HUTTON'S VIEEO 245 



Plumages. — According to Kidgway (1904) young Hutton's vireos, 

 in Juvenal plumage, are "similar to adults, but much grayer olive 

 above, under jDarts much paler (chin, throat, and chest very pale olive- 

 grayish), and auricular and suborbital regions pale as throat, etc., 

 thus reducing contrast with pale orbital ring and supraloral line." 



Young birds apparently have a partial postjuvenal molt, mainly 

 in August, which involves the contour plumage and the wing coverts 

 but not the rest of the wings nor the tail. The first winter plumage 

 is practically indistinguishable from that of the adult, i^dults have 

 a complete postnuptial molt that sometimes begins at the end of July 

 and may continue through September. 



Food. — Dr. Edward A. Chapin's (1925) report on the food of the 

 Hutton vireos is based on the study of 77 stomachs, only 70 of which 

 contained enough food for use. Furthermore, none of these were 

 collected in March, April, INIay, or November, and so the results are 

 not as satisfactory as they might be. There was a preponderance of 

 animal food, 98.23 percent, made up of insects and a few spiders, but 

 none of the small mollusks usual with other vireos. Nearly 46 percent 

 of the food consisted of bugs (Hemiptera), nearly half of them stink 

 bugs. Caterpillars, moths, and butterflies made up nearly one-quarter 

 of the total food; beetles 13.25 percent, of which 8.12 percent were 

 the useful ladybird beetles and 2.75 percent weevils. Other insects 

 were eaten in small quantities, but spiders were found in all stomachs, 

 averaging 2.05 percent. These vireos seem to eat too many ladybird 

 beetles and not enough caterpillars, to compare favorably with other 

 vireos. 



Professor Beal (1907), in his earlier report, mentions among the 

 Hemiptera : "Assassin-bugs, leaf-bugs, stink-bugs, leaf-hoppers, jump- 

 ing plant-lice, and bark scales." In the somewhat less than 2 percent 

 of the vegetable food, he adds : "One stomach contained a few seeds 

 of elderberries, two contained those of poison oak, and these with a 

 few galls and some rubbish make up the whole of this part of the 

 food." 



Behavior. — Hutton's vireo is a quiet, modest, unobtrusive bird that 

 must be sought for to be seen in its shady retreats, where its olive- 

 green plumage blends so well with the foliage that it is far from con- 

 spicuous and it is not sufficiently active to attract attention. Mr. 

 Van Fleet (1919) describes its behavior very well as follows: 



The Hutton Vireo is not a bird likely to draw attention to himself. There is 

 no fluttering of wings or hasty glances here and there for food, such as dis- 

 tinguishes the Kinglet ; no hammering or pounding and gay chattering or scold- 

 ing, in the manner of the Plain Titmouse. His sober mantle of olive green is 

 not less subdued than his movement from branch to branch, and tree to tree, 

 his quiet peering under leaves and bark scales, where he takes toll of the teeming 

 insect life. Occasionally a large insect will fall his prey ; he will then stop and 

 diligently snip off the wings and legs before attempting to swallow it. Rarely, 



