding (week 7). Three months after birth, the pups' behavior budgets were similar to their mother, with the exception that pups self-groomed substantially less than their mother self-groomed. The lower proportion of pup self-grooming may be due to the continued close proximity to their mother in captivity, which afforded extended association, and allowed the mother to continue to perform this complex behavior for the pup. 0 1993 WiIey-Liss, Inc.

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Five laboratory-born infant pigtail macaques (Macaca nemestrina) were studied during playroom interactions. Each infant was videotaped for a 5-minUte period weekly for 5 months. The animals were scored on the frequency of the mouth display observed. Both play-type (round mouth corners, ie, relaxed open-mouth display) and fear-type (sharp mouth corners, ie, silent bared-teeth display) facial expressions were present at the onset of observations. Play mouths appeared with greater frequency than fear mouths throughout the study. The frequency of round-cornered mouths (play and gnaw) vs sharpcornered mouths (bite and grimace) was significantly different both across monkeys and across weeks. There appeared to be a bimodal distribution of round and sharp mouths, with infants using the different mouth types in anonsocial context at earlier ages and in a social context as they matured. The data are consonant with a phylogentically separate origin of the fear grimace and playface in old world anthropoids including humans.

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