ROOK. 145 



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 in- 

 creases. 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? 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. 



LETTER XII. To THE HON. DAINES BARRINGTON. 

 DEAR SIR, Selborne, March 9, 1772. 



As a gentleman and myself were walking on the fourth of last 

 November round the sea-banks at Newhaven, near the mouth of 

 the Lewes river, in pursuit of natural knowledge, we were sur- 

 prised to see three house-swallows gliding very swiftly by us. 



L 



