78 THE STUDY OF ANIMAL LIFE CHAP. 



birds." They post sentries, send scouts, have many 

 friends and few enemies, and are very intelligent. So it 

 is also with parrots. ; The members of each band re- 

 main faithfully attached to each other, and they share 

 in common good or bad luck." They feed together, fly 

 together, rest together ; they send scouts and post sen- 

 tinels ; they find protection and pleasure in combination. 

 Like the cranes, they are very intelligent, and safe from 

 most enemies except man. 



On the other hand, some of the most successful carni- 

 vores, e.g. wolves, hunt in packs, and not a few birds of 

 prey (some eagles, kites, vultures) unite to destroy their 

 quarry. Combination for defence has its counterpart in 

 combination for attack. In both cases the collective 

 action is often associated with the custom of posting 

 sentinels, who warn the rest, or of sending scouts to 

 reconnoitre. Peculiarly interesting are those cases in 

 which the relatively weak unite to attack the strong ; 

 thus a few kites will rob an eagle, and wagtails will perse- 

 cute a sparrow-hawk. Kropotkin has noticed how the 

 aquatic birds w r hich crowd on the shores of lakes and 

 seas often combine to drive off intruding birds of prey. 

 " In the face of an exuberant life, the ideally armed 

 robber has to be satisfied with the off-fall of that life." 



Among many animals there is co-operation in labour, 

 as well as combination for attack or defence. Brehm 

 relates that baboons and other monkeys act in thorough 

 concert in plundering expeditions, sending scouts, post- 

 ing sentinels, and even forming a long chain for the 

 transport of the spoil. It is said that several Hamadryad 

 baboons will unite to turn over a large stone, sharing the 

 booty found underneath. When the Brazilian kite has 

 seized a prey too large for it to carry, it summons its 

 friends ; and Kropotkin cites a remarkable case in which 

 an eagle called others to the carcase. Pelicans fish 

 together in great companies, forming a wide half-circle 

 facing the shore and catching the fish thus enclosed. 

 Burial beetles unite to bury the dead mouse or bird in 

 which the eggs are laid, and the dung-beetles help one 

 another in rolling balls of food. But of all cases of com- 



