142 



BIRDS OF PENNSYLVANIA. 



SUBORDER CYPSELI. SWIFTS. 



FAMILY MICROPODID-ffi. SWIFTS. 

 SUBFAMILY CILS TURING. SPINE-TAILED SWIFTS. 



GENUS CHJETURA. STEPHENS. 

 423. Chsetura pelagica (LINN.). 



Chimney Swift. 



DESCRIPTION. 



Tail slightly rounded and spiny ; of a sooty brown all over, except on the throat, 

 which becomes considerably lighter from the breast to the bill ; above with a green- 

 ish tinge ; the rump a little paler. Length, 5.25 inches ; wing, 5.10; tail, 2.15. 



Hab. Eastern North America, north to Labrador and the fur countries, west to 

 the plains, and passing south of the United States in winter. 



The Chimney-bird, unless resting on its nest or clinging to the sooty 

 chimney sides, is always seen flying In Pennsylvania these birds are 

 generally first observed about the last week in April. In the early 

 autumn they collect in large flocks before retiring to their winter re- 

 sorts. I have observed birds of this species in Chester county (Pa.) 

 as late as the 20th of October. In this locality the nest of the Chim- 

 ney-Swift, or Swallow, as it is mostly called, is composed of small 

 twigs, which are glued together and to the sooty walls of unused 

 chimneys, with the birds' saliva.* The twigs used in constructing nests 

 are broken off of trees by these birds when on the wing. The eggs, 

 four to six in number, are white and unspotted. They measure about 

 three-fourths of an inch in length and about half an inch in width, 



FOOD. 



These birds subsist entirely on various kinds of insects which they 

 collect during the night as well as in daylight. 



* A writer in a recent scientific journal, which I have mislaid, says : " In the case of our own 

 Chimney-Swifts it has lately been shown that the gelatinous matter with which the twigs are 

 fastened together is of a vegetable and not an animal character, and in a particular case re- 

 cently investigated by a scientist, the gum was found to have come from a cherry tree." 



