294 LIFE HISTORIES OF NORTH AMERICAN BIRDS. 



Mr Charles E. Aiken states: "I have found several settled in the angle 

 formed by the trunk of the tree and a horizontal branch, and in one instance, 

 where a large limb had been torn from the tree by the wind, a nest was placed 

 flatly upon a broad, board-like splinter." 1 



Mr. L. Belding, in his Birds- of the Pacific District, 1890 (p. 99), makes 

 the following statement: "It almost always places its nest on a dead horizontal 

 limb, at least this is according to my observations, and I have seen many 

 nests which were saddled on limbs. In. a. solitary instance, however, the nest 

 was in or on horizontal diverging' twigs in a deciduous oak, where it was partly 

 hidden by foliage; again, one was nicely surrounded and to a grea,t extent con- 

 cealed by having been built-in a bunch of yellow lichen {Evernid)? 



Most of these birds nest in June; the earliest breeding record I have out 

 of thirty-nine is May 31, from Prescott, Arizona. I believe that but one brood 

 is raised in a season, although I have found nests with fresh eggs as late as July 

 15, probably second layings where the first had been taken or destroyed. The 

 Western Wood Pewee is very much attached to its nesting site when one has 

 been once chosen, and will frequently build a second nest in the same spot, or only 

 change the* location to some other limb of the same tree. It usually leaves its 

 breeding grounds for the south in September. 



The number of eggs to a set varies from two to four; sets of three are most 

 often found, while those of four are very rare. They can not be distinguished 

 from those of the preceding species, and the same description will answer for 

 both, but they are a trifle smaller. 



The average measurement of eighty-eight eggs in the United States National 

 Museum collection is 17.97 by 13.61 millimetres, or about 0.71 by 0.54 inch. 

 The largest egg of the series measures 19 05 by 15.24 millimetres, or 0.75 by 

 0.60 inch; the smallest, 16 by 12.95 millimetres, or 63 by 0.51 inch. 



The type specimens, Nos. 20536 and 20541 (PI. 2, Figs. 20 and 21), from 

 the Bendire collection, were taken by the writer at Fort Klamath, Oregon, on 

 Juy 7, 1882, and July 18, 1883, respectively, each set containing three eggs, 

 and these represent the heavier and lighter colored patterns of markings, while 

 No. 26063 (PI. 2, Fig. 22), from a set of two eggs, taken near Santa Ysabel, 

 California, by Mr. H. W. Henshaw, on June 9, 1893, represents an intermediate 

 type of coloration. 



1 Surveys West of the lOOta Meridian, Vol. V, 1875, pp. 354-355. 



