﻿FOOD HABITS OF THE VIEEOS 23 



they make up 13.25 per cent and in February 11.88 per cent of the 

 food. In March the percentage drops to 4.79, in April to 0.52, and 

 in May and June none are eaten. A few are taken in July and 

 August, and by October as much as 20 per cent of the food may be 

 from this source. 



Other insects. — Miscellaneous insects other than grasshoppers make 

 up 3.74 per cent of the diet. The quantities eaten from month to 

 month show no coordination, and the item appears to be greatly 

 affected by chance. For instance, in January 5.68 per cent is to be 

 referred here, in February none, in March 8.68 per cent. 



Other animal food. — Spiders are at no time very abundant in the 

 food, although in August they form as much as 7.76 per cent of it. 

 The yearly average is 3.59 per cent. Other animal food is composed 

 mainly of snails, and in one stomach were bones of a small chameleon, 

 the two together making up only 0.37 per cent of the whole food. • 



VEGETABLE MATTER 



In the spring and f aU months foraging for suitable food compels 

 the birds to turn to the berries and small fruits, which are usually 

 to be had in ahnost any locaHty. In January 22.93 per cent of the 

 entire food is vegetable, in February only 5.62, still less from March 

 to July, in August 16.2, and in the next two months the percentage 

 rises to 32.37. The vegetable food is composed of such berries as 

 those of sumac, dogwood, wild grape, and wax myrtle, and has no 

 economic importance. 



SUMMARY 



There is remarkably little in the food habits of the white-eyed 

 vireos to condemn. The record of this species for the destruction of 

 ladybird beetles is not bad and is more than offset by the destruction 

 of many caterpillars, moths, plant bugs, and grasshoppers. These 

 birds take very few beneficial hymenopterans and no valuable fruit. 



THE BUTTON VIREOS 



Vireo huttoni, subspp. 



The Hutton vireos, in their subspecies, range over the greater 

 part of the Pacific coast and eastward into southern Arizona and 

 western Texas. Throughout their range birds of this species are 

 locally somewhat common in thickets along streams. There are in 

 the collection of the Biological Survey 77 stomachs available for 

 study, 70 of which contained sufficient food for use in the tabulations. 

 Unfortunately, these stomachs were not collected in consecutive 

 months, none in March, April, May, or November, and only a few 

 in each of the other months. The data available show a preponder- 

 ance of animal food (98.23 per cent), with but 1.77 per cent of vege- 

 table origin. It is probable that an investigation of more stomachs 

 will materially alter the conclusions reached at this time. (See 

 fig. 8.) 



ANIMAL FOOD 



The animal food is jnade up of insects and a few spiders, no trace 

 of the few moilusks usual with other vireos being found. Caterpillars 

 and other iepidoptcrous forms are not the dominating element of 



