White-thighed colobus (Colobus vellerosus) is a monkey species that contributes greatly to seed dispersal and tree regeneration through zoochory. Habitat degradation combined with intensive hunting throughout its geographic range has resulted in an inferred decline of more than 80% in the White-thighed colobus population over the past 27 years (Matsuda Goodwin et al., 2020). In the face of this situation, the species may become extinct in the near future if urgent conservation measures are not taken. The objectives of our report are to: (1) determine the factors of habitat degradation of white-thighed colobus in the Wari-Maro gazetted forest ; and (2) assess the degree of regression of white-thighed colobus habitats in the Wari-Maro gazetted forest. This report present the progression of the activities we are carring out on the species in order to inverse the species decline.