AlUZONA JAY 121 



should call it "Niagara green." The measurements of 136 eggs in the 

 United States National Museum average 30.28 by 22.26 millimeters ; the 

 eggs showing the four extremes measure 35.1 by 22.1, 28.7 by 24.6, 

 26.9 by 21.6, and 30.5 by 20.3 millimeters. 



Young. — Bendire (1895) says that "but one brood appears to be 

 raised in a season, and incubation lasts about sixteen days." Whether 

 both sexes assist in incubation and in the care of the young does not 

 seem to have been stated, but probably the care of the young, at least, 

 devolves on both. Swarth (1904) says that "soon after the first of 

 June young birds begin to appear, and by the middle of the month are 

 very much in evidence everywhere in the oak region ; first sitting in the 

 trees squalling to be fed, but very soon descending to the ground and 

 rustling for themselves." 



Dr. Walter P. Taylor tells me that he onc.e "saw an adult feed a 

 full-grown Juvenal by regurgitation." 



Plumages. — I have seen only small naked young, none with natal down. 

 The young bird in juvenal plumage is not strikingly different from the 

 adult in general appearance, though less blue above the browner below. 

 The top and sides of the head are dark gray, with hardly a trace of 

 blue; the rest of the upper parts are lighter and browner gray, includ- 

 ing the lesser wing coverts; the rest of the wings and tail are as in the 

 adult: the under parts are dull grayish brown; the base of the upper 

 mandible and most of the lower mandible are yellowish horn-color in 

 the dry skin, probably flesh-color in life. I have seen specimens in this 

 plumage from June 2 to August 2, when the postjuvenal molt begins; 

 this molt involves the contour feathers, but not the wings and tail ; it is 

 sometimes completed in August and sometimes not until October, but 

 I have seen young birds in fresh, first winter plumage in September. 

 The first winter plumage is worn until the first postnuptial molt the 

 following summer ; it can always be recognized by the yellowish base of 

 the lower mandible, which persists through the winter and spring; I 

 have seen it as late as May. Furthermore, young birds are always 

 duller colored than adults, less blue above and browner below, with 

 hardly a trace of blue on the breast; the wings and tails are also mucji 

 worn by spring. Young birds become fully adult, in plumage, at their 

 first postnuptial molt in August, but I think that some are able to breed 

 in their first winter plumage. 



Adults, with their bright blue plumage and wholly black bills, have 

 a complete postnuptial molt, between August and October. I have seen 

 them in worn plumage from June to August, and in wholly fresh plum- 

 age in September. 



