212 THE INVITATION. 



The rarest of the species are Swainson's warbler, 

 said to be disappearing ; the cerulean warbler, said 

 to be abundant about Niagara j and the mourning- 

 ground warbler, which I have found breeding about 

 the head-waters of the Delaware, in New York. 



The vireos, or greenlets, are a sort of connecting 

 link between the warblers and the true fly-catchers, 

 and partake of the characteristics of both. 



The red-eyed vireo, whose sweet soliloquy is one of 

 the most constant and cheerful sounds in our woods 

 and groves, is, perhaps, the most noticeable and abun- 

 dant species. The vireos are a little larger than the 

 warblers, and are far less brilliant and variegated in 

 color. 



There are four species found in most of our woods, 

 namely, the red-eyed vireo, the white-eyed vireo, the 

 warbling-vireo, and the solitary-vireo, — the red-eyed 

 and warbling being most abundant, and the white-eyed 

 being the most lively and animated songster. I meet 

 the latter bird only in the thick, bushy growths of low, 

 swampy localities, where, eluding the observer, it 

 pours forth its song with a sharpness and a rapidity 

 of articulation that are truly astonishing. This strain 

 is very marked, and, though inlaid with the notes of 

 several other birds, is entirely unique. The iris of 

 this bird is white, as that of the red-eyed is red, 

 though in neither case can this mark be distinguished 

 at more than two or three yards. In most cases, the 

 iris of birds is a dark hazel, which passes for black. 



