462 "U. S. NATIONAL MUSEUM BULLETIN 211 



advance over the previous day when it measured only 78 mm. The eyes opened 

 on the fifth day and the sheaths of the rectrices began to push through the skin 

 while those of the remiges began to open. The sixth and seventh days saw little 

 change except growth and unfurling of the feathers from their sheaths. 



The young Red-eye seems to get along with the rightful young in the nest better 

 than do the young of M. bonariensis or M. ater and it sometimes happens that 

 some of the rightful young survive with the parasite although in most cases the 

 legitimate young last but a few days in face of the competition of the Red-eye. 

 However, they do seem to survive longer with the young Red-eye than do young 

 Sparrows or Warblers with the young of M. ater. 



This may be partly due to the fact that the victims of the Red-eye are more 

 nearly its own size than are those of the other Cowbirds. * * * 



When about eleven days old the young Red-eyed Cowbird usually leaves the 

 nest and as a rule stays nearby for several days. For about two weeks and possi- 

 bly more it is cared for by its foster-parents and then shifts for itself. Usually 

 by the time this happens the season is well advanced as the Red-eye is a fairly 

 late breeder, and the young repair to the fields and marshes for the post-juvenal 

 molt. In these places all the young congregate from all the surrounding country- 

 side and when the molt is finished the birds come out in flocks. 



Alexander F. Skutch has sent me these notes on the young of this 

 species: "A nest of the green jay (Xanthoura luxuosa) found near 

 Matias Romero on the Isthmus of Tehuantepec, on July 8, 1934, 

 contained a single red-eyed cowbird [probably T.aeneus assimilis], well 

 feathered and almost ready to fly, sitting awake and alert between two 

 young jays, larger than itself but naked and slumbering. A nest of 

 the yellow-green vireo (Vireo jlavoviridis) , found near Colomba, 

 Guatemala, on July 26, 1935, contained one cowbird nestling in addi- 

 tion to three young vireos. * * * In the dry country about Zacapa, 

 Guatemala, on August 15, 1935, I saw a young cowbird being fed by 

 a female oriole — apparently either Icterus gularis or /. pectoralis, both 

 of which were numerous in the neighborhood, and difficult to distin- 

 guish unless they are adult males. On June 14, 1933, I saw, on the 

 edge of a maize field in the Guatemalan highlands at an elevation of 

 8,500 feet, a fledgling red-eyed cowbird attended by a pair of Guate- 

 malan spotted towhees (Pipilo maculatus repetens). While the 

 youngster clamored loudly for food, an adult cowbird alighted beside 

 it, and after an interval touched its open mouth with her (?) bill, but 

 I was too far away to see if any food was given. The adult cowbird 

 then flew off, and the towhee came and fed the dusky fledgling." 

 This observation does not prove that the cowbird was feeding its own 

 young, but is significant in connection with similar observations on 

 the eastern cowbird by Fletcher (1925). 



Plumages. — The plumages and molts of the red-eyed cowbird 

 differ from those of the eastern cowbird in that the young male does 

 not acquire the adult plumage until after the first postnuptial molt, 

 the second instead of the first fall; also, he has a partial spring molt. 



Friedmann's (1929) descriptions of the plumages and molts of the 



