(ECNS) -- Temperatures in Pinglu, Shanxi Province have dropped to below zero degrees Celsius due to the cold air.
In the Sanwan section of the Yellow River wetland, where whooper swans get together, the timeline of their northward migration been delayed.
All whooper swans that relocate here for winter used to move north at the end of February annually. But this year, more than 100 whooper swans have yet to do so due to the lower temperatures.
Pinglu Yellow River Wetland is one of the three major wintering habitats of wild whooper swans in China.
From the end of October to the end of February, thousands of whooper swans overwinter here.