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Camera traps help us study Grauer’s gorillas and other endangered animals in Nkuba.

The Congo Basin holds the second largest tropical rainforest in the world and is home to numerous species of plants and animals, many of them threatened or endangered. Doing research and engaging in conservation in the area, particularly in the eastern part of the Democratic Republic of the Congo, is difficult and dangerous, but understanding the challenges the region faces is of global importance as we race to solve problems such as climate change, deforestation and species extinction.

We know that there are many species in the forest in need of our protection, but how can conservationists determine which animals are there, and in what numbers, without interrupting their day-to-day activities through our presence? Many parts of the forest are difficult to access—and it’s important to keep them that way in order to ensure that their biodiversity remains intact.

grauers gorilla on camera trap
A Grauer’s gorilla passes by a camera trap in the Nkuba Conservation Area. Grauer’s are critically endangered and efforts to create an accurate head count continue.

That's where camera traps come in.

A recent study by Fossey Fund scientists used more than 16,000 days’ worth of camera trap images and transect surveys to obtain data on which animals are present in the Nkuba Conservation Area—a 1,583 square kilometer community forest that the Fossey Fund helped establish and now manages. The team identified 33 separate mammal species, seven of which—the Grauer’s gorilla, eastern chimpanzee, owl-faced monkey, giant and white-bellied pangolin, leopard and African golden cat—are categorized as threatened on the IUCN Red List.

“To explore these forests, we set the cameras up in a sort of grid with a fixed distance between them,” says Dr. Yntze van der Hoek, a biodiversity researcher with the Fossey Fund and lead author on the paper. The precise location of each camera was determined by the presence of animal signs such as footprints, or by locating bodies of water and other places where animals would presumably pass by frequently. The team then affixed the cameras to sturdy trees that weren’t obstructed by other vegetation in order to have as clear a view as possible.

Bongo caught on camera trap
The bongo is a large but elusive forest antelope that is mainly active at night.

Collecting the actual data from the cameras involves yet another trip into the forest. “To minimize our environmental impact, we use rechargeable batteries, which means we need to recharge the batteries every month or so,” says Urbain Ngobobo, a coauthor on the paper and director of the Fossey Fund’s program in DR Congo. Each month team members hike into the forest to collect the spent batteries, bringing them back to camp to 

charge. At the same time, they retrieve the memory cards so they can see what animals have been captured by the cameras.

Do the traps influence animal behavior? Probably not, says van der Hoek. “The cameras we use make little to no sound and use infrared rather than flash to capture images at night. Some animals do show curiosity about the cameras. But we also see a lot of footage of species engaging in natural behaviors—even sleeping in front of the cameras. So we believe the effects on animal behaviors are minimal.” 

The images captured on film are impressive, but more importantly, they give scientists a great deal of information about the many elusive species that make their home in the Congo Basin. The team was able to estimate the number of individuals in certain species that live in the Nkuba Conservation Area, as well as track their movement and distribution patterns—where they gather and which areas they avoid. The study also added to our understanding of the ecological and behavioral traits of these animals—which hours of the day they are most active, whether they live in groups and whether they associate with other species (for example, certain monkeys are often found together with antelopes).

A family of Grauer’s gorillas stops for a rest in front of a camera trap.
servaline genet caught on camera trap
The servaline genet pictured here is a very agile carnivore with retractable claws well-suited for climbing trees.

The presence of threatened species, including critically endangered Grauer’s gorillas, as captured in these camera traps, tells conservationists that the Nkuba Conservation Area harbors a forest community in need of continuous monitoring, further research and investment in protection from the ongoing deforestation and resource exploitation occurring in the surrounding region.

“These findings will help us guide future research and effective conservation actions,” says van der Hoek. “It was also really interesting to learn which species were roaming around our tents at night while we slept.”

Read the full study here.