Critically endangered golden-bellied capuchins (Sapajus xanthosternos) are more widespread than researchers previously thought, and stone tools might be the secret to their success.
Although golden-bellied capuchins are usually found in the humid Atlantic Forest of eastern Brazil, at the State University of Montes Claros in Brazil found a population of the monkeys outside the forest several years ago. 鈥淭his stayed in my mind,鈥� he says. So he and his colleagues began studying the species in more detail to fully understand its geographical range.
They have now discovered golden-bellied capuchins are present at several sites in the dry forest south of their usual habitat. This has increased the monkeys鈥� known geographical range by almost 20,000 square kilometres. 鈥淔or an endangered species, any expansion of its limits, no matter how small, is very important for its conservation,鈥� says Martins.
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The survey work also revealed something else 鈥� evidence S. xanthosternos populations in the dry forest use stone tools to split open tough palm tree fruits. That is a significant discovery because the species doesn鈥檛 seem to use stone tools in the Atlantic Forest, even when it has access to suitable stones.
This makes Martins and his colleagues suspect stone tools allowed the monkeys to move into new territory. Easily accessible food is harder to find in the dry forest, so the capuchins may only be able to survive there because tools allow them to eat the less accessible flesh of palm tree fruits. The conclusion invites comparisons between the capuchins and our human ancestors, who may also have relied on tools and technology to expand into new environments.
at Nanyang Technological University in Singapore says Martins and his colleagues still have work to do to strengthen their idea. 鈥淒id S. xanthosternos colonise the drier habitats and start using tools? Were they already there [using tools], and then the habitat dried?鈥�
But , an independent researcher in the UK, thinks the circumstantial evidence is enough to support the idea. He says led by at the University of California, Los Angeles 鈥� who was also involved in the new analysis 鈥� suggests capuchins have been living in the Atlantic Forest for several million years but only moved into the drier forest environments to the south and west within the last 750,000 years. 鈥淚t is a reasonable hypothesis that the expansion was made possible by stone tools to exploit the tougher foods found in those drier places,鈥� he says. Lynch and her colleagues made a similar suggestion a decade ago 鈥� and the new study provides greater support.
Whether this behavioural flexibility will help the endangered species cope with ongoing habitat loss is unknown. 鈥淭he kind of work in the new study is vital for understanding how the two primates 鈥� us and [golden-bellied] capuchins 鈥� can or will adapt to each other,鈥� says Haslam.
International Journal of Primatology
