486 LIFE HISTOEIES OF NORTH AMERICAN BIRDS. 



about two weeks old, and may then be seen sitting on some of the branches 

 close by and clamoring for food. They are fed entirely on insects, etc., and are 

 faithfully cared for by the parents until able to provide for themselves. The 

 migration from the northern sections of their breeding range to their winter 

 homes in Central America begins usually in August, but occasionally some birds 

 linger until September. This species is rarely imposed on by the Cowbird. The 

 eggs of the Baltimore Oriole are usually elongate ovate in shape, more rarely 

 ovate. The shell is fine grained, moderately strong, and shows but little gloss. 



The ground color is ordinarily pale grayish white, one of those subtle tints 

 which is difficult to describe ; in a few cases it is pale bluish white, and less often 

 the ground color is clouded over in places with a faint, pale ferruginous suffusion. 

 The egg is streaked, blotched, and covered with irregularly shaped lines and 

 tracings, generally heaviest about the larger end of the egg, with different shades 

 of black and brown, and more sparingly with lighter tints of smoke, lavender, 

 and pearl gray. In a few instances the markings form an irregular wreath, and 

 occasionally a set is found entirely unmarked. 



The average measurement of fifty-six eggs in the United States National 

 Museum collection is 23.03 by 15.45 millimetres, or about 0.91 by 0.61 inch. 

 The largest egg of the series measures 25.91 by 16.76 millimetres, or 1.02 by 

 0.66 inches; the smallest, 20.83 by 14.99 millimetres, or 0.82 by 0.59 inch. 



Of the type specimens, No. 22644 (PL 7, Fig. 6), from a set of four, taken 

 by the late Capt. B. F. Goss, near Pewaukee, Wisconsin, on June 7, 1872, shows 

 a rather unusual type of markings; No. 25557 (PI. 7, Fig. 7), from a set of five, 

 Ralph collection, taken on Shelter Island, New York, June 10, 1882, represents 

 one of the finer and more profusely marked examples; No. 25558 (PI. 7, Fig. 8), 

 also from a set of five, taken by Dr. William L. Ralph, near Holland Patent, 

 New York, June 3, 1887, shows the coarser style of markings and a rather dark 

 ground color; and No. 25846 (PI. 7, Fig. 9), from a set of four, taken on June 

 7, 1887, by the same collector and at the same place as the last, shows a speci- 

 men in which the markings are mainly confined to the center of the egg. 



190. Icterus bullocki (Swainson). 



BULLOCK'S ORIOLE. 



Xanthornus bullocM Swainson, Philosophical Magazine, I, 1S27, 436. 

 Icterus bullocTci Bonaparte, Geographical and Comparative List, 1838, 29. 

 (B 41C, C 217, R 272, C 327, U 508.) 



Geographical range: Western North America; north to southern British Colum- 

 bia, southern Alberta, and Assiniboia, Dominion of Canada; east to western North and 

 South Dakota, western Nebraska, eastern Colorado, and western Texas; Lower California; 

 south in winter into the valley of Mexico and to Puebla. Accidental in Maine. 



Bullock's Oriole, a species as handsome and conspicuous as the preceding 

 one, replaces it in the western portions of the United States, and is likewise 

 widely distributed. Its breeding range within our borders corresponds to its dis- 



