In this photo story, wildlife photographer, author and biologist Roland Hilgartner reveals this complex behaviour.
An aerial view of Loango National Park in Gabon. This protected natural paradise is a hotspot of biodiversity, containing a mosaic of different habitats including rainforest, wetlands, lagoons, savannahs, coastal rainforest, floodplains and mangrove forest. The park covers about 1,500km2 and is managed by Gabon’s National Agency for National Parks (ANPN).
The Rekambo chimpanzee community (rekambo means "where English is spoken" in the local language) consists of about 40 individuals. The Ozouga Chimpanzee Project team, led by Tobias Deschner and Simone Pika, head of the comparative biocognition research group at Osnabrück University’s Institute of Cognitive Science, has documented previously unknown chimpanzee behaviour in Gabon’s Loango National Park.
Sassandra, an infant Rekambo chimpanzee, enjoys a ride on her mother Suzee’s back. Female chimps eventually leave their natal group to integrate into a new one. It took the Ozouga Chimpanzee Project team more than 10 years to habituate this community and be able to observe their behaviour up close. The research project started in 2005.
In six years of collecting detailed data on the Rekambo chimpanzee community, the Ozouga Chimpanzee Project team has documented some startling behaviours, such as chimps attacking lowland gorillas, and even killing and eating one. They have also observed the use of tools, with chimpanzees using different-sized branches to dig out honey from underground beehives and crack open tortoise shells.
The first-ever photo of wild chimpazees and forest buffalo together. The Loango chimps’ extraordinarily large territories mean that encounters with large mammals such as forest buffalo or forest elephants are not uncommon. Researchers are studying how the chimps and other species compete for food.
A vigilant male, Chinois, scans the surroundings near the border of the territory. Chimpanzees patrol and defend territories, which can result in conflict with neighbouring groups – sometimes with lethal outcomes.
Alessandra Mascaro, an evolutionary biologist at Osnabrück University, first saw individuals within the Rekambo community treating their injuries with insects in 2019. Her PhD project now focuses on wound care and the substances used. One aim of her study is to find and identify the insect species the chimps catch to treat their wounds. In this photo, she searches the forest floor where Thea was sitting (see below) to find the insect that he applied to his wounds.
Thea, a male of the Rekambo chimpanzee community, suffered several injuries during a violent conflict within the group. The clash was a result of male chimps competing over females.
Thea immobilises an insect between his lips and crushes it. He then takes the insect out of his mouth and carefully applies it to an open wound on his left thigh, sustained during a fight with other males in the group. Thea repeats the procedure several times before finally cleaning the wound with his fingers.
Grooming is an important way to establish and strengthen friendships among primates. The treating of wounds may have a similar function and suggests that chimpanzees understand and care about the wellbeing of others. This possible prosocial behaviour is interesting for cognitive scientists because prosocial behaviours have been linked with high cognitive skills.
Oestrus is the most fertile phase of female chimpanzees’ reproductive cycles. They signal their receptivity with a shiny, reddish swelling of the genital region. These sexual swellings increase gradually in size throughout the female’s cycle and are very attractive for male chimps.
Thea shows his razor-sharp canines to rival males. To maximise their chances of reproductive success, males try to monopolise females in oestrus within their group. The competition can lead to severe aggression, often resulting in injuries among the males.
A white-bellied pangolin in the canopy of Loango’s rainforest. The national park is home to at least 80 species of mammals, including 11 species of primates. The park hosts one of the highest densities of forest elephants in the whole Congo Basin, and is also home to 272 bird species.
Two adult females, Ida and Suzee, have a rest on a fallen tree log, along with juvenile female Olive (left) and the infants Iboga and Sassandra. Group members always keep a vigilant eye on the youngsters of the Rekambo community.
Male chimpanzee Littlegrey enjoys a dip in a small river to escape the midday heat. Littlegrey is a special character because he loves bathing and being in the water. In contrast, most other Rekambo group members try to avoid getting wet, and cross rivers either on logs or on two legs.
Cesar, a young male, clutches a handful of coco plums (Chrysobalanus icaco) that he just gathered on the edge of the savannah. Chimps eat a wide range of foods including fruits, nuts, seeds and insects. The Rekambo territory spans about60km2 and takes in most of Loango’s habitat types.
