ORDER INSESSORES, OB. PERCHERS. 423 



of both hemispheres, moving towards the south at the approach 

 of winter, when specimens of it are sometimes found in Britain. 

 In fact, it is said to be a permanent resident in the Shetland 

 Isles. Another curious species is the Burrowing Owl, which is- 

 widely spread through the American continent, inhabiting the 

 burrows of the Marmot, Viscacha, and other small Rodentia ; and 

 when these do not present themselves, making -excavations for 

 itself. It is a small bird ; its length not exceeding ten inches. 

 The habit is not altogether peculiar to this species, for even the 

 Barn Owl occasionally takes up its abode in the burrows of 

 rabbits. 



ORDER II. INSESSORES. 



384. The group of Perching Birds, included in this order, 

 is the most numerous and the most varied in the whole class. 

 It comprehends all those tribes which live habitually among 

 trees, with the exception of the Rapacious Birds on the one 

 hand, and the Climbing Birds on the other. From the former 

 they are sufficiently distinguished, by the absence of those 

 characters which have been mentioned as peculiarly marking the 

 Birds of Prey ; and from the latter they are at once known by 

 the position of the toes. For in all the true Insessorial Birds, 

 the toes are three before and one behind (Fig. 205); whilst in 

 the Scansores, two of the toes are directed backwards (Fig. 187). 

 The adaptation of the foot of this order to grasping or perching, 

 is evident from the situation of the hinder toe ; which is in- 

 variably placed on the same level with those in front, and thus 

 distinguishes the Perchers from the Gallinaceous and Wading 

 Birds. These Birds pass the greater part of their time on the 

 wing, and only use their legs as an occasional support ; these 

 members are consequently short and wenk, in comparison with 

 those of most of the other orders. The toes are slender, flexible, 

 and of moderate length ; with long, slender, and slightly-curved 



