Using local knowledge and camera traps to investigate occurrence and habitat preference of an Endangered primate: the endemic dryas monkey in the Democratic Republic of the Congo

The Endangered dryas monkey Cercopithecus dryas, endemic to the Democratic Republic of the Congo, is one of Africa's most enigmatic primates. The discovery of a dryas monkey killed by a hunter in the buffer zone of Lomami National Park in 2014 prompted field research on the species’ distribution, habitat use and stratum preference. We used local knowledge to determine the distribution of this species and to select sites for camera-trap surveys in Lomami National Park and its buffer zone. We employed a multi-strata (0-29 m) camera-trap placement technique to determine habitat use at Camp Bartho in Lomami National Park and Bafundo Forest in the Park's buffer zone. We confirmed the occurrence of the dryas monkey at seven locations over a total area of 3,453 km2, in both the Park and its buffer zone. Dryas monkeys were detected most frequently (2.22 events/100 trap-days) in disturbed areas of Bafundo Forest and less in mature forest in Camp Bartho (0.82 events/100 trap-days). Dryas monkeys appear to prefer structurally complex understories and forest edges. We found that camera traps at 2-10 m above ground over at least 365 trap-days are required to determine if the species is present. We recommend utilizing local knowledge and using this species-specific camera-trap method in other areas of the central Congo basin to determine the wider distribution of the dryas monkey.