274 ORNITHOLOGY AND OOLOGY. 



The Warbling Vireo seems to arrive here in pairs ; for they 

 seem to be mated when we first discover them. Whether 

 their attachment continues through several seasons, I am 

 ignorant. 



About the middle of May, the pair commence building. 

 The nest is pensile, and usually built in tall trees (usually 

 poplars), often fifty feet from the ground. It is constructed 

 of strips of grape-vine bark, grass, leaves, or bass-wood 

 bark ; and sometimes bunches of caterpillars' silk are left on 

 the outside, as if for ornament. The following very inter- 

 esting account of the breeding habits of this bird is given 

 by Audubon, who watched a pair building in a Lombardy 

 poplar : 



"One morning, I observed both of them at work: they had 

 already attached some slender blades of grass to the knots of the 

 branch and the bark of the trunk, and had given them a circular 

 disposition. They continued working downwards and outwards 

 until the structure exhibited the form of their delicate tenement. 

 Before the end of the second day, bits of hornets' nests and particles 

 of corn husks had been attached to it by pushing them between the 

 rows of grass, and fixing them with silky substances. On the third 

 day, the birds were absent, nor could I hear them anywhere in the 

 neighborhood ; and, thinking that a cat might have caught them from 

 the edge of the roof, I despaired of seeing them again. On the 

 fourth morning, however, their notes attracted my attention before 

 I arose ; and I had the pleasure of finding them at their labors. 

 The materials which they now used consisted chiefly of extremely 

 slender grasses, which the birds worked in a circular form within 

 the frame which they had previously made. The little creatures 

 were absent nearly an hour at a time, and returned together, bring- 

 ing the grass, which, I concluded, they found at a considerable 

 distance. Going into the street to see in what direction they went, 

 I watched them for some time, and followed them as they flew from 

 tree to tree towards the river. There they stopped, and looked as 

 if carefully watching me, when they resumed their journey, and 

 led me quite out of the village to a large meadow, where stood an 

 old hay-stack. They alighted on it, and, in a few minutes, each had 



