The Need to Feed: Differences in the Behavior of Black-Handed Spider Monkey (Ateles geoffroyi) Non-Lactating Females Versus a Lactating Female

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Primates have varying needs based on their life histories causing different members of the species to have different activity budgets. Lactating females require a higher nutritional intake to sustain lactation resulting in increased feeding. In the Osa Peninsula of Costa Rica, the activity budgets of three adult female black-handed spider monkeys (Ateles geoffroyi) were calculated to test the behavior of one lactating female (LF) and two non-lactating females (NLF). I hypothesized that LF will feed (feed, not moving and feed, moving) more than NLF to support lactation. A further prediction was that LF will spend less time with the other behaviors (rest; groom; and move, not feeding) than NLF. To record behavior, instantaneous focal sampling for three 10-minute sessions (one session per subject) was utilized with the behavior of one subject recorded at 30-second intervals for 10 continuous minutes. The following behaviors were evaluated: feed, not moving; feed, moving; rest; groom; and move, not feeding. The results found that the mean activity budget of NLF was: 65% rest; 25% move, not feeding; and 10% groom. Meanwhile, the activity budget for LF was: 30% rest; 40% move, not feeding; and 15% feed, not moving. For the remaining 15%, LF was out of sight and behavior could not be recorded. Thus, the first hypothesis is supported because LF fed more than NLF. However, the second prediction is partially supported because while LF groomed and rested less, LF moved more than NLF. The findings suggest that Ateles geoffroyi LF feed more to sustain lactation, but also move more which is likely due to foraging because of increased nutritional intake for lactation. Further studies would benefit from increased sample size, trial amount, and observational time since behaviors were only observed for 30 minutes with a limited number of individuals. Ultimately, the research demonstrates that members of the same sex within a species have varying behaviors, thus dividing their time differently based on needs, including maternal responsibilities.



Black-handed Spider Monkey, Ateles geoffroyi, Lactation, Activity budgets, Primates, Primate behavior