File photo taken on July 23, 2016 shows two wildebeests battling with each other at the Maasai Mara National Reserve, Kenya. The International Day for Biological Diversity falls on May 22. (Xinhua/Pan Siwei)

An impala is seen at Nairobi National Park in Nairobi, capital of Kenya, May 19, 2021. The International Day for Biological Diversity falls on May 22. (Xinhua/Dong Jianghui)

A lion is seen at Nairobi National Park in Nairobi, capital of Kenya, May 19, 2021. The International Day for Biological Diversity falls on May 22. (Xinhua/Long Lei)

An ostrich is seen at Nairobi National Park in Nairobi, capital of Kenya, May 19, 2021. The International Day for Biological Diversity falls on May 22. (Xinhua/Long Lei)

Two zebras are seen at Nairobi National Park in Nairobi, capital of Kenya, May 19, 2021. The International Day for Biological Diversity falls on May 22. (Xinhua/Long Lei)

Hippos are seen in the water at Nairobi National Park in Nairobi, capital of Kenya, May 19, 2021. The International Day for Biological Diversity falls on May 22. (Xinhua/Long Lei)

Gazelles are seen at Nairobi National Park in Nairobi, capital of Kenya, May 19, 2021. The International Day for Biological Diversity falls on May 22. (Xinhua/Long Lei)

Antelopes are seen at Nairobi National Park in Nairobi, capital of Kenya, May 19, 2021. The International Day for Biological Diversity falls on May 22. (Xinhua/Dong Jianghui)