196 THE STORY OF THE BIRDS 



bill in the Charadriiformes also presents con- 

 siderable diversity in harmony with special 

 kinds of food and peculiar methods of obtain- 

 ing it ; in the Lariformes, however, there is 

 much greater uniformity, because these birds 

 all feed upon fish and similar prey. The Terns, 

 however, have the bill modified to seize their 

 prey by a plunge, whilst the type of bill is 

 most emphasised in the Skuas, which are, as 

 we have already seen, notorious robbers of 

 the food from the Gulls. Another group in 

 which the food is very uniform in character 

 is the Parrots, and as a consequence we do 

 not find much radical modification in the bill, 

 that organ being adapted to crush nuts, fruits, 

 and so on. 



We may now pass on to a brief notice of the 

 social, gregarious, or solitary instincts of Birds. 

 Even the most casual observer of birds cannot 

 fail to remark that these creatures vary a good 

 deal in their social instincts, either throughout 

 the year or more particularly at certain seasons. 

 As we find examples of each of these instincts in 

 almost every great group, no general rule can 

 well be laid down respecting them. Perhaps 

 the most widely prevailing of these instincts is 

 the social one. This may be partial ; that is to 



