What determines the speed at which birds fly?
The authors argue that only empirical measurements of flight speeds enable you to evaluate how general such aerodynamic rules really are. They used tracking radar measurements of the cruising speeds of migrating birds (collected by themselves and others) to do the analysis and provide the comprehensive dataset with the paper (e.g. this contains the flight speed of approximately one-third of all European bird species).
Their analysis reveals that the difference between the speed of small and large birds is not as great as expected; they suggest that this surprising re ...more