Before revision:  Yet the spatial correlations of such fluctuations  have a range as wide as the entire group : the speed change of a bird influences and is influenced by that of birds on the other side of the flock.
After revision:  Yet the spatial correlations of such fluctuations are scale-free, namely they have a range as wide as the entire group : the speed change of a bird influences and is influenced by that of birds on the other side of the flock.