Habituation of Wild Black-and-White Ruffed Lemurs (Varecia variegata) in Vohibe Forest, Madagascar

Habituation is crucial for studying the behavioral ecology of wild nonhuman primates, but the process can vary between species and sites. Few studies have described habituation in lemurs. We initiated a long-term study of black-and-white ruffed lemurs (Varecia variegata) in Vohibe Forest, eastern Madagascar, by habituating 15 individuals from three subgroups over 12 weeks (January-April 2022). We characterize their habituation by assessing changes over time in subgroup behavior (all adults and juveniles) in the presence of observers using: 1) instantaneous sampling (5-min intervals) to quantify daily activity budgets (nine behavioral categories) and 2) all-occurrence sampling to quantify daily rates of six behaviors. Over 33 days, spanning 10 observation weeks and including 171.8 observation hours, we collected 297 activity budget data points and 198 all-occurrence data points. As habituation progressed, the proportion of time that we lost the groups and the proportion of time that they spent traveling decreased while the proportion of time spent feeding, self-grooming, resting, and being vigilant increased. The lemurs also significantly reduced the frequency of their alarm vocalizations and increased the frequency of fission-fusion events. Together, these changes suggest that the lemurs resumed more typical behavior as they became habituated to observers. We conclude that traveling, alarm vocalizations, and feeding are key indicators of habituation for the black-and-white ruffed lemurs. Habituation requires careful balancing of benefits and risks by taking precautions to mitigate negative effects. Our methods for habituating black-and-white ruffed lemurs can provide guidance for future studies.