It is before the fierce heat of summer has begun to abate in the prairies of the west, that this little bird seeks its winter quarters. On the 18th of August I first met with it, on which day I shot two in different localities. One was hopping hurriedly about low bushes, and herbaceous weeds, not a foot from the ground, examining every stalk and twig, as it proceeded regularly but rapidly along the road-side, for insects. The other was differently engaged. It flew from a bush by the way-side as far as the middle of the road, when hovering in the air a few feet from the ground, it fluttered and turned hither and thither, and then flew back to nearly the same spot as that whence it had started. In a second or two it performed exactly the same manœuvres again; and then a third time, preventing, by the irregularity of its contortions, my taking aim at it, for some time. I have no doubt it was capturing some of the minute dipterous flies which were floating in the declining sun, in numerous swarms; but in a manner not usual with the Warblers. The stomach, in each specimen, was full of small fragments of insects. From that period to April, on the 11th of which month I last saw it, it was a very common resident in the bushes and low woods. Wilson describes the markings of the female as less vivid than those of the male; but two of that sex, which I shot in January, were in no respect inferior to the brightest males. Some have the red spots of the back almost, or even quite, obliterated; but this is not a sexual distinction. BLACK-THROATED BLUE WARBLER.[41] _Sylvicola Canadensis._ _Motacilla Canadensis_, +Linn.+ _Sylvia Canadensis_, +Lath.+—Aud. pl. 155. _Sylvia sphagnosa_ (_young_), +Bonap.+ [41] Length 5¹⁄₂ inches, expanse 8, flexure 2⁶⁄₁₀, tail 2¹⁄₈, rictus ¹¹⁄₂₀, tarsus ⁸⁄₁₀, middle toe ⁶⁄₁₀.