2i2 THE POPULAR SCIENCE MONTHLY 



Fig. 3. Platoon Flock Formation, which is seldom observed ; only the end 

 birds can see towards the side. The field of view becomes more obscured as the 

 number of birds increase. Non-protective. 



The influence of every bird in the flock will affect the flight direc- 

 tion of the flying flock to some extent, yet they each produce their re- 

 action, although perhaps not proportionately. It is probable that the 

 birds in the front of the main part of the flock affect the direction 

 greatest. 



avekaging of the errors of flight due to unequal wlng 



Power of Birds 



It is a well-known fact that when man is lost on a prairie or in a 

 snowstorm he will often travel in a circle. The reason for this is that 

 there is a small constant deviation of his course to the right or to the 

 left. Small as this deviation may be, it is certain to throw him com- 

 pletely off his bearings, and not infrequently results in circling with 

 fatal results. It is possible that a bird is subject to a similar deviation 

 of its course, owing to the inevitable production of a curved flight path 

 in case one wing of the bird is stronger than the other, the effect being 

 similar to a man in a boat pulling at the right oar more powerfully than 

 the left. Now the error of individual birds caused by a constant devia- 

 tion of path due to unequal wing power, as well as the error due to mis- 

 taken "bearings," would be corrected if the errors of the individual 

 birds in the flock are averaged while in flight by mutual reaction. 

 Fig. 2, A, is meant to illustrate these deviations due to unequal wing 

 strength, or to some similar cause, when single birds are proceeding, 

 for example, from the mainland to a far distant island destination D 

 (Fig. 2), and Fig. 2, B, the result when the birds are flying in a flock 

 and when these deviations are averaged. It is of course evident that the 

 averaged deviations might give a flight direction that is not exactly the 

 right one, and a flock of birds might fly in a wrong direction if much 

 confused. This is exactly what takes place; for occasionally flocks of 

 geese and other species of birds have been known to become completely 

 confused in a fog or during a stormy night. It is a very common occur- 

 rence for birds that are alone to become lost, as shown by the fact that 

 so frequently single land birds alight, utterly confused, on vessels far 

 out at sea. 



The averaging of the errors of the direction of flight of the indi- 

 viduals is of course subconsciously done by birds and is quite automatic. 



The principle of mutual reaction and its advantageous effect may be 

 advanced as a reason for the massing of birds into flocks prior to the 

 migratory journey, for if it is true that the flock formation has proved 



