XINING, Jan. 30 (Xinhua) -- The number of rare animal species has been growing steadily in Sanjiangyuan National Park as the area's environment keeps improving, according to an official report.

Sanjiangyuan, meaning the "sources of three rivers," is home to the headwaters of the Yangtze, Yellow and Lancang (Mekong) rivers. The national park, located in northwest China's Qinghai Province, is home to 270 species of wild land vertebrates, of which 69 are under state protection, according to a report released Tuesday by the Qinghai provincial government.

The report is based on an investigation launched in 2016 to determine the number and distribution of major wildlife species in the park.

It said researchers found 16 species under top national protection in the area, such as wild yak and snow leopard, and 35 species under Class Two national protection, including bharal and Tibetan gazelle.

The number of snow leopards in the national park ranges between about 400 to 700. They have appeared in a wider area and been spotted more frequently in recent years, according to the report.

China is setting up a national park system and has piloted 10 national parks across the country to protect the natural environment and endangered species, with Sanjiangyuan National Park the first.

The Sanjiangyuan National Park, under construction since 2016, is set to open in 2020.