We use both Passive Acoustic Monitoring and close range recording to monitor langur populations and better understand their vocal repertoire. On a regional  level, Alexandra Hofner uses passive monitors to  record the loud call vocalizations of gray and purple-faced langurs to better define the distribution of these animals in the dry zone and their habitat use on a smaller scale in and around Kaludiyapokuna Forest. To date,  there is little known about the habitat use of the Northern subspecies of purple-faced  langur, however they appear to be confined to closed forests. In contrast, the gray langur can be found in a range of habitats including urban centers. With this multiscale project, we aim to publish better defined habitat requirements for these species to contribute to habitat protections.