While a """"""""typical"""""""" howling monkey infant is primarily nutritionally dependent on its mother for its first eight months, and is not totally weaned until 18 to 20 months of age, infants without mothers (presumed dead) do survive. Ten infant/juvenile howling monkeys without mothers were compared with 19 similar aged howling monkeys with mothers in 5 free-ranging social groups on Hda. La Pacifica, Costa Rica. 750 hours of focal animal observations were done during June, July, and August, 1993-95. Data were converted to mean minutes or contacts per hour, and compared using ANOVA with age (0.8-1.5 yr., 1.6-2.5 yr., 2.6-3.5 yr.) and presence or absence of mother as independent variables. There were no significant differences in activity patterns (rest, feed, travel, play, other). Proximity to adult females was significantly more frequent in motherless howling monkeys in all age categories, but was most marked in the youngest age category. Proximity to juveniles was significantly higher for the youngest category of motherless howling monkeys, but was lower in the older age categories. Motherless infant/juveniles appear to compensate by being more sociable as infants and yearlings, and maintain proximity to adult females as juveniles.
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