OF EASTERN PENNSYLVANIA, 135 



which varies from a week to ten days, its food 

 consists principally of, insects. Within the stom- 

 achs of several individuals which we have ex- 

 amined, have been noticed the following: — For- 

 mica sanguinea, and F. subterranea, in great 

 abundance; Scarites subterraneus, Harpalus fensyl- 

 vanicus, H. compar, Casnonia pennsylvanica, larvSe 

 of Cratonychus cinereus, Platynus cupripenwts, 

 Chl(enius sericeus, Cratonychus pertinax, Musca 

 domestica, Tabanus lineola, Culex tcBniorhynchus, 

 and others, which we were unable to identify. 

 The berries of yuniperus Virginiana are dcca- 

 sionally eaten. With the above a few seeds 

 of graminaceous plants, fragments of leaves of 

 • grasses, and buds oi Acer rubrum were detected. 



We are inclined to believe that it does not stop 

 during its southern migration, since its non- 

 appearance in habitual habits, is a notable fact. 



Ordinarily, a rare visitor in our latitude, it is 

 very abundant at certain times, but is iaiways 

 observed as isolated individuals. A combina- 

 tion of circumstances apparently determines the 

 period of its maximum and minimum numbers. 

 During the breeding-season, and also during mi- 

 gration, birds are at times very differently circum- 

 stanced. Sometimes, surer success attend their 

 procreative "and parental endeavors, and larger 

 numbers of young are reared. Again, particular 

 species escape more successfully the assaults 6f 

 predatory birds, and the warfare of man, and are 

 thus enabled to bring greater numbers to accus^ 



