90 BIRDS IN TOWN AND VILLAGE 



ducks, and waders, it becomes plain that it is not 

 assignable to community of descent, but has origin- 

 ated independently all over the globe, in a vast 

 number of species. Something of the beginnings 

 and progressive development of this instinct may be 

 learnt, I think, by noticing the behaviour of various 

 passerine birds in the presence of danger to their 

 nests and young. Their actions and cries show that 

 they are greatly agitated, and in a majority of species 

 the parent bird flits and flutters round the intruder, 

 uttering sounds of distress. Frequently the bird 

 exhibits its agitation not only by these cries and 

 restless motions, but by the drooping of the wings 

 and tail — ^the action observed in a bird when hurt 

 or sick or oppressed with heat. These languishing 

 signs are common to a great many species after the 

 young have been hatched, the period when the 

 parental solicitude is most intense. In several 

 species which I have observed in South America 

 the languishing is more marked. There are no 

 sorrowful cries and restless movements ; the bird 

 sits with hanging wings and tail, gasping for breath 

 with open bill — ^in appearance a greatly suffering 

 bird. In some cases of this description the bird, 

 if it moves at all, hops or flutters from a higher to a 

 lower branch, and, as if sick or wounded, seems 

 about to sink to the ground. In still others the 

 bird actually does drop to the ground, then, feebly 



