Population and Distribution of the Ashy Red Colobus Monkey in Community Forests in Biharamulo District, Northwestern Tanzania

This study was conducted in November 2024 using active observation searches and geospatial surveys to collect data. A total of 0.404357 km2 in the three forests was canvassed, and 108 individuals were observed. The study aimed to estimate the population and distribution of Ashy red colobus monkeys in three community forests in Biharamulo District, Northwestern Tanzania, where no previous research on the Ashy red colobus has taken place. A Bayesian negative binomial model and negative binomial regression model were applied to these findings to estimate 180 individuals in the three forests, with 40, 47, and 93 individuals estimated to reside in Nyamahanga, Karundi, and Mabila forests, respectively. An average group size of 15.43 individuals was observed. Ashy red colobus monkey distribution was restricted mainly to gullies and patches of dense canopy. These results of low populations, relatively small group sizes, and spatial restriction to certain areas indicate population decline due to habitat degradation and fragmentation. Management interventions are recommended to limit further habitat destruction and protect the persistent population of Ashy red colobus monkeys in the Nyamahanga, Karundi, and Mabila community forests.