Natural History 415 



of the trumpeter in driving their fellows home in the evening must 

 be regarded as similar in its origin to that of the male swift, when 

 he hunts his mate back to the nest, and of the sand-martin I ob- 

 served chasing the females of the colony to their burrows. In a 

 lesser way it may be seen in any flock of birds ; they move about 

 in such an orderly manner, springing, as it appears to us, simul- 

 taneously into the air, going in a certain direction, settling here 

 or there to feed, presently going to another distant feeding- 

 ground or alighting to rest or sing on trees and bushes, as to pro- 

 duce the idea of a single mind. But the flock is not a machine ; the 

 minds are many ; one bird gives the signal the one who is a little 

 better in his keener senses and quicker intelligence than his com- 

 panions ; his slightest sound, his least movement is heard and seen 

 and understood and is instantly and simultaneously acted upon." 



Interrelations 



Many curious associations are formed by birds during the 

 breeding season. The Puffin is quite capable of making a hole for 

 itself in the face of some precipitous slope, but frequently it pre- 

 fers to appropriate a rabbit's burrow, ejecting the rightful owner 

 without ceremony. Other burrowing birds are often more ac- 

 commodating, for the Burrowing Owls of America live amicably 

 with the Prairie Dogs whose retreats they so often share, and in 

 New Zealand the same holes are shared by Petrels and Tuatera 

 Lizards without apparent friction. In cases of this kind, however, 

 it is always possible that the partnership has other advantages- 

 such as common defence or watchfulness than the mere saving 

 of labour on the one hand or on the other : there is the curious case, 

 for instance, of the Ruddy Kingfisher of Borneo, which makes its 

 nest in the hive of a peculiarly vicious kind of bee ! 



8 

 Our Common Birds 



The late Professor Newton has an interesting passage in 

 which he shows that we can tell which birds were most familiar 



