Bonobos are one of our closest relatives and are only found in the Congo. The largest bonobo population lives in Salonga National Park, the largest forest reserve in Africa. It is now clear exactly how many of the critically endangered bonobos are native to the forest.
Along with chimpanzees, bonobos are our closest relatives. Unlike them, however, they live exclusively in the Democratic Republic of Congo, primarily in Salonga National Park. This is the size of Switzerland and therefore the largest forest reserve in all of Africa. The bonobos find protection there from poaching and habitat loss. But exactly how many of the critically endangered bonobos live in Salonga National Park has long been unclear.
“There was an old number circulating, but that was an assumption based on surveys that covered less than twenty percent of the entire park,” says Barbara Fruth from the Max Planck Institute for Behavioral Biology. It would be important to know the bonobo numbers throughout the park: “In this huge country, only Salonga offers the opportunity to model trends and assess whether the bonobo population in the Congo is declining or not.”
All surveys under one roof
Fruth and her colleagues have now determined the size of the bonobo population in Salonga National Park more precisely than ever before. To do this, the team summarized 13 surveys from 2002 to 2018 that focused on counting bonobos in Salonga National Park. Various counting methods were used, such as recordings from wildlife cameras, counting bonobos nests and exploratory hikes.
The evaluation shows: There are around 8,000 to 18,000 adult bonobos living in Salonga National Park. The size of the population has remained roughly the same since 2000. Nevertheless, the team found that the density and distribution of great apes is decreasing. “This means that the bonobos there are not under immediate threat, but we must remain vigilant and continue to invest in conservation efforts if we want to ensure their survival,” warns lead author Mattia Bessone from Liverpool John Moores University.
Feared and valued people
The forest in which they live is particularly important for the preservation of the critically endangered bonobos. However, the national park is divided into two parts by a 9,000 square kilometer corridor inhabited by humans. The great apes stay away from these human settlements and villages, the research team found. However, they are not entirely skeptical of people either. For example, they spend more time near ranger posts. “We cannot say what the rangers specifically do that we see this effect,” explains Bessone. “But it could be that rangers are a potential deterrent to poachers. Whatever the reason, it is clear that the mere presence of these sentinels has a positive impact on bonobo presence.”
In the southern part of Salonga National Park, there are people from a traditional minority who also seem to be well disposed towards the bonobos. Even before the park was founded in 1970, the minority settled here in villages. “In these villages there is a cultural taboo that prohibits hunting bonobos,” says Bessone. “This could be the reason for the positive influence they have on the bonobo population.” However, deforestation and hunting of the great apes remain a threat.
Source: Max Planck Institute for Behavioral Biology; Specialist article: International Journal of Primatology, doi: 10.1007/s10764-024-00468-w