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CHONGQING -- An increasing number of Chinese mergansers, an endangered bird species under state protection, have been spotted in China over the past three years, a survey showed Tuesday.

Bird-watching associations spotted a total of 1,084 Chinese mergansers across the country in the winter of 2016, according to a national survey released by the Chinese Bird Watching Societies Network in Chongqing municipality.

The figure was 634 and 441 in winters of 2015 and 2014 respectively, the survey said.

The increased sightings could be due to better public awareness on protecting the species and improved environment.

However, human activities such as illegal fishing and sand mining still pose a risk to their winter habitats.

"The species is very picky about the water environment. The survey can also be used to monitor water quality," said He Fenqi, an ornithology expert with Institute of Zoology, Chinese Academy of Sciences.

For example, more than ten years ago they mainly lived in rivers and clear creeks. Now they are often spotted in areas surrounding reservoirs. "This is the result of river degradation," He said.

Chinese mergansers are dubbed as "giant pandas of birds," with Russia's far east and northeast China their major reproduction bases.