Abstract: Three species of birds,Pycnonotus sinensis Gmelin,Acridotheres cristatellus Linne and Turdus merula in Zhengzhou City were surveyed during 11consecutive years,it was found that the niche of three kind of Oriental realm birds moves towards north.They moved from the Dabie Mountain area to Zhengzhou lied in the south bank of Yellow River and became resident birds here,and then flew across Yellow River in 2002.Population is beyond the limits of niche space.The main factors of widening of the niche are the limit...