NESTING HABITS OF OROPENDOLA CHAPMAN 367 



February 10. No. 1 still strangling with her ontraucc. No. 2 has completed 

 hers and can now ^et insidf the be^inniuK of a ba^. 



February 14. No. 1 has brought the loose ends of her doorway together and 

 Is almost concealed when at work. 



In view of these facts it is obvious that the time re<iuiietl to buiUl 

 a nest depends, at least in a measure, on the skill, energy, and 

 persistence of the builder. This statement would call for no qualifi- 

 cation if all nests were uiade to the sauie moilel. They vary, how- 

 ever, in leii«j:th and in amount of liiiin<^. It is not impo.ssible that 

 when an undue amount of time has been spent on the earlier stages 

 of a nest it may be brought hastily to completion because of tlie 

 approaching needs of the female for a receptacle for the eggs. 

 When this need does not force a completion of the task, and conse- 

 quent closing of the nest bottom, the bag may be continued to the 

 maximiun length. 



In the absence of examination it is impossible to say exactly how 

 many days are reijuired to finish a nest. One may note the time 

 when the weaving of the bag is finished and its lining begun, but it 

 is not improbable that while the female is laying, or even after she 

 has begun to incubate, she may add to the nest lining. 



I have, therefore, accepted as evidence indicating the completion of 

 the nest its occupation at night. This is a definite, observable act and 

 obviously marks an important change in the attitude of the female 

 toward her home. Doubtless at or near this time the eggs are laid. 



Throughout the period of building, the females, as before stated, at 

 the end of a day's work accompany the males to the forest. They 

 usually go in a body, the males leading. But there comes a day when 

 the growing attachment of the female for her nest is stronger than 

 the impulse that induces her to follow the male to the roosting place. 

 The conquest of the old habit by the new one is recorded in my entry 

 for February 13, 1927 : 



To-night for the first tin>e this year the females were seen to enter the nests 

 for the nijiht. There was an unusual nunib<'r of birds in the colony at 6.10. 

 At about 6.15 they all flew off but returned at 6.18. Again they took flight 

 leaving, however, three females who, after preening, entiTed ue.sts Nos. 1, 2, 

 and 8 of group 1, respectively. 



After this event is inaugurated the gathering in the nest tree of the 

 members of the colony becomes a nightly habit. Even the birds 

 whose nests are not ready for occupation stay in the tree until those 

 whose homes are apparently completed enter them. All sit about 

 industriously preening their plumage in preparation for the night. 

 At about G.15 the first female enters her nest. She is soon followed 

 by otlicrs and by G.30 all who are to stay have gone to bed and the 

 remainder of the group fly to the forest. 



In 1926 this habit was first observed on February 7; in 1927, on 

 February 13. The 1928 colony was too much disturbed to develop it 



