Chimpanzees keep throwing rocks at same trees for a decade, scientists probe why

In the remote savanna-woodlands of Guinea-Bissau, scientists are investigating a strange chimpanzee behaviour that has persisted for more than a decade. Wild western chimpanzees repeatedly collect rocks and hurl them at the same trees, creating piles of stones and leaving visible scars on the trunks. Known as accumulative stone throwing, the behaviour is particularly associated with adult males and often occurs alongside loud vocalisations called pant-hoots and rhythmic strikes against tree trunks. Researchers believe these unusual sites could play a role in chimpanzee communication, territorial displays or social behaviour. However, the exact purpose remains unclear. By studying the trees, stones, sounds and chimpanzees involved, scientists hope to determine why these animals repeatedly return to the same locations and what the behaviour means.Why are chimpanzees throwing rocks at the same treesThe behaviour is remarkably specific. Rather than randomly throwing stones, the chimpanzees repeatedly target particular trees, often returning to the same locations over many years. In a recent report for The Conversation, researchers Robyn Nakano and Ammie Kalan described their expedition...