Dawn was broken by a morning screech across the savannah, followed by more screeches and the shaking of branches.
The rare chimpanzees – who normally live in hot, southeastern Senegal bush rather than forest – exist at the extreme edge of what is possible for their species.
Their unusual way of life provides clues to humans’ own evolutionary past, while their adaptation to temperatures in a warming world appears timely.
Soaking in pools, chilling in caves and even wielding spears: the 35 wild chimpanzees of the Fungoli community have adapted to the environment with behaviors that defy the traditional norms of their species.
Now, 25 years after beginning her pioneering research on savannah chimps, which had never before been habituated to observers, primatologist Jill Pruetz has more data.
The longevity of the study allows for a deep dive into the Fongoli community’s behavior, relationships, and how they learn from one generation to the next.
“Until they get used to observers we can follow them around and take data, we only know chimpanzees in the wild,” Pruetz told AFP reporters, who spent two days with her and her team tracking the primates in the bush.
Fongoli chimpanzees, which live in a 100-square-kilometer (40-square-mile) home range, are the only group of savanna chimpanzees in the region, but one that has been studied for years.
On a recent morning, AJ, Rafi, Diouf and an ambitious young pistachio were perched at the top of a baobab, picking a snack of fruit that they cracked open by hack-hack-hacking against the branches.
By shouting, or “pant-hooting” as their vocalizations are known, they communicate with other members nearby.
Pruetz and his team of Senegalese researchers follow the adult males of the group, which currently numbers 10, choosing one each day to track from dawn to dusk. However, women are not followed to make them more wary of predators.
A strict hierarchy of males extends from Psi, the alpha, down to Siberut, the oldest and lowest ranking despite his superior hunting skills.
Because social apes spend much of their time together, Pruetz is still able to observe females and their young.
It is the women who have proved the most important members of the tribe: they are the only non-human animals that systematically use tools to hunt.
It’s a behavior Pruetz and his researchers have observed nearly 600 times.
– ‘hottest region’ –
After clinging to spears, often with their teeth, females hunt bush babies during the rainy season and stalk small primates while taking shelter in tree holes.
With the heat index reaching 49 °C (120 °F) in hot weather, life in the savannah can be miserable.
Fongoli chimps “have to deal with the hottest areas we’ve ever studied chimps in” and “minimize energy expenditure” in dry weather, Pruetz said.
They are the only wild chimpanzees in the world that know how to dip and soak in natural pools. They additionally “use the caves to rest, because the caves are cold,” Pruetz told AFP.
The savannah woodlands that are home to Fongoli chimpanzees are similar to those inhabited by human ancestors some 6 or 7 million years ago.
By looking at chimpanzees, humans’ closest relatives, along with bonobos, perhaps we can “help confirm some hypotheses about how those really early hominins, or bipedal apes, behaved,” Pruetz said.
While the many adaptations of Fungoli chimpanzees mean they are “able to cope with high heat stress”, Pruetz said, “we are not sure if they can continue to do so with climate change”.
– gold rush –
Fongoli apes are members of a critically endangered subspecies of West African chimpanzees.
While they have traditionally co-existed with humans in their home range, a new threat has emerged: the gold rush that has led to an increase in both artisanal and industrial mining.
In the morning, the roar of grinding machines crushing rock from buckets of substrate could be heard before the fauna of the savanna began its daily chorus.
Fires burned at artisanal mine sites, where night guards watched the equipment.
Mines can cause water pollution, massive resource extraction and spread human disease to chimps.
Papa Ibnou Ndia, a wildlife researcher and professor at the Cheikh Anta Diop University in Dakar, said the study of the Fongoli chimpanzees “allows the local administration to get accurate information for the conservation of Senegal’s biodiversity”.
Pruetz spends part of the year teaching at Texas State University, while her four research assistants and project manager, who are originally from nearby villages, continue to track the monkeys.
They count as Rafi hits the baobab fruit eight times or note which hand he uses – although chimps are usually left-handed.
But they also carefully track the chimps’ friendships and social situations.
“When someone gets home from being out with the chimps all day, what drama do you sit around the dinner table talking about? What did Cy do today? What did Pistachio do today?” said Pruetz, who has images of three dead or missing members of the chimp group 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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