A scream erupted at dawn on the savannah, followed by other screams and the rustling of branches: wild Fongoli chimpanzees wishing each other good morning in the dry and stingy Sahel.
The rare chimpanzees — who live in the hot bush of southeastern Senegal, rather than the forest as is more common — exist at the extreme edge of what is possible for their species.
Their unusual way of life offers clues to humans’ own evolutionary past, while their adaptations to heat seem timely in a world where temperatures are rising.
Soaking in pools, cooling off in caves and even wielding spears: The 35 wild chimpanzees in the Fongoli community have adapted to their environment with behaviors that defy the conventional norms of their species.
Now, 25 years after she began her pioneering research on savanna chimpanzees, which had never been accustomed to observers, primatologist Jill Pruetz has a wealth of data.
The longevity of the study allows for a deeper dive into the Fongoli community’s behaviors, relationships, and how they learn from one generation to the next.
“Until they got used to observers so we could track them and take data, we only knew chimpanzees in forested areas,” Pruetz told AFP reporters, who spent two days following her and her team as they followed the primates into the bush.
The Fongoli chimpanzees, which live on a home range of 100 square kilometers (40 square miles), are just one group of savanna chimpanzees in the region, but for years the only one that has been studied.
On a recent morning, AJ, Raffy, Diouf, and the ambitious young Pistache sat atop a baobab tree, plucking a breakfast of fruit that they opened with a swing of the branches.
By screeching, or “yelling,” as their vocalizations are known, they communicated with other members nearby.
Pruetz and her team of Senegalese researchers track the group’s adult males, which currently number 10, choosing one each day to watch from dawn to dusk. Females, however, are not tracked to keep them more alert to poachers.
The strict male hierarchy runs from Cy, the alpha, to Siberut, the oldest and lowest-ranking, despite his superb hunting skills.
Because social monkeys spend much of their time together, Pruetz is still able to observe females and their young.
Females have proven to be the most innovative members of the clan: they are the only non-human animal that systematically uses tools to hunt.
It’s a behavior that Pruetz and her researchers have observed nearly 600 times.
– “Hottest Zone” –
After cutting sticks into spears, usually with their teeth, the females hunt bushlings during the rainy season, impaling the small primates as they take shelter in tree holes.
With the heat index reaching 49 degrees Celsius (120 degrees Fahrenheit) in the hot season, life on the savannah can be exhausting.
Fongoli chimpanzees “have to deal with the hottest area where we’ve studied chimpanzees,” Pruetz said, and they have to “minimize energy expenditure” during the dry season.
They are the only wild chimpanzees in the world known to bathe in natural pools. In addition, they “use caves to rest because caves are cooler,” Pruetz told AFP.
The savannah forests that are the habitat of Fongoli chimpanzees are similar to those in which human ancestors lived about six or seven million years ago.
By looking at chimpanzees, which along with bonobos are humans’ closest relatives, perhaps “we can help confirm some of the hypotheses about how these really early hominins, or bipedal apes, behaved,” Pruetz said.
While the many adaptations of Fongoli chimpanzees mean they are able to cope with “high heat stress,” Pruetz said, “we’re not sure that with climate change they can continue to do that.”
– The Gold Rush –
Fongoli monkeys are members of the critically endangered West African subspecies of chimpanzees.
Although they have traditionally coexisted with humans in their home range, a new threat has emerged: a gold rush that has led to an increase in both artisanal and industrial mining.
In the morning, the sound of stone crushers grinding through buckets of substrate could be heard before the fauna of the savannah began its daily chorus.
The fires burned at the artisanal mines, where the night watchmen watched over the equipment.
Mines can mean water pollution, greater resource extraction and the spread of human diseases to chimpanzees.
Papa Ibnou Ndiaye, a wildlife researcher and professor at Cheikh Anta Diop University in Dakar, said studying the Fongoli chimpanzees allows “the local administration to have accurate information to make informed decisions to conserve Senegal’s biodiversity.”
Pruetz spends part of the year teaching at Texas State University, while his four research assistants and project manager, who are originally from nearby villages, continue to track the monkeys.
They keep track as Raffy hits a baobab fruit eight times, or note which arm he uses to do so — even though chimpanzees are normally left-handed.
But they also meticulously follow the chimpanzees’ friendships and social difficulties.
“When someone gets home from being with the chimps all day, you sit around the table and talk about what drama? What did Cy do today? What did Pistachio do today?” said Pruetz, who has images of three of the group’s deceased or missing chimpanzees tattooed on her arm.
Chimpanzees can live up to 50 years in the wild, and how their “relationships change” is just one of many interests for Pruetz.
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