240 LIFE HISTORIES OF i^fOETH AMEEICAN BIRDS. 



any of our Hawks. 'Tame' is an appropriate epithet. A pair spent many 

 days in rebuilding an old nest of the common Crow 15 feet up in a small 

 tree, directly over a road in a wood and in plain sight, yet the birds evinced 

 no more concern about the passers-by than a Bantam hen would do. It is 

 popularly known as the Prairie Hawk here, and so it is, but it often nests 

 in the bordering groves." According to Mr. W. H. Cobb, in New Mexico 

 they occasionally nest in canons or the sides of cliffs under an overhanging 

 rock. Here they feed principally on hares and wood rats, and remains of 

 snakes have been found in one of their nests. 



A nest whose contents are now in the U. S. National Museum collec- 

 tion, taken at the forks of Milk River, Montana, on July 17, 1874, by 

 Dr. Elliott Coues, was placed against the face of a perpendictilar earth bank 

 100 feet high, on a slight projection of the ground about half way up. It 

 contained two eggs in which incubation was far advanced. Nests have also 

 been found in live oaks, sycamores, and aspens. 



Lieutenant Benson found Swainson's Hawk living in harmony with 

 other birds and writes me that after the Arkansas Kingbirds began to build 

 he invariably found one of their nests in each tree that contained one of the 

 former. In one case a pair of these flycatchers had placed their nest 

 directly under and but 8 or 9 inches from that of the Hawk. A pair of 

 White-rumped Shrikes nested also directly under one of these Hawk's nests. 

 On another occasion he found rather a strange occupant in a nest of this 

 species, and it is questionable if, in this instance at least, the usually good- 

 natured Swainson's Hawk would not have resented the intrusion. This 

 visitor was a good-sized rattlesnake which had managed to climb up the low 

 bushy tree and coiled itself comfortably in the nest. 



But one brood is raised in a season. If the first set is taken they will 

 frequently lay a second one consisting of one, seldom two eggs, and use 

 the same nest again as a rule. Incubation lasts about twenty-eight days, 

 both sexes assisting, and the eggs are deposited at intervals of about two 

 days. 



The number of eggs to a set varies from two to four. According to my 

 own experience, and that of Lieutenant Benson as well, the number most often 

 found is two. About one nest in four contains three eggs, and a set of four is 

 rarely met with. I found but one such in over thirty nests, and the only other 

 set in the collection was taken by Mr. Ernest E. Thompson, near Carberry, 

 Manitoba, June 8, 1883. My set of four was taken near Fort Lapwai, Idaho, 

 May 28, 1871. 



In shape these eggs vary from a short ovate to an oval, and their shells are 

 rather smooth and close grained. Their ground color when fresh is a very dis- 

 tinct greenish white which in course of time fades into a dull yellow white. 

 When not closely looked at many of the eggs of Swainson's Hawk appear to 

 be unspotted, but on careful examination there are in reality very few that are 

 immaculate. The majority are more or less distinctly spotted and blotched 



