A medium-to-large macaque of Southeast Asian rainforests (Peninsular Malaysia, Sumatra, Borneo). Named for its short, curved, pig-like tail (~13–25 cm). Males weigh up to 15 kg, females ~6–8 kg, exhibiting marked sexual dimorphism. Pelage is olive-brown dorsally and lighter below, with a distinctive dark flat crown patch. They are semi-terrestrial, foraging both on the ground and in trees in primary and secondary lowland forests. Their diet is omnivorous: fruits, seeds, insects, crops, and small animals. Social organization consists of large multi-male groups. In parts of Malaysia and southern Thailand, they have been traditionally trained by humans to harvest coconuts from palm trees—a unique cultural practice. Gestation lasts ~170 days with a single infant. They are used in HIV/SIV research because they are susceptible to certain SIV strains and develop AIDS-like disease. Lifespan is ~26 years. Classified as Vulnerable by IUCN due to rapid habitat loss from palm oil plantations and logging, as well as capture for the pet trade.