AREA DETERMINED HV HABIT 205 



more frequently than the other two, and in the 

 course of time heroines the sole highway to and 

 from the nest. Suppose now that, when the 

 young are hatched, I cut away the foliage from 

 the hush on the opposite side from that on 

 which the bird customarily enters, and by so 

 doing lenve the nest exposed, what is the result? 

 The female arrives with food, threads her way 

 through the bush, and, when beside the nest, 

 pauses as if aware that some change had taken 

 place, and then flies away through the new 

 opening. In a short time she returns, flits from 

 twig to twig on the outskirts of the bush, 

 and comes upon the new opening there she 

 hesitates. But though the nest is in full view 

 and within a few inches of her perch, and though 

 the young stretch out their necks, yet so strong 

 is the former habit that she is compelled to 

 return to the opposite side and approach the 

 nest by the usual circuitous route before she 

 distributes the food amongst her offspring. 



Let us see how far this law of habit 

 formation may have been effective in defining 

 the extent of the area occupied. When a male 

 Warbler arrives at its destination in the spring 

 it seeks out a suitable environment, and, having 

 found a place unoccupied by any other male, 

 settles in it and remains there its behaviour 

 up to this point being determined by racial 

 preparation. After the fatigue of the journey 

 its movements are at first sluggish ; hunger, 

 however, asserts itself and a search is made for 

 food ; wandering away from the position in 



