Tourists look at a sea lion in Ljubljana Zoo in Ljubljana, Slovenia, Aug. 11, 2020. Tourists gradually return to Ljubljana Zoo, which was closed for a while due to the COVID-19 pandemic and reopened in late April. (Xinhua/Peng Lijun)

Tourists look at lions in Ljubljana Zoo in Ljubljana, Slovenia, Aug. 11, 2020. Tourists gradually return to Ljubljana Zoo, which was closed for a while due to the COVID-19 pandemic and reopened in late April. (Photo by Zeljko Stevanic/Xinhua)

A breeder feeds a red panda in Ljubljana Zoo in Ljubljana, Slovenia, Aug. 11, 2020. Tourists gradually return to Ljubljana Zoo, which was closed for a while due to the COVID-19 pandemic and reopened in late April. (Xinhua/Peng Lijun)

A child feeds a red panda in the Ljubljana Zoo in Ljubljana, Slovenia, Aug. 11, 2020. Tourists gradually return to Ljubljana Zoo, which was closed for a while due to the COVID-19 pandemic and reopened in late April. (Photo by Zeljko Stevanic/Xinhua)

Tourists look at an alpaca in Ljubljana Zoo in Ljubljana, Slovenia, Aug. 11, 2020. Tourists gradually return to Ljubljana Zoo, which was closed for a while due to the COVID-19 pandemic and reopened in late April. (Photo by Zeljko Stevanic/Xinhua)

Tourists look at lions in Ljubljana Zoo in Ljubljana, Slovenia, Aug. 11, 2020. Tourists gradually return to Ljubljana Zoo, which was closed for a while due to the COVID-19 pandemic and reopened in late April. (Photo by Zeljko Stevanic/Xinhua)