SPURRED TOWHEE 585 



him, both still singing from high up in the trees. Female squalling 

 from middle of orchard. Intruder male sings farther off to north 

 for quite a while. Original male returns and seen later scratching in 

 oak leaves around house. No more singing." 



Nesting. — In Utah nesting begins in April. The female builds her 

 nest in such great secrecy that we have never been able to witness 

 the entire process. We have seen females carrying nesting material, 

 and observed one just starting to build a nest under a small sagebrush 

 Apr. 21, 1938. AU the nests we have found were on the ground under 

 low bushes, usually sagebrush, and not in the dense, taller thickets 

 of scrub oak from which the males do most of their singing. The 

 nest is placed in a depression with the rim level with the ground 

 surface. It has an outer coarse shell of dried oak leaves and bark 

 and is lined with finer grasses. The cup ranges in diameter from 7 

 to 9 centimeters and in depth from 5 to 6 centimeters. 



A summary of nesting dates for the vicinity of Provo, Utah, is as 

 follows: May 5, nest and four fresh eggs found under a sagebrush; 

 May 6, nest and foiu' fresh eggs under a sagebrush; May 29, nest 

 with four eggs well advanced in incubation under a sagebrush, these 

 hatched June 2. For this same general area R. G. Bee and J. Hutch- 

 ings (1942) give nesting dates of May 20, May 25, June 1, June 10, 

 and June 26. 



Eggs usually number four, but we have seen as many as five and 

 as few as three apparently forming a fuU clutch. Their color, using 

 Ridgway's Color Standards, is near pale olive gray but lighter, and 

 finely speckled or spotted with army brown and sometimes blotched 

 with light mouse gray. Most of the eggs are heavily pigmented at 

 the large end. 



The measurements of 40 eggs average 23.6 by 17.8 millimeters; the 

 eggs showing the four extremes measure 25.9 by 18.6, 20.8 by 18.3, 

 and 23.9 by 16.8 millimeters. 



Incubation is apparently carried out entirely by the female. She 

 sits very closely during that period and may be approached within a 

 few feet or even a few inches before she will flush. She leaves the 

 nest by slinking rapidly over the ground to the nearest cover, and 

 her movements are so swift she may easily be mistaken for a small 

 mammal. She returns to the nest the same way, never by direct 

 flight to the site. Insofar as we have been able to observe, the male 

 does not approach the nest during the incubation period. We have 

 not been able to determine the length of the incubation periods in 

 P. e. montanus accurately, but our meagre information suggests that 

 it agrees with that of the eastern subspecies, P. e. erythrophthalmus, 

 recorded by F. L. Burns (1915) as 12 to 13 days. 



