New infrared camera footage shows rare western black crested gibbons swinging among tree branches in southwest China's Yunnan Province. According to research, the IQ of young gibbons is very high and throwing stones is a kind of survival skill training for them. Spotting them on the ground is rare, as they usually eat and live in the trees. Western black crested gibbons are under first-level national protection in China. Their population is increasing thanks to protection measures in recent years.