236 LIFE HISTOrJES OF NORTH AMERICAN BIRDS. 



About one-third of the eggs are unspotted. In shape they vary from an 

 elHptical oval to an oval. Now and then one occvirs that may be designated 

 as elliptical ovate. The shell is fairly smooth and close grained. 



The average measurement of fifteen eggs of this species in the U. S. 

 National Museum collection is 60 by 47.5 millimetres; the largest egg meas- 

 uring C5 by 50, the smallest 55 by 44 millimetres. 



The type specimen No. 22581, selected from a set of tlu'ee, taken March 8, 

 1882 (PI. 7, Fig. 8), is the heaviest marked egg of the series, but in another 

 egg of this set the spots, while fewer, are darker colored, and No. 22583, fi'om 

 a set of two, taken April 4, 1SS5 (PI. 7, Fig. 9), shows but a trace of a faint 

 spot here and there, and resembles an unspotted egg. Both these sets were 

 olitained in exchange from Capt. B. F. Goss, and were taken near Coqius 

 Christ!, Texas. 



8i. Buteo swainsoni Bonaparte. 



swainson's hawk. 



Buteo sivainsoni Bonaparte, Geogi-apliical and Comparative List, 1838, .3. 

 (B 18, 19, 21, 28, C ;35-4, R 412, C 523, U 342.) 



Geographical range: Western North America; uortli to Alaska aud western side 

 of Hudson Bay; east to Wisconsin, Illinois, and Arkansas (casually to Massachusetts); 

 and south through Central America and greater part of South America to the Argen- 

 tine Republic. 



Swainson's Hawk has a wide distribution during* the breeding season. 

 Commencing with the southern portion of its range east of the Rocky Moun- 

 tains — this includes portions of the less densely timbered and prairie regions 

 of Texas and Arkansas — thence northeastward in similar localities to Illinois 

 and Wisconsin; north and westward through the intervening States and Terri 

 tories into the Dominion of Canada from Manitoba, westward and north to 

 the Arctic regions in about latitude 65°. West of the Rocky Mountains it 

 is found in New Mexico and Arizona, aud over the entire Pacific coast region 

 north into British Columbia and Alaska. 



On the arid wastes and talkie lands of southern Arizona, as well as in the 

 sage and bunch grass districts of Nevada, Oregon, W^ashington, and Idaho, 

 Swainson's Hawk^ is especially abundant, outnumbering, perhaps, all the other 

 Raptores of these regions combined. It is eminently a prairie bird, shunning 

 the densely timbered mountain regions, and being more at home in the 

 sparingly wooded localities usually found along the water courses of the low- 

 lands. 



Compared with the majority of our Hawks it is gentle and imsuspicious in 

 disposition, living in perfect harmony with its smaller neighbors. It is no 

 unusual sight to find other birds, such as the Arkansas Kingbird, Tyrannies ver- 

 tical is, and Bullock's Oriole, Icterus huJJocln, nesting in the same tree; and the 

 first-mentioned species goes even further than this, sometimes constructing its 



