Surveying Delacour’s langur using unmanned aerial vehicle in Van Long Nature Reserve, northern Vietnam

Van Long Nature Reserve in Vietnam is probably well known for the biggest population of
the Critically Endangered Delacour’s langur, with 176 to 184 individuals in 2018. The
difficult-to-access terrain of limestone mountains makes it almost impossible to carry out
standard line transect and point count methods. Our drone tests in Van Long Nature
Reserve and Kim Bang Forest indicated that the drone Mavic 2 Enterprise Advanced is a
suitable tool for surveying the Delacour’s langur. We will use the done with a thermal and a
visual camera to detect, identify and count Delacour’s langurs in the nature reserve.