Fish-hunting chimpanzees have been found to enjoy termites as a seasonal treat

Fish-hunting chimpanzees have been found to enjoy termites as a seasonal treat

Famed scientist Jane Goodall’s discovery in 1960 that chimpanzees use tools to hunt termites revolutionized our understanding of these primates’ abilities—but we still don’t have crucial context to help us understand termite hunting and chimpanzee minds. Do chimpanzees hunt for seasonal food or try their luck?

Researchers from the University of California Santa Cruz (UCSC) and University College London (UCL) investigated the relationship between termite availability and chimpanzee hunting. They found that termites are more available early in the rainy season. Although other foods are abundant at that time, chimpanzees choose to hunt termites at that time.

“I think these results raise an interesting hypothesis about perceptual cognition in wild chimpanzees foraging,” said Dr Vicky Ouels, from the University of California, Calif., and senior author of the study. Frontiers in ecology and evolution. “Although we can never read chimpanzees’ minds, perhaps we can begin to get an idea of ​​their expectations of resource availability by analyzing instances in which they access termite mounds and investigate them for their suitability for hunting.”

Termites are a major source of nutrients for chimpanzees, but the chimpanzee species prefers to live deep in castle-like mounds. However, some termites will disperse to start a new colony elsewhere, leaving the mound via flight holes that chimpanzees exploit to hunt termites. In some places, chimpanzees hunt all year round, and in other places, hunting is seasonal.

Understanding termite availability is important for understanding variation in chimpanzees’ use of hunting tools. Does tool use differ between chimpanzee groups because of different opportunities, because of different needs, or because tool use is less likely to have been invented or conserved? To understand predators, we have to understand prey.

The scientists focused on the Isa Valley in Tanzania, which has very distinct wet and dry seasons. The researchers combined years of meteorological data and camera trap footage of 13 mounds to map termite dispersal and predation through time. They also conducted experiments on termite hunting in 14 mounds between 2018 and 2022, imitating chimpanzee tools and techniques.

“When I first visited Wadi Isa, I quickly learned that termites were much more difficult to hunt than I expected,” said Seth Phillips, UCSC, corresponding author. “It alerted me to the idea that effectively searching for termite prey may be more complex than people generally understand.”

Of 1,924 termite capture attempts, 363 termites were recovered. The scientists found that they were more likely to be able to extract termites as rainfall increased, until 200 mm of rain fell. Then the percentage of successful experiments decreased. Most termite mounds were most active between 50-200 mm of cumulative rainfall. Dispersal trips took place only during the rainy season and stopped almost completely after 400 mm of rain fell.

“We are currently reviewing camera footage of chimpanzee behaviors in these hills,” Phillips said. “We want to know how chimpanzees adapt their foraging behavior to seasonal changes. For example, do they inspect termite mounds immediately after rainfall after a long dry period? These data could say something interesting about their perception of foraging in relation to the use of Tools.

Chimpanzees were among the most frequently recorded predators at termite mounds during dispersal trips and often arrived carrying a tool. At this time of year in Wadi Isa, another food is available: chimpanzees use tools to hunt termites because they can, not because they need to.

Although some chimpanzee communities exploit termites throughout the year, including in the relatively nearby Gombe River, termite hunting there also peaks in the early rainy season. Some year-round hunters may benefit from softer soil or more effective tackle sets. It is unclear whether more sophisticated tools will allow continued exploitation of termite mounds in Wadi Isa, but initial tests suggest otherwise.

“Ultimately, we are human experiments trying to replicate chimpanzee behavior,” Phillips warned. “We should not, for example, be considered as effective at hunting for termites with these tools as chimpanzees. I expect that the opportunity for chimpanzees to hunt for termites in Wadi Isa is at least a little wider than it is for human searchers.”

This story has been lightly edited from the original version I published Frontier Science News.

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