38 BIRD LIFE GLIMPSES 



but I think it is, generally, one of many possible 

 ones which may all be expressed by the same note, 

 such note being the outcome, not of a definite 

 idea, but of a certain state of feeling. Surprise, for 

 instance, may be either a glad surprise or a fearful 

 surprise, and very varied acts spring from either 

 joy or fear. With ourselves definite ideas have 

 become greatly developed ; but animals may live, 

 rather, in a world of emotions, which would then 

 be much more a cause of their actions, and, con- 

 sequently, of the cries which accompanied them, 

 than the various ideas appertaining to each. Be- 

 cause, for instance, a rabbit stamps with its hind 

 feet when alarmed, and other rabbits profit by its 

 doing so, why need this be done as a signal, which 

 would involve a conscious design ? Is it not more 

 likely that the stamp is merely the reaction to 

 some sudden, strong emotion, which need not always 

 be that of fear ? If rabbits stamp, sometimes, in 

 sport and frolic — as I think they do — this cannot 

 be a signal, and therefore we ought not to assume 

 that it is, when it has the appearance, or produces 

 the eflFect, of one. All we can say, as it seems 

 to me, is that excitement produces a certain 

 muscular movement, which, according to the class 

 of excitement to which it belongs, may mean or 

 express either one thing or another. Such a 

 movement, or such a cry, is like the bang of a 

 gun, which may have been fired either as a salute 

 or with deadly intent. However, if the nightjar's 

 nineteen notes really express nineteen definite ideas 

 in the bird's mind, I can only confess that I have 

 not discovered what these are. Some of the sounds, 



