XXVI INTRODUCTION. 



penters, and without the aid of any other chisel than their 

 wedged bills. 



But the most consummate ingenuity of ornithal architecture 

 is displayed by the smaller and more social tribes of birds, who, 

 in proportion to their natural enemies, foreseen by Nature, are 

 provided with the means of instinctive defence. In this labor 

 both sexes generally unite, and are sometimes occupied a week 

 or more in completing this temporary habitation for their 

 young. We can only glance at a few examples, chiefly domes- 

 tic ; since to give anything like a general view of this subject 

 of the architecture employed by birds would far exceed the 

 narrow limits we prescribe. And here we may remark that, 

 after migration, there is no more certain display of the reveries 

 of instinct than what presides over this interesting and neces- 

 sary labor of the species. And yet so nice are the gradations 

 betwixt this innate propensity and the dawnings of reason that 

 it is not always easy to decide upon the characteristics of 

 one as distinct from the other. Pure and undeviating in- 

 stincts are perhaps wholly confined to the invertebral class of 

 animals. 



In respect to the habits of birds, we well know that, like 

 quadrupeds, they possess, though in a lower degree, the capa- 

 city for a certain measure of what may be termed education, 

 or the power of adding to their stock of invariable habits the 

 additional traits of an inferior degree of reason. Thus in those 

 birds who have discovered (like the faithful dog, that humble 

 companion of man) the advantages to be derived from asso- 

 ciating round his premises, the regularity of their instinctive 

 habits gives way, in a measure, to improvable conceptions. In 

 this manner our Golden Robin (^Icterus baltimore) , or Fiery 

 Hang Bird, originally only a native of the wilderness and the 

 forest, is now a constant summer resident in the vicinity of 

 villages and dwellings. From the depending boughs of our 

 towering elms, and other spreading trees, like the Oriole of 

 Europe, and the Cassican of tropical America, he weaves his 

 pendulous and purse-like nest of the most tenacious and dur- 

 able materials he can collect. These naturally consist of the 



