200 Sketches of Some Common Birds. 



home a dainty nest with a complement of eggs, as I 

 remember from my own experience. 



The nest is made of soft plant fibers, pliant bark, and 

 fine grasses, neatly woven and compacted into a snug cup, 

 and cozily lined with small soft feathers and vegetable 

 down. The eggs are greenish-gray, spotted with reddish- 

 brown, the spots sometimes congregating in a ring about 

 the larger end. Four or five eggs are found in a comple- 

 ment, and they average .68 by .48 of an inch. 



In its economical relations the yellow warbler is very 

 beneficial, since its food consists almost exclusively of 

 insects harmful to vegetation. In an orchard infested 

 with canker-worms, five specimens of this warbler were 

 secured by Prof. S. A. Forbes, who reported that two- 

 thirds of their food were canker-worms, and the remain- 

 ing portions were noxious insects and spiders. It is 

 undoubtedly the interest of the horticulturist to encour- 

 age the presence of the yellow warbler, and to protect it 

 from the molestations of the usurping English sparrow 

 by driving the latter from his trees and buildings. 



The yellow warbler is subject to regular impositions of 

 the cowbird, nests being rarely found that do not contain 

 one or more eggs of the parasite. The warbler does not 

 always incubate these eggs, however, for experience has 

 doubtless taught it the results of receiving the stranger 

 into its embryonic family. Frequently it builds a floor 

 over the egg of the intruder, though it may often inclose 

 eggs of its own by thus adding a new story to its dwell- 

 ing. If the cowbird succeeds in placing its egg in the 

 second story, the warbler will sometimes add a third room 

 upon the second, for authentic observers have reported 

 nests containing two and even three incomplete sets of 

 eggs below the set which the warbler was incubating. 

 However, instances of such building to cover the eggs of 

 the parasite are not the rule. 



