Assessment of macaque Population in the Yen Mo Limestone Complex, Ninh Binh Vietnam

As we surveyed the biodiversity of the Yen Mo Limestone Complex, particularly searching for the critically endangered Delacour’s langur, we observed the Assamese macaque (Macaca assamensis) and the Rhesus macaque (Macaca mulatta). While the macaques’ rock-climbing skills don’t match the cliff-hanging prowess of the Delacour’s langurs, they seem quite comfortable in the limestone landscape. In fact, they seem to be doing quite well. The thermal cameras of our drones revealed around 200 Assamese macaques in 15 groups and approximately 47 Rhesus macaques across our flights. At times, they would split and then regroup into large assemblies of up to 40-50 individual