Millions of animals cross the Mara River from Tanzania into

Wildebeests wade across the Mara River in Kenya's Masai Mara National Park on July 26, 2015. (Xinhua/Tian Guangyu)

Wildebeests wade across the Mara River in Kenya's Masai Mara National Park on July 26, 2015. (Xinhua/Tian Guangyu)

Wildebeests wade across the Mara River in Kenya's Masai Mara National Park on July 26, 2015. (Xinhua/Tian Guangyu)

Wildebeests eat grass after wading across the Mara River in Kenya's Masai Mara National Park on July 26, 2015. (Xinhua/Tian Guangyu)