ARIZONA PYRRHULOXIA 31 



nest was generally smaller and more compactly built than that of the Cardinal, 

 but the difference was not as great as would be expected from the size difference 

 between the two species. 



Gould (1961) found the period of incubation to be 14 days from 

 the laying of the last egg. 



Incubation is probably performed entu-ely by the female. I have 

 never found the male on the eggs. As we watched a nest one morning 

 in May, the male arrived. The female uttered a few squick sounds, 

 not quite sharp enough to suggest alarm. Then the male flew to the 

 edge of the nest, slowly reached forward and gave the female a small 

 black insect which he carried in his bill. It was a thrilling and 

 altogether pretty sight — like two painted figures in red and gray on 

 a background of green. 



Both sexes assist in feeding their nestlings. When the fledglings 

 are sure of their wings, they follow their parents farther afield. Some- 

 times they traveled 300 to 400 yards from an abandoned nest in 

 the riverbank thicket to our back yard. They probably returned 

 to the safety of the mesquites each evening. The latest nesting I 

 have noted (Anderson and Anderson, 1946) was when "On Septem- 

 ber 9, 1945, a female appeared with a partly grown young bird that 

 followed her about, begging vociferously until it was fed. This beg- 

 ging note, a tseep or see'p sound, was heard frquently around our 

 house during the following days and, usually when we looked outside, 

 we found the female feeding the young bird. This dependence con- 

 tinued into the period of molt of the female. She appeared ragged on 

 October 1. On October 12 she was last seen feeding her offspring 

 which, at that time, was acquiring the male plumage. If we assume 

 that the incubation period is approximately two weeks, and that the 

 nestlings remain in the nest about ten days, then the eggs were 

 probably laid about the middle of August." 



Most of the adult birds seen in the latter part of October have 

 completed their fall molt. 



Eggs. — Gould (1961) reported that "The eggs of the two species 

 are very similar and cannot always be told apart. In the Tucson 

 area Cardinal eggs are somewhat larger and have a more bluish back- 

 ground color than those of the Pyrrhuloxia. The pattern of speckling 

 is identical." 



The measurements of 50 eggs average 23.9 by 17.7 millimeters; 

 the eggs showing the four extremes measure 26.2 by 17.2, 24.9 by 

 19.1, 22.2 by 17.5, and 23.0 by 16.0 milluneters. 



Plumages. — Mr. Bent says the young pyrrhuloxia in juvenal plum- 

 age is much like the adult female, but the plumage is softer, more 

 woolly, and the underparts are lighter in color, dull light grayish 

 buff, nearly white on the abdomen; the middle and greater wing 



