A gibbon is seen at Pairi Daiza zoo in Brugelette, Belgium, on Aug. 9, 2019. Pairi Daiza is a large animal theme park in Brugelette in west Belgium's Hainaut province. (Xinhua/Zhang Cheng)

White rhinoceroses are seen at Pairi Daiza zoo in Brugelette, Belgium, on Aug. 9, 2019. Pairi Daiza is a large animal theme park in Brugelette in west Belgium's Hainaut province. (Xinhua/Zhang Cheng)

A fallow deer is seen at Pairi Daiza zoo in Brugelette, Belgium, on Aug. 9, 2019. Pairi Daiza is a large animal theme park in Brugelette in west Belgium's Hainaut province. (Xinhua/Zhang Cheng)

A white rhinoceros is seen at Pairi Daiza zoo in Brugelette, Belgium, on Aug. 9, 2019. Pairi Daiza is a large animal theme park in Brugelette in west Belgium's Hainaut province. (Xinhua/Zhang Cheng)

A porcupine is seen at Pairi Daiza zoo in Brugelette, Belgium, on Aug. 9, 2019. Pairi Daiza is a large animal theme park in Brugelette in west Belgium's Hainaut province. (Xinhua/Zhang Cheng)

An alpaca is seen at Pairi Daiza zoo in Brugelette, Belgium, on Aug. 9, 2019. Pairi Daiza is a large animal theme park in Brugelette in west Belgium's Hainaut province. (Xinhua/Zhang Cheng)

Two camels rest at Pairi Daiza zoo in Brugelette, Belgium, on Aug. 9, 2019. Pairi Daiza is a large animal theme park in Brugelette in west Belgium's Hainaut province. (Xinhua/Zhang Cheng)

A hippopotamus waits to be fed at Pairi Daiza zoo in Brugelette, Belgium, on Aug. 9, 2019. Pairi Daiza is a large animal theme park in Brugelette in west Belgium's Hainaut province. (Xinhua/Zhang Cheng)

An alpaca is seen at Pairi Daiza zoo in Brugelette, Belgium, on Aug. 9, 2019. Pairi Daiza is a large animal theme park in Brugelette in west Belgium's Hainaut province. (Xinhua/Zhang Cheng)

A red river hog sleeps at Pairi Daiza zoo in Brugelette, Belgium, on Aug. 9, 2019. Pairi Daiza is a large animal theme park in Brugelette in west Belgium's Hainaut province. (Xinhua/Zhang Cheng)

An Asian black bear is seen at Pairi Daiza zoo in Brugelette, Belgium, on Aug. 9, 2019. Pairi Daiza is a large animal theme park in Brugelette in west Belgium's Hainaut province. (Xinhua/Zhang Cheng)

A blue crane is seen at Pairi Daiza zoo in Brugelette, Belgium, on Aug. 9, 2019. Pairi Daiza is a large animal theme park in Brugelette in west Belgium's Hainaut province. (Xinhua/Zhang Cheng)

A shoebill is seen at Pairi Daiza zoo in Brugelette, Belgium, on Aug. 9, 2019. Pairi Daiza is a large animal theme park in Brugelette in west Belgium's Hainaut province. (Xinhua/Zhang Cheng)

A white tiger is seen at Pairi Daiza zoo in Brugelette, Belgium, on Aug. 9, 2019. Pairi Daiza is a large animal theme park in Brugelette in west Belgium's Hainaut province. (Xinhua/Zhang Cheng)