1S8 



spiders, and other insect forms are also taken. The food of the species 

 throughout the year is regarded by the United States Biological Survey 

 as being beneficial in the ratio of 4 to 1. 



FAMILY VIREONID^E. VIREOS OR GREENLETS. L, 4-75-6-23. 



General Description. Small, warbler-like birds generally coloured in greens and white 

 with more or less yellow in softly suffused masses and without much definite marking. 

 The bill is perceptibly notched and hooked at the tip much like that of the Shrike (Figure 

 56, page 56), but is on a much smaller and much lighter scale. 



Distinctions. The Vireos are most apt to be mistaken for warblers which in habit, 

 size, and general coloration they resemble. The bills, however, are stouter, more strongly 

 arched on the culmen, higher for the width, and more evidently hooked and notched 

 at the tip. The Yellow-breasted Chat has a bill that might answer this description 

 in outline, but it is not hooked nor has it any indication of notch at tip. 



Field Marks. In addition to specific markings, which form the best guide to 

 species, the Vireos can be recognized by their warbler-like habits but slower and more 

 sluggish movements, peering under leaves and gleaning from the branches and twigs with 

 less activity. 



The Vireos constitute a small family peculiar to America. Three 

 genera occur in Canada, represented by six species. 



Economic Status. Economically the Vireos can be treated together 

 as they are similar in their food habits. Their food consists of 91 per cent 

 of insects and the remainder of fruits. The latter are almost without 

 exception wild varieties. The insects taken are among the most harmful, 

 including scales and other close lying species that no birds but the careful, 

 close-peering Vireos ordinarily seek. They are among our more useful 

 birds. 



624. Red-eyed Vireo. PREACHER-BIRD. TEACHER. FR. LE VIREO ATJX YEUX 

 ROUGES. Vireosylva olivacea. L, 6-23. Plate XXXVIII B. 



Distinctions. The Red-eyed can be distinguished from other Vireos by its superior 

 size, the lack of yellow, the grey confined to the crown, and the white eyebrow line bordered 

 with dark both above and below. The iris is red, but this can only be seen on very close 

 examination. 



Field Marks. The markings of the face of the Red-eyed makes the best field mark. 

 The white eyebrow bordered with darker colour and the lower line through the eye can 

 usually be seen as the bird peers through the leaves at the intruder. 



Nesting. Suspended from between the forks of a small branch 5 to 15 feet above the 

 ground in pensile nest or hanging-cup, woven of strips of bark, dead wood fibres, paper, 

 plant down, or birch bark lined with fine materials. 



Distribution. North America to near the limit of trees. 



The Red-eyed Vireo is one of the commonest frequenters of our 

 groves and woods. Its song, a leisurely repetition of slight variants of the 

 same phrase with pauses between, and continued ad libitum, can be heard 

 in the tree tops almost anywhere in Canada and has given the species the 

 name of Preacher-bird. 



626. Philadelphia Vireo. PR. LE VIREO DE PHILADELPHIE. Vireosylva phil- 

 adelphica. L, 4-75. Almost exactly similar in coloration to the Warbling Vireo (Plate 

 XXXIX A) but more generally suffused with yellow on breast, flanks, and below. 



Distinctions. The Philadelphia can always be separated from the Warbling Vireo by 

 the length of the first primary feather. In this species it is nearly as long as the second, 

 whereas in the Warbling it is reduced to a rudimentary condition and is barely three- 

 quarters of an inch in length. 



Field Marks. In life it looks like a Warbling Vireo with unusually yellow breast and 

 underparts. 



