STUDY OF BIRD BEHAVIOUR 597 



new combinations, to form part, that is, of a reasoning process. An example will show what 

 is meant. A dog sees its master standing with a stick in his hand and calling in a loud and 

 angry voice ; it thereupon puts its tail between its legs and grovels or runs. Obviously the dog 

 is unable to form a verbal inference ; it cannot reason, " My master is angry, has a stick ; is, 

 therefore, going to beat me," for it has no word-imagery. But can it form a mental picture of 

 the stick playing on its back as last term in the process : master angry, stick ? If it can form 

 such an image, it is, according to the definition, capable of rational behaviour. If it cannot, if 

 it has learnt by painful experience merely to attach a meaning to certain proceedings on the 

 part of its master, to associate them with unpleasant consequences, to recognise them as ominous 

 without, however, being able to recall mentally the act of flagellation, then it is incapable 

 of rational behaviour ; it lacks the power of mental imagery without which no higher 

 mental life is possible. Its behaviour, in so far as not instinctive, is intelligent, and depends 

 always upon an object actually perceived, that is present to one or more of the organs of sense. 

 It is not here implied that a rational being would necessarily take the trouble to form a mental 

 image under the above circumstances, or even a verbal inference, which is only another form 

 of mental imagery. But the capacity to form the mental image would be there, and it is the 

 necessary condition of any process of reasoning that involves an object not actually perceived. 



Of the three kinds of behaviour, the instinctive is the most primitive. The life of the 

 lowest animals appears to be almost wholly, if not wholly, of this kind. But in the very 

 nature of things instinctive behaviour cannot suffice, for environment is not constant, and 

 hence the little round of instinctive acts that are adapted to a given environment become 

 useless or positively dangerous, when for some reason or other that environment changes, or the 

 creature moves into another. A stone-curlew, crouching instinctively on its native waste, 

 escapes detection owing to its concealing coloration. Turn the waste into green pasture, and the 

 bird's instinctive crouching causes its destruction. It is here that intelligence comes to the 

 rescue. If a species has sufficient innate plasticity to enable it to modify its instinctive 

 behaviour to suit new conditions, it survives ; if not, it perishes. And most have perished, if 

 our reading of the geological record is right. 



Kational behaviour succeeds intelligent. But at what point in the scale of animal life? 

 Has any animal below man the power to form a mental image ? This is still an open question. 

 A great mass of experimental evidence bearing on the point has in recent times been collected, 

 chiefly by American workers, but no convincing result has been reached. 1 There can be little 

 doubt that the behaviour of animals below man is, apart from a doubtful element of ration- 

 ality, mostly a complex of instinctive and intelligent, and it is by no means easy in given 

 cases to be sure where the one begins and the other ends. 



The chief questions that face the student of animal behaviour, and consequently of bird 

 behaviour, will be already apparent. Firstly, is this or that act instinctive, intelligent, or 

 rational ? For example, to what extent is the art of nest-building inherited, to what extent 

 acquired by experience ? Secondly, what is the origin of the three kinds of behaviour ? 

 Is rational behaviour evolved from intelligent, and this again from instinctive ? How did the 

 instinctive arise ? Is there, in short, continuity of development in animal behaviour, and what 

 is its origin? Finally, one might go further and ask, what is the relation between behaviour 

 and the associated conscious states, between nervous process and mental process, body and mind? 

 but this question of questions takes us outside the scope of our study. 



Such are the fundamental questions, and to answer them many subsidiary questions must 

 be put. A list of some of those which have reference to the study of bird behaviour will be 

 found below. To answer a few of them might well occupy the leisure of a lifetime. 



If to have in one's mind definite questions that call for answer, if knowing what to 



1 For the evidence, see Washburn, The Animal Mind (The Macmillan Co., K.Y.), and works there cited. 

 VOL. IV. 4 G 



