36 BRITISH LAND BIRDS. 



flocks, again taking flight together towards the 

 south as the cold season approaches. The peewits 

 and plovers also constantly remain in flocks or 

 families.^ 



Few birds are more gregarious than the rooks, 

 which we see at nightfall, 



" Ketiring from the downs, where all day long 

 They pick their scanty fare ; a black'ning train 

 Of loitering rooks thick urge their weary flight, 

 And seek the shelter of the grove." 



Their habits, in this respect, are so well known as 

 to need no comment. 



Fieldfares, again, which arrive in this country 

 in great flocks from the northern parts of the 

 continent in the beginning of the autumn, return, 

 in the same manner, to their native forests, where 

 they stud the huge fir-trees with their nests. It 

 would appear that with them, as with the rooks, 

 the sense of security occasions these associations, 

 as they have evident marks of keeping watch to 

 announce the approach of danger, and there are 

 few birds more difficult to get near to. 



The system of setting a watch to give the signal 

 of danger is adopted generally by all the grega- 

 rious races of birds. These sentinels station 

 themselves at some little distance from the main 



* Thompson. 



