Squirrel monkeys enjoy themselves outdoor at the Shangfangshan Forest Zoo in Suzhou, east China's Jiangsu Province, Aug. 13, 2018. (Xinhua/Hang Xingwei)

Squirrel monkeys enjoy themselves outdoor at the Shangfangshan Forest Zoo in Suzhou, east China's Jiangsu Province, Aug. 13, 2018. (Xinhua/Hang Xingwei)

Squirrel monkeys enjoy themselves outdoor at the Shangfangshan Forest Zoo in Suzhou, east China's Jiangsu Province, Aug. 13, 2018. (Xinhua/Hang Xingwei)

Squirrel monkeys enjoy themselves outdoor at the Shangfangshan Forest Zoo in Suzhou, east China's Jiangsu Province, Aug. 13, 2018. (Xinhua/Hang Xingwei)