24* LIFlMIISTORiKS OF BIRDS 



Dr. Brewer, was built on a high tree, carefully screened in- 

 dense foliage. It consisted of a simple platform of sticks 

 and grass, lined and matted with soft materials, such as 

 grasses and leaves. 



The parent-birds are said to manifest considerable con- 

 cern about their eggs and young, and to evince unmis- 

 takable evidences of anger and vexation when interfered 

 with. They are scarcely inferior in this respect to their 

 more courageous relatives. 



The young birds are said bv Audubon to be covered at 

 first with a yellowish down. 



The eggs varv from four to seven in number. They are 

 round-oval, or spherical in outline, and varv from creamv- 

 whiteto deep purplish-rufous in ground-color. A specimen 

 obtained from Great Salt Lake being, according to Mr. 

 Ridgway, completely and uniformly of the latter color; 

 while the lightest from Saskatchewan, is scattered with 

 faint and deep sepia-brown markings upon a creamy-white 

 background ; densely, upon the larger extremity, but sparsely 

 and finely, upon the smaller. Of twentv-one eggs whose 

 measurements were taken by the last-mentioned gentleman, 

 the largest from Yukon, measured 1.7^ by 1.28 inches; and 

 the smallest from Anderson river, 1.55 by 1.20 inches. 

 The eggs from Jamaica were round-oval or spherical in 

 contour, and were marked with confluent dashes and 

 blotches of sepia and amber upon an obscure clavish-white 

 ground-color, irregularly diffused, but principally about the 

 middle and the larger extremity. They measured 1.38 

 inches in length, and 1.13 in width. 



The variations in the shape and in the coloring of eggs can 

 be traced to their probable causes. According to Dr. Coues, 

 the former is chiefly produced by "difference in the length 

 of the major axis, the transverse diameter being approxi- 

 mately constant." The occurrence of additional variation 

 being probably due to a slight shifting of the maximum 

 width, towards the one or the other extremity. This theory 



