ZOOLOGY BIRDS. 39 



there has not seen one, though giving much of his attention .to the migratory habits of such 

 birds as pass through that section of country. I was therefore surprised on meeting this species 

 after sixty miles of travel through the Colorado desert in the vicinity of the Little Lagoon. 

 On nearing the Colorado river they increased greatly in numbers, twenty or thirty being often 

 seen on the wing at a time. In November, the period of their migration southward, they are 

 very abundant in this section of country. They usually perch on the mesquite trees, jerking 

 their tails almost incessantly, as do some species of fly-catchers, emitting, the while, a low 

 plaintive whistle, and dashing occasionally in irregular curves and angles high in the air in 

 pursuit of insects. 



POLIOPTILA CAERULEA, Gm el .Blue- gray Gnat-catcher. 



Culicivora caerulea, DEKAY, N. Hist. N. Y. Part I, p. 109, pi. 56, fig. 126. 



Muscicapa caerulea, AUD. Fol. pi. 84. WILS. Am. Orn. vol. II, p. 1C4, pi. 18, fig. 5. NUTT. Orn. vol. I, p. 297. 



Abundant. 



POLIOPTILA MELANURA, L a w r .Black-headed Gnat-catcher. 



Culicivora mezicana, (BONAP.) CASSIN S B. of Texas and California, p. 163, pi. 27. 

 Polioptila melanura, BAIRD, Gen. Eep. IX. 



I first came across this species near San Diego, in 1851, and found it abundant during the 

 recent survey in the vicinity of Fort Yuma, The last specimen I obtained was from a hedge 

 surrounding the cultivated fields of the Pimos Indians, whose villages are situated about two 

 hundred miles above the junction of the Gila and Colorado rivers. Its habits resemble those of 

 the preceding species, quick and restless in its movements, searching actively for its food, and 

 darting occasionally in the air in pursuit of small insects. Its note is of so feeble a tone as to 

 be heard only at the distance of a few yards. In searching its food it resorts, from preference, 

 to low trees and weeds, where it finds the most copious harvest. 



MYIODIOCTES PUSILLUS, Wilson .Green Black-capped Fly-catching Warbler. 



Muscicapa pusilla, WILS. Am. Orn. vol. Ill, p. 103, pi. 26, fig. 4. AUD. B of A. Fol. pi. 124. 

 Myiodioctes wilsonii, AUD. B. of A. Oct. vol. II, p. 21, pi. 75. 

 Myiodioctes pusillus, BAIRD, Gen. Rep IX, 293. 



During our expedition this species proved abundant, being found wherever the wood or 

 heavy brush and thickets afforded it a sufficient shelter. 



DENDROICA AUDUBONII, Towns . Audubon s Warbler. 



Sylvicola audubonii, TOWNS. Audubon, B. of A, Oct. vol. II, p. 26, pi. 77. 



Sylvia audubonii, TOWNS. Jour. Acad. N. Sci. Phil. vol. VII, p. 191. AUD. B. of A. Fol. pi. 395. 



Dendroica audubonii, BAIRD, Gen. Rep. IX, 273. 



Abundant, replacing in California the Sylvicola coronata of our eastern States. It assembles 

 in the fall and spring in small flocks, often associated during their migrations with the titmouse 

 (Parus) and ruby- crowned wren, (Regulus calendula,} skipping about in the tree tops, actively 

 searching for insects, oftentimes flying in the air in their pursuit. Some few of these birds 

 spend the whole winter in California, as I have seen them in Sacramento valley throughout all 

 the inclement season. 



