328 BULLETIN 197, UNITED STATES NATIONAL MUSEUM 



nest beside the Eio San Antonio I had watched during the period of 

 incubation on May 12. The record I made on the spot tells the story 

 quite succinctly : 



May 17, 1940, 7: 25 a. m. I arrive at the vireos' nest and find the female 

 sitting. 

 7:32 She leaves the nest, carrying off the cap of a shell from which 



the nestling has emerged. (Whether the first, second, or thii'd, 



I cannot tell in this inaccessible nest.) 

 7 : 49 The male goes to look into the nest. 

 7 : 55 The female sits a fevs^ seconds, then leaves. Soon returns to 



brood. 

 8 : 07 She leaves as the male comes with food. 

 8: 10 She feeds a nestling. The male comes with food which he gives 



to her as she stands above the nest. She passes this on to a 



nestling, then flies off with the large half of a shell. 

 8 : 15 She returns, feeds a nestling, broods. 

 8 : 24 The male brings an insect to his mate. She rises up to feed a 



nestling, then continues to brood. 

 8 : 28 She leaves as the male comes with food. 

 8 : 29 He brings food again. 

 8 : 31 Tlie female delivers food, then departs. 

 8 : 34 The male comes singing with food in his bill. 

 8:36 The female brings food, then broods. 

 8 : 39 The male brings food to the female on the nest. 



It was easy to distinguish the male by his tireless singing. The 

 female uttered only the sharp rattle already described. The visits 

 the male had been in the habit of making to the nest during the course 

 of incubation kept him well informed of conditions there and ensured 

 his prompt attendance upon the nestlings when they hatched. In the 

 same sotacaballo tree where the vireos nested hung a black, retort- 

 shaped nest of a gray-headed flycatcher {Rhynchocydus cinereiceps). 

 The male apparently never went to look into it while it contained 

 eggs; and as a result of this negligence the nestlings were several 

 days old before he discovered their presence and began to bring food 

 to them. 



The nestling vireos are nourished with both animal and vegetable 

 food. Among the former is a variety of winged insects, including 

 big, green tree crickets — which are delivered to the youngsters wings 

 and all — and smooth caterpillars of various kinds. The vegetable 

 food consists of various kinds of berries, and the bright red, arillate 

 seeds of Clusia, a genus of thick-leafed epiphytic shrubs and trees 

 with fragrant white or pink blossoms. These red seeds are also an 

 important element in the diet of nestling blue honeycreepers {Cyan- 

 erpes cya/nea). During their first days, the mother vireo keeps the 

 naked nestlings covered most of the time. 



Though as a rule the male vireo helps feed his offspring, at the 

 nest where he was so inattentive during the course of incubation (on 



