Activity budgets and the effect of weather over a 10 year period in Critically Endangered yellow-tailed woolly monkeys (Lagothrix flavicauda) at El Toro, Peru

The study of animal activity budgets provides information regarding species' behavioural repertoire and how this can change over various time scales and due to external factors, both natural and anthropogenic. External environmental factors affecting animal behaviour vary on temporal and spatial scales, and include fluctuations in daily weather patterns, annual and long-term climatic variability, and the spatial and temporal distribution of resources, as well as inter- and intra-specific interactions. We present the results from the first long-term, 10 years, study of activity budgets of the Critically Endangered yellow tailed woolly monkey (Lagothrix flavicauda), a species endemic to high elevation forests in northern and central Peru. Our study took place at the El Toro field station which lies on the eastern slopes of the Andes in the Comunidad Campesina de Yambrasbamba in Amazonas Region, Peru. We collected behavioural data using instantaneous sampling on focal individuals. We analysed a total of 18,440 instantaneous samples, covering 3,073 h of survey effort, across 65 months between October 2009 and November 2018. Overall activity budgets for L. flavicauda were 30.3% 'Travel', 29.3% 'Rest', 27.7% 'Feed', 9.6% 'Forage', 1.5% 'Social' and 1.7% 'Other' behaviours. Our results are similar to the previously published activity budget for L. flavicauda at the site, and comparisons with other woolly monkeys show similar tendencies. There were significant differences in behaviours between age/sex classes with adult males resting more, juveniles the most social, and females foraging most. There was a trend of more foraging and resting during the dry season. We found lower incidences of resting and increased social behaviours correlated with higher minimum temperatures, and reduced social behaviour with increased precipitation. Better understanding of primate behavioural ecology and adaptability to temporal changes in environmental conditions and resource availability can help improve conservation strategies.