Antelopes are seen at Nairobi National Park in Nairobi, capital of Kenya, Dec. 22, 2019. Located in the capital of Kenya, Nairobi National Park covers an area of 117 square kilometers and is home to 100 kinds of mammals including giraffes, lions and antelopes. The park attracts numerous tourists during the Christmas holidays. (Xinhua/Wang Teng)

A giraffe feeds at Nairobi National Park in Nairobi, capital of Kenya, Dec. 22, 2019. Located in the capital of Kenya, Nairobi National Park covers an area of 117 square kilometers and is home to 100 kinds of mammals including giraffes, lions and antelopes. The park attracts numerous tourists during the Christmas holidays. (Xinhua/Wang Teng)

Tourists travel at Nairobi National Park in Nairobi, capital of Kenya, Dec. 22, 2019. Located in the capital of Kenya, Nairobi National Park covers an area of 117 square kilometers and is home to 100 kinds of mammals including giraffes, lions and antelopes. The park attracts numerous tourists during the Christmas holidays. (Xinhua/Wang Teng)

Tourists travel at Nairobi National Park in Nairobi, capital of Kenya, Dec. 22, 2019. Located in the capital of Kenya, Nairobi National Park covers an area of 117 square kilometers and is home to 100 kinds of mammals including giraffes, lions and antelopes. The park attracts numerous tourists during the Christmas holidays. (Xinhua/Wang Teng)

A bird stands at Nairobi National Park in Nairobi, capital of Kenya, Dec. 22, 2019. Located in the capital of Kenya, Nairobi National Park covers an area of 117 square kilometers and is home to 100 kinds of mammals including giraffes, lions and antelopes. The park attracts numerous tourists during the Christmas holidays. (Xinhua/Wang Teng)

Tourists watch giraffes at Nairobi National Park in Nairobi, capital of Kenya, Dec. 22, 2019. Located in the capital of Kenya, Nairobi National Park covers an area of 117 square kilometers and is home to 100 kinds of mammals including giraffes, lions and antelopes. The park attracts numerous tourists during the Christmas holidays. (Xinhua/Wang Teng)

Antelopes are seen at Nairobi National Park in Nairobi, capital of Kenya, Dec. 22, 2019. Located in the capital of Kenya, Nairobi National Park covers an area of 117 square kilometers and is home to 100 kinds of mammals including giraffes, lions and antelopes. The park attracts numerous tourists during the Christmas holidays. (Xinhua/Wang Teng)

Tourists are seen at Nairobi National Park in Nairobi, capital of Kenya, Dec. 22, 2019. Located in the capital of Kenya, Nairobi National Park covers an area of 117 square kilometers and is home to 100 kinds of mammals including giraffes, lions and antelopes. The park attracts numerous tourists during the Christmas holidays. (Xinhua/Wang Teng)

Tourists travel at Nairobi National Park in Nairobi, capital of Kenya, Dec. 22, 2019. Located in the capital of Kenya, Nairobi National Park covers an area of 117 square kilometers and is home to 100 kinds of mammals including giraffes, lions and antelopes. The park attracts numerous tourists during the Christmas holidays. (Xinhua/Wang Teng)

Tourists watch giraffes at Nairobi National Park in Nairobi, capital of Kenya, Dec. 22, 2019. Located in the capital of Kenya, Nairobi National Park covers an area of 117 square kilometers and is home to 100 kinds of mammals including giraffes, lions and antelopes. The park attracts numerous tourists during the Christmas holidays. (Xinhua/Wang Teng)