212 LIFE HISTORIES OF NORTH AMERICAN BIRDS. 



and only occasionally is a heavily blotched set found. In shape, some are 

 nearly oval, one end however, is generally a trifle smaller. Many are ovate 

 or short ovate. 



The shell in most specimens is coarse and strongly granulated, but now and 

 then an egg is found that is much closer grained and feels rather smooth to the 

 touch. The average measurement of a series of eighty- three eggs is 60 by 

 47.5 millimetres. The largest egg in this series measures 65.5 by 50, the 

 smallest 55.5 by 45 millimetres. 



Inasmuch as there is no perceptible difference in the eggs of the Red-tailed 

 Hawk and its geographical subspecies, the type specimens have been selected 

 from the whole series to show as nearly as possible the variations in markings 

 irrespective of race. Those figured (of Buteo borealis proper) show the unmarked 

 type and a fairly well-spotted egg. 



Of these, No. 12740 (PI. 6, Fig. 5), a plain colored egg, was collected in 

 Richland County, Illinois, by Mr. Robert Ridgway, of the Smithsonian Insti- 

 tution, on March 6, 1887, and No. 23610 (PI. 6, Fig. 6), a distinctly and fairly 

 well-marked egg, was taken by Mr. J. W. Preston, near Baxter, Iowa, April 7, 

 1888. They are from sets of two eggs. 



72. Buteo borealis kriderii HOOPES. 



KRIDER'S HAWK. 



Buteo borealis var. kriderii HOOPES, Proceedings Academy Natural Sciences, Phila., 



1873, 238, PI. 5. 

 (B , C 351c, R 436a, C 519, U 337a.) 



GEOGRAPHICAL RANGE : Great Plains of the United States, from Minnesota to 

 Texas; east, irregularly or casually to Iowa and northern Illinois. 



Very little is yet known regarding the exact limits of the breeding range 

 of Krider's Hawk, a light-colored race of the Eastern Red-tail. It seems to be 

 restricted to the plains proper, and up to the present time has been found more 

 frequently in western Minnesota during the breeding season than anywhere 

 else, though nowhere abundant. Col. N. S. Goss states that it breeds occasion- 

 ally in western Kansas. Mr. George G. Cantwell gives it as a summer resident, 

 in his recently published list of the "Birds of Minnesota," and he writes me 

 that he found a nest of this Hawk on May 18, 1889, containing three eggs. It 

 was placed in an elm tree about 50 feet from the ground, situated in a grove 

 which fringed the Lac-qui-parle River, near Dawson, Minnesota. The structure 

 of the nest, as well as the eggs, he says, were similar to those of the common 

 Red-tail. 



Messrs. Thomas S. Roberts and Franklin Benner, in speaking of Krider's 

 Hawk, say: "On the 17th of June we took from one of the large cottonwood 

 trees on the border of the Minnesota River, in Brown's Valley, a young HaAvk, 

 not more than a week old, which we brought back to Minneapolis with us. 



