326 BULLETIN 19 7, UNITED STATES NATIONAL MUSEUM 



minutes. Sometimes while sitting she uttered a sharp, rattling call ; 

 and each time she winged away at the end of a session she delivered 

 the same rattle. More rarely she voiced this call as she returned to 

 resume incubation. 



Her mate was most attentive. Wliile the female sat, he sang his 

 simple notes incessantly among the surrounding branches. From time 

 to time he went to look into the nest. As his mate returned from a 

 recess to resume incubation, he would hurry up to the nest and stand 

 beside it for a moment. This action, repeated three times in as many 

 hours, seemed an act of courtesy or formality, comparable to the cus- 

 tom of certain male flycatchers and tanagers of accompanying their 

 mates to the doorways of their closed nests as they return to their 

 eggs. Once the male vireo went to the nest while his mate was nearby 

 but not ready to resume sitting. She hurried up to stand beside the 

 nest, too, for a moment ; then both flew off again. These visits of the 

 male to the nest kept him informed as to the state of affairs there. 

 As we shall see, he was not tardy in bringing food after the eggs 

 hatched. 



The other nest was placed 11 feet above ground in a small Nectandra 

 tree in a weedy pasture beside the Buena Vista River. From conceal- 

 ment I made notes on it continuously from dawn to nearly midday 

 (5 : 15 to 11 : 33) on the drizzly morning of June 1, 1936. This female 

 vireo was neglected by her mate, who did not once come near the nest 

 during the entire morning. Her sessions on the eggs were of irregular 

 length, and varied from 15 to 61 minutes in no orderly fashion. Her 

 recesses were generally brief and ranged from 6 to 18 minutes; but 

 only twice were they in excess of 9 minutes. She spent a total of 256 

 minutes on the nest and only 85 away from it. On returning to the 

 nest, she never flew directly to it but always alighted on the other 

 side of the small tree and made her way to it from branch to branch. 

 As she neared her nest she almost invariably announced her coming 

 by the utterance of a rather sharp, nasal chaa. Usually she sat in 

 silence ; but once, when a male (her mate ? ) began to sing in a neighbor- 

 ing tree, she answered with a sharp, churred call. Upon leaving the 

 nest she flew directly from its rim, almost always uttering this pe- 

 culiar churred note early in her flight. Usually she flew to the 

 sotacaballo trees along the bank of the river a hundred feet away; 

 but when the male sang in the trees on the opposite side of the nest, 

 she went there to join him. 



During her recesses the female vireo ate many berries, principally 

 of some parasitic loranthaceous bush; and the indigestible seeds of 

 these she regurgitated at frequent intervals while sitting upon the 

 nest. These came up surrounded by a colorless, extremely viscous 

 substance, Avhich caused them to adhere to her bill so that she could 



