Army ants are not passive prey. A single Dorylus colony can weigh forty kilograms and contain millions of soldiers whose mandibles are built to hold. When a chimpanzee pushes a stick into a nest entrance, the colony responds immediately, recruiting more defenders as the disturbance continues. The longer a chimp stays at the nest, the worse it gets. Bites accumulate. The pressure mounts. At some point, even the most determined animal has to back off and shake the ants from its body before it can try again.
This is the adversarial context in which chimpanzees across Africa have developed what researchers call ant-dipping: the use of stick tools to harvest army ants, load them onto the stick, and pull them off with the free hand before eating. The technique varies across populations. Some communities use the pull-through method, sliding the loaded tool through a cupped hand. Others bring the stick directly to the mouth. Some use long tools; some use short
ones. Some communities in forest sites use a digging stick to widen the nest entrance before inserting the dipping tool, turning it into a two-stage tool set. A few populations, notably the Pan troglodytes of Taï Forest in Côte d’Ivoire, don’t use tools at all for certain ant species, simply grabbing brood by hand.
What’s driving all this variation? Ecology, culture, or some combination? That question is harder to answer than it sounds, because almost all the detailed work on ant-dipping has been done in forest habitats. Savanna populations have been underexamined. And chimpanzees are the only non-human ape that lives in open, hot, seasonally dry savannas at all — the kind of landscape that early hominins also occupied. If you want to understand what tool-using behavior looks like under those ecological pressures, savanna chimps are the only comparison available.
A study published in Scientific Reports1 in 2026, led by Andreu Sánchez-Megías and R. Adriana Hernandez-Aguilar at the University of Barcelona and the Jane Goodall Institute Spain, provides the first detailed account of ant-dipping in a savanna population. The site is Dindefelo, a community nature reserve in southeastern Senegal, covering about 140 square kilometers along the Guinea border. The climate is strongly seasonal, dry for roughly six months, with a mean annual temperature around 28.5°C. Evergreen vegetation — the moist, sheltered habitat army ants require — makes up less than twelve and a half percent of the landscape. Ants are scarce there. One of the lowest densities reported for the genus anywhere on the continent.
