NATURAL HISTORY OF SELBORKE. 141 



to me to be the effect of rivalry and emulation : and it 

 is to this spirit of jealousy that I chiefly attribute the equal 

 dispersion of birds in the spring over the face of the 

 country. 



Now as to the business of food : as these animals are 

 actuated by instinct to hunt for necessary food, they should 

 not, one would suppose, crowd together in pursuit of 

 sustenance at a time when it is most likely to fail ; yet 

 such associations do take place in hard weather chiefly, and 

 thicken as the severity increases. As some kind of self- 

 interest and self-defence is no doubt the motive for the 

 proceeding, may it not arise from the helplessness of their 

 state in such rigorous seasons; as men crowd together, 

 when under great calamities, though they know not why 1 

 Perhaps approximation may dispel some degree of cold ; 

 and a crowd may make each individual appear safer from 

 the ravages of birds of prey and other dangers. 



If I admire when I see how much congenerous birds love 

 to congregate, I am the more struck when I see incongruous 

 ones in such strict amity. If we do not much wonder to 

 see a flock of rooks usually attended by a train of daws, 

 yet it is strange that the former should so frequently have 

 a flight of starlings for their satellites. Is it because rooks 

 have a more discerning scent than their attendants, and can 

 lead them to spots more productive of food ? Anatomists 

 say that rooks, by reason of two large nerves which run 

 down between the eyes into the upper mandible, have a 

 more delicate feeling in their beaks than other round-billed 

 birds, and can grope for their meat when out of sight. 

 Perhaps, then, their associates attend them on the motive 

 of interest, as greyhounds wait on the motions of their 

 finders; and as lions are said to do on the yelpings of 

 jackals. Lapwings and starlings sometimes associate. 



