2o6 Wild Birds 



was undetermined. Each sign represents a visit to the nest 

 at which food was usually served. 



| Female RR RRLBRRRRRB 

 July 27th. Third day of ob- I ^ ~ ^ L R 



servation-6^ hours. RBRRRRRRRR _ RR 



B RRR -- RR 



{ Female LB B LB B BB 

 July 28th. Fourth day of ob- J 



servation 4 hours. | Male RRRRRRRRRRRRR 



RRR 



For the fourth day I have no record of the female approach- 

 ing by the right side, and no record of the male coming in any 

 other way. On the two following days the female did not 

 appear, and, as I had reason to believe, was engaged in building 

 a new nest. The male at this period always approached his 

 nest in the habitual manner. Now whether the male bird had 

 formed this habit shortly after the nest was built or shortly 

 after the nesting bough was removed is of little consequence. 

 At all events a definite mode of behavior had developed in a 

 short space of time. On the fourth day the young had to be 

 brooded often, owing to the heat, which accounts for the ap- 

 parent inactivity of the female in providing food. 



Birds form definite habits in the manner of approach to the 

 nest, entering on a certain side, or flying to a certain twig, 

 following the path suggested in the first instance by convenience 

 or dictated by caution. As we have already seen (in Chapter 

 XI.), the habit may arise at the very beginning of nest- 

 building. A pair of Red-eyed Vireos with whom I spent parts 

 of three days followed a definite course in approach with sur- 

 prising regularity. They would fly to the main branch, hop 

 along toward the fork in which the nest was suspended, and 

 finally perch on a small convenient twig just over their young. 

 Out of sixty recorded visits they deviated from this habitual 

 method but three times, and then only before they had re- 

 covered from their first feelings of fear. In this case the nesting 



