NOTICEABLE INCIDENTS 77 



discover at the earliest opportunity the approach of 

 an enemy. 



There are times when birds which sing practically 

 throughout the year, such as the starling and robin, 

 abandon their songs. Such an occasion is observable 

 when their young are nearly ready to quit the nest. 

 Then these birds will sing at early morning and late 

 evening, before and after the labour of the day the 

 supplying of the wants of their young has been 

 performed ; but when the young leave the nest, and 

 parents are occupied all day in obtaining food for 

 them, the songs are quite abandoned, from the very 

 simple cause that the birds have no time for singing. 

 How can the robin, hunting everywhere for insects 

 and worms, waste a moment when his expectant 

 young demand his constant care ; or how would it 

 be possible for a starling, which, at the same period, 

 may often be seen panting from fatigue (especially 

 on a hot, dry day), to sing his usually long and noisy 

 phrases ? These birds, and others in like circum- 

 stances, do not then sing, because they are either 

 seeking food for their young, or are intently watching 

 lest enemies approach. In either event they have 

 not the necessary leisure in which to practise song. 

 I suggest that a want of leisure may have been a 

 potent cause of the lack of individual variation of 



