2.3 Field data collection
Behavioral data of the target langur group were collected for a full day and many other partial days throughout the study. During each full-day follow, the observations were recorded from when the monkeys left their sleeping sites to when they reentered their sleeping sites at the end of the day. During each partial-day follow, the data collection began when we first encountered the focal group and ended when they disappeared for over 30 min or entered a sleeping site.
The food items eaten (part and species) were recorded during instantaneous scan samples of 5 min with an interval of 15 min. During each scan, to avoid sampling bias toward certain individuals, the diet data were recorded for as many individuals as possible. If an individual was holding, chewing, or processing a food item, this was considered to be a feeding behavior. Additionally, the plant species that were eaten by the monkeys were recorded via ad libitum sampling; these records were used in a food species list but not for assessing the contributions to the monthly diet.