Carduelis chloris
Bird experts suspected that the immigration of birds from Europe to China was posing a threat to the local ecosystem.
Carduelis chloris is originally a European species. Those birds appeared in China more than 10 years ago as stragglers, passing migrants or winter migrants. However, they have become the breeding and resident birds in the country in recent years.
"At least 20 species of birds are migrating from Europe eastward to China and other countries," said Ma Ming, a researcher from Xinjiang Institute of Geography and Ecology (XIEG), Chinese Academy of Sciences (CAS). He added that the living space for those birds expands at a speed of 70-80 kilometers a year east bound.
What made the bird travel so far to reside in a foreign land? Besides other reasons, researchers summed up the reasons as the global warming, the overuse of fertilizer and industrial pollution. The warmer climate made it possible for passing migrant bird to reside, and the pollution and fertilizer helped kill its natural enemy.
Ma said Columba oenas,Steptopelia senegalensis and dozens of other species of birds were found almost every year as new migrants in the areas east to their original habitats.
A direct consequence of this expansion will be the decrease, and even distinction of some local species, warned bird experts.
