Rainforest Chimps Dig Wells to Find Fresh, Filtered Water

While one female digs, other chimps wait patiently to drink.

Chimpanzee with her baby on the back
Musat / Getty Images

If you want fresh water, sometimes you have to dig for it yourself. That’s what rainforest chimpanzees have found in Uganda.

Researchers have followed a group of chimpanzees and found they have adapted to the limited water in their habitat by digging to find it.

Researchers studied a group of Eastern chimpanzees (Pan troglodytes schweinfurthii) which are classified as endangered by the International Union for Conservation of Nature (IUCN) Red List. The chimps face habitat loss from human encroachment for agriculture, roads, and mining, and have also seen their populations drop from poaching and disease.

Digging a small well to uncover clean water isn’t a very common behavior in the animal kingdom. According to researchers, only a few species have been observed doing it, and most live in arid or desert areas.

“So far it’s been documented in chimpanzees, baboons, some equid species, warthogs, and elephants, but even for these species it’s a rare behavior,” lead author Hella Peter, a biological anthropology Ph.D. student at the University of Kent in the United Kingdom, tells Treehugger.

“In chimpanzees, we only know about three other communities who dig wells, all of them living in dry, arid habitats.”

Unexpected Behavior

Peter and her colleagues were motivated to study the well-digging chimps by a random occurrence.

“Working with chimpanzees, they are one of the species that are smart enough to sometimes surprise you with the most unexpected behaviors, regardless of what you originally set out to study,” Peter says.

“This study was born out of one of those moments, with a young female chimp digging a well one day in 2015. We were curious to see how the others in the community would react, if they’d learn or not.” 

Onyofi was a young female new to the area. Like other adolescent chimps, she left the community where she was born and decided to make a home in the Waibira community in Uganda. She was immediately very skilled at digging for water, so it was likely that she grew up in a community where others did the same.

“We first spotted her digging in 2015—it was something we haven’t seen before in the community, and she seemed confident in what she was doing, probably having learned it in her natal group,” Peter says. “The other adult chimps also acted like it was new to them, leaning in close to watch her, sometimes even following her movements with their head, which supported our theory that well-digging is a new thing for Waibira.”

Onyofi would use her hands to dig small holes, wait for the water to filter in, then drink it. Once Onyofi was finished drinking, other chimps would move in and drink from the wells directly or use leaves, moss, or a combination of materials to sponge up water.

The findings were published in the journal Primates.

The Importance of Water

The researchers point out that some people might think getting water in a rainforest shouldn’t be difficult. But it appears that the first few months of the dry season cause challenges. Well-digging behavior was most commonly observed when rainfall was lower than average.

Also interesting, the wells were found not only in dry riverbeds, but also right next to flowing water. This suggests digging helps filter the water, removing debris that might be found in the open water.

“Water is an essential resource, even more so than food. Without it, animals face dehydration, increased stress levels, and for females, it can interfere with lactation as well. While the Waibira chimps live in a rainforest, during dry season they also have to find ways to get enough water,” Peter says.

“With climate change, the amount of rainfall an area receives can shift, and there is an increasing chance of extreme weather events like droughts, which means populations that previously had enough water now might have to adapt. We hope that studying already existing adaptations to water shortage can help us with future chimpanzee conservation efforts.”  

Learning to Dig

While other chimps seemed intrigued by what Onyofi was doing, only a few of the young ones and adult females tried copying what she did.

“The males do use the wells (and very politely wait their turn!), but don’t seem to be motivated to dig one for themselves,” Peter says. “We are hoping that the behavior will spread even more in the coming years, maybe infants learning it from their mothers, or the big males learning it from one of the young well-digging males.”

There could be several reasons the males don’t mimic the well-digging behavior.

“Chimps are very picky in what they learn and from who. Maybe for the adult males, Onyofi and the other adult females are not good enough teachers, being subordinate to males,” Peter says. “It could also be that digging a well for cleaner or different tasting water just isn’t worth it for them, but they seem to enjoy using the ones others have dug.”

Researchers hope that studying these adaptations that chimps already use to deal with water shortages might help with chimp conservation efforts.

“Waibira is the first group of rainforest chimps to show a behavior to access water that has previously only been seen in savannah living groups,” Peter says. “This tells us about how important water is as a resource, and also gives us some hope for the future: If chimpanzee communities know ways to deal with water shortage, they might be more resilient to climate change.”

View Article Sources
  1. Péter, Hella, et al. "Well-Digging in a Community of Forest-Living Wild East African Chimpanzees (Pan Troglodytes Schweinfurthii)." Primates, vol. 63, no. 4, 2022, pp. 355-364., doi:10.1007/s10329-022-00992-4

  2. Hart, A. "Eastern Chimpanzee." IUCN Red List of Threatened Species, 2016, doi:10.2305/iucn.uk.2016-2.rlts.t15937a17990187.en

  3. Hella Peter, a biological anthropology Ph.D. student at the University of Kent