SYLVIID.E — THE SYLVIAS. 79 



March, but are not known to winter in that latitude. All the specimens 

 in the Smithsonian collection were obtained between April and October, 

 except one from Southern California, which was taken in December. 



Near Washington, Dr. Coues states the Blue-gray Gnatcatcher to be a 

 summer resident, arriving during the first week of April, and remaining 

 until the latter part of September, during which 

 time they are very abundant. They are said 

 to breed in high open woods, and, on their first 

 arrival, to frequent tall trees on the sides of 

 streams and in orchards. 



In California and Arizona this species occiu^s, 

 but is, to some extent, replaced by a smaller 

 species, peculiarly western, P. mclanura. There 

 they seem to keep more about low bushes, hunt- 

 ing minute insects in small companies or in 



pairs, and their habits are hardly distinguish- Pohopnia rrpnUea 



able from those of Warblers in most respects. 



The food of this species is chiefly small winged insects and their larvae. 

 It is an expert insect-catcher, taking its prey on the wing with great 

 celerity. All its movements are very rapid, the bird seeming to be con- 

 stantly in motion as if ever in quest of insects, moving from one part of 

 the tree to the other, but generally preferring the upper branches. 



Nuttall and Audubon, copying Wilson, speak of the nest of this Gnat- 

 catcher as a very frail receptacle for its eggs, and as hardly strong enough to 

 bear the weight of the parent bird. This, however, all my observations 

 attest to be not the fact. The nest is, on the contrary, very elaborately and 

 carefully constructed ; large for the size of the bird, remarkably deep, and 

 with thick, warm walls composed of soft and downy materials, but abun- 

 dantly strong for its builder, who is one of our smallest birds both in size 

 and in weight. Like the nests of the Wood Pewee and the Humming-Bird, 

 they are models of architectural beauty and ingenious design. With walls 

 made of a soft felted material, they are deep and purse-like. They are not 

 pensile, but are woven to small upright twigs, usually near the tree-top, and 

 sway with each breeze, but the depth of the cavity and its small diameter 

 prevent the eggs from rolling out. Externally the nest is covered with a 

 beautifid periphery of gray lichens, assimilating it to the bark of the decidu- 

 ous trees in which it is constructed. 



Occasionally these nests have been found at tlie height of ten feet from 

 the ground, but they are more frequently built at a much greater eleva- 

 tion, even to the height of fifty i'eet or more. Tliey are made in the shape 

 of a truncated cone, three inches in diameter at the liase and but two at the 

 top, and three and a half inches in height. The diameter of the opening 

 is an inch and a half. In Northern Georgia they nest about the middle 

 of May, and are so abundant that the late Dr. Gerhardt would often find 



