The Periyar - Srivilliputtur and Agasthyamalai hills in the southern Western Ghats have some seemingly vast unbroken forest stretches in the entire Western Ghats. These hill ranges are contiguous except for a small break at the Shencottah gap. Because of the extent of forests, not surprisingly these hills contain a veritable biological diversity with several endemic species of flora and fauna. There are considerable forest stretches outside the existing network of Protected Areas in this landscape. These forests are a home to some of the globally endangered arboreal mammals such as the lion-tailed macaque (Macaca silenus), Nilgiri langur (Semnopithecus johnii), and the grizzled giant squirrel (Ratufa macroura). In addition to these species, other arboreal mammal species that occur in this region are the Hanuman langur (Semnopithecus priam), bonnet macaque (Macaca radiata) and the Indian giant squirrel (Ratufa indica). The goal of this project is to carry out a gap analysis to identify forests outside the PA network in Periyar-Agasthyamalai landscape, that are crucial for conservation of these diurnal arboreal mammals and to assess the existing Protected Areas for adequate representation of these species. The study aims to determine current distribution of arboreal mammals and ecological as well as anthropogenic factors governing their distribution in this landscape. This will be achieved through field surveys, questionnaire based surveys and information compiled from published literature. Information generated through this project will be used to envisage site specific conservation and management plans for these threatened taxa.