BLACK-CAPPED VIREO 225 



is similar to that of the adult, "but without black or clear gray on 

 head, which is replaced by grayish brown or brownish gray; olive- 

 green of back, etc., browner ; white of under parts and head markings 

 much less pure, strongly washed with pale buff or brownish buff, the 

 sides and flanks more brownish olive-green." 



The sexes are alike in the juvenal plumage, but quite different after 

 the post juvenal molt. For many years it was thought that the sexes 

 were alike in all plumages, as they are in most of the vireos, but 

 now it seems to be well-established that the black head markings of 

 the male are replaced by slate-gray in the female ; the wing bars and 

 light edgings of the tertials are yellow in the male and whitish in the 

 female ; the olive-green of the back is duller in the female and the white 

 of the underparts and head is less pure than in the male. The iris 

 in both sexes is said to be light brick red: Van Tyne and Sutton 

 (1937) call it "a striking shade of light, clear, reddish brown — this 

 shade in sharp contrast to the whiteness of the eye ring and blackness 

 of the cap." 



I have seen no molting birds. 



Food. — There seems to have been no comprehensive study made of 

 the food of the black-capped vireo. Mr. Simmons (1925) makes the 

 brief statement that it "feeds low among the dwarf shin oak and 

 scrub oak or dwarf plum thickets on ridges and dry hillsides, search- 

 ing for caterpillars, other insects, and their eggs." 



Behavior. — Mr. Simmons (1925) says that it is "observed singly or 

 in pairs. Very shy and quick, dodging in and out among thick foliage 

 of bushes, and from one dense clump to another; alert, active, and 

 energetic, hopping and flying briskly about, generally keeping close 

 to cover of bushes." 



Evidently the quiet demeanor and deliberate, leisurely movement, 

 so characteristic of most vireos, are quite lacking in the blackcap, 

 for all observers seem to agree on its restless activity. Some say that 

 it can be easily approached to within a reasonable distance and is 

 really not very shy, but that its constant hopping and flitting about in 

 the thick foliage m.ake it a difficult bird to collect. Several have men- 

 tioned being able to almost touch it on the nest when incubating. Van 

 Tyne and Sutton (1937) observed that "the birds were given to drop- 

 ping from one perch to a lower perch, letting their bodies swing 

 downward while still holding tightly with their feet, then suddenly 

 letting go." 



Voice. — The black-capped vireo must be a very striking and quite 

 versatile singer, but one easily recognized when t\\Q form of its song 

 is once learned. Mrs. Nice (1931) listened to one singing in Okla- 

 homa, of which she writes : 



He sang continuously, giving an extraordinary variety of phrases, all of them 

 harsh, vehement and unmusical. One phrase (tee tear ticit) reminded me of a 



