THE VIREOS 



273 



birds to cease. They sing under the hottest noonday sun 

 when other birds are resting, and even on their way back 

 to their winter homes, they indulge in snatches of their 

 cheerful , measured music. Unlike the warblers , their songs 

 are uniformly loud and musical, and though sometimes 

 marred by a discordant chatter, they have a finesse 

 unusual in bird music. Their songs, however, are simple, 

 usually repeating the same phrase over and over with reg- 

 ular rests between each syllable. So measured is the time 

 that it is rather easy to distinguish the songs of the com- 

 mon species by the rate of deliverance. The red-eyed 

 vireo, for example, calls: "Look up" 1, 2, 3 "way up" 

 1, 2, 3 "tree top" 1, 2, 3, etc., while the yellow- 

 throated vireo, which has a somewhat harsher song, de- 

 livers it more slowly: "Cherries" 1, 2, 3, 4, 5 "sweet 

 cherries" 1, 2, 3, 4, 5, "have some," etc. 



This method of singing has given them the name of 

 "Preacher birds" and, as Wilson Flagg has well said of 



BUT THE COWBIRD WAS PERSISTENT 



The same nest containing two eggs of the vireo and twomoreof thecowbird. The 

 cowbird's eggs are larger and heavily specked. These eggs were removed, but later 

 another cowbird found the nest and the result is shown in the next photograph. 



the red-eyed vireo, "his style of preaching is not declama- 

 tion. Though constantly talking, he takes the part of a 

 deliberate orator, who explains his subject in a few words 

 and then makes a pause for his hearers to reflect upon it. " 

 The songs of the warbling and the white-eyed vireos are 

 exceptional, for the former indulges in a single, long, mus- 

 ical warble, similar to the song of the purple finch, except 

 that it has a rising inflection at the end, while the latter, 

 being an excellent mimic, often combines the songs of 

 other birds with his own, into an indescribable jumble of 

 musical cadences. 



The nests of vireos are basket-like structures hung in 

 the forks of the smaller branches. They are built of strips 

 of grape vine bark and fibers, such as the milkweed sup- 

 plies, skilfully fastened together and bound in place by 

 spider or tent caterpillar webs. One can be fairly certain 

 of the species of the nest by its position in the tree or shrub. 



The white-eyed vireo, for example, always builds its nest 

 in berry bushes or tangled thickets within a few feet 

 of the ground. The red-eyed vireos nest on the 

 lowest branches of trees or in young saplings from 

 five to ten feet from the ground. The warbling vireo 

 builds high in a full-grown tree toward the tip of the. 

 branches, while the yellow-throated builds near the trunk 

 or one of the main branches, hanging its nest in the fork 

 of a small shoot. The eggs of vireos are always white 

 with just a few specks of black about the larger end. 



AND THIS IS THE RESULT 



The young cowbird now ready to leave the nest of the blue-headed vireo from 

 which it has long since crowded the rightful young. 



The whole vireo family is very commonly parasitized 

 by the cowbird, a species of blackbird, which, like the 

 European cuckoo, builds no nest of its own but always 

 deposits its eggs in the nests of smaller birds. The cow- 

 bird's eggs are easily distinguished because they are larger 

 and heavily specked with brown, but, in spite of the great 

 dissimilarity, the vireo seems not to recognize the differ- 

 ence and never throws the egg from the nest. If, however, 

 the cowbird deposits an egg before any of the vireo eggs 

 have been laid, the vireo seems to realize the intrusion 

 and will often build a floor over the cowbird's egg and thus 

 prevent its hatching, or it may even desert its nest and 

 build another. Apparently the vireos cannot count higher 

 than one, and, while they recognize the difference between 

 an empty nest and one containing an egg, they do not 

 seem to differentiate between one egg and two, or between 

 two and three. 



If the cowbird's egg hatches it is seldom that even one 

 of the young vireos reaches maturity, for the young cow- 

 bird quickly outstrips them and gets all the food, so that 

 they are either starved to death or crowded from the nest. 

 The vireo, however, is no less faithful to this changeling 



