234 LIFE-HISTORIES OF BIRDS 



insects, small birds, and quadrupeds which they 

 overpower; their most remarkable habit is the 

 impaling of their prey upon sharp twigs, and 

 leaving them there. Various attempts have been 

 made to account for this curious habit, but the 

 most of them are very unsatisfactory. These 

 birds cannot be considered as strictly migratory. 

 The sexes are nearly alike. There are two well- 

 determined American species, the habits of one of 

 which we shall now proceed to portray. 



Collurio borealis, Baird. 



The Butcher Bird as we know this species of 

 shrike, is but a temporary resident in Eastern 

 Pennsylvania. It arrives in Philadelphia during 

 the latter part of October, and remains with us 

 until the last of March or the beginning of April, 

 when it retires to more northern habitats for 

 breeding purposes. The length of its sojourn 

 depends very materially upon climatic conditions. 

 It is never a very abundant species, and prefers to 

 lead during its stay a solitary life. Early in 

 Autumn it seeks the retirement of woods andlow 

 valleys which are places of resort for our smaller 

 winter denizens upon which it mainly subsists. 



When the ground is covered with snow, and the 

 smaller birds ard driven by necessity to seek their 

 own fare in the fields and yards of man, this 

 Shrike becomes less shy and ventures boldly into 

 such places. When not foraging it remains 

 perched upon a dead twig for half an hour at a 



