72 BULLETIN 17 9, UNITED STATES NATIONAL MUSEUM 



Colo., "in scrub-oak, cotton woods, quaking-asps, and gate frames, on 

 log fences, and on the top of a large farm gate. The birds are of a 

 sociable disposition, nests being rarely found any great distance 

 from human habitation." 



The bulky nests of the Cassin's kingbird are much like those of 

 the Arkansas kingbird, but will average somewhat larger and rather 

 more firmly built. The foundation and walls are built up with 

 small twigs, rootlets, weed stalks, strips of inner bark and other 

 plant fibers, mixed with bits of string, rags, or dry leaves; the sides 

 and rim are often decorated with feathers, dry blossoms of the sage, 

 or the dry flower clusters of other plants; and the inner cavity is 

 lined with finer rootlets, fine grass, and perhaps a few small feathers ; 

 some nests are profusely lined with the cottony seeds of the cotton- 

 wood. 



One shallow nest that I measured, taken from a sycamore in the 

 Huachuca Mountains, measured externally 1% to 2 inches in height, 

 and 5 to 6 inches in diameter ; the inner cavity was Zy2 by 4 inches 

 in diameter and 1% inches deep. 



Eggs. — Three or four eggs are most commonl}' laid by Cassin's 

 kingbird, though quite often the set consists of five and very rarely 

 as few as two. The eggs resemble those of other kingbirds, though 

 they are as a rule less heavily spotted. They are about ovate and 

 are only slightly glossy. The ground color is white or creamy white. 

 The markings, often grouped about the larger end, are small spots or 

 dots of various browns, "chestnut-brown," "dark vinaceous-brown," 

 or "light brownish drab," often, but not always, mixed with under- 

 lying spots of "Quaker drab" or shades of pale lavender. The 

 measurements of 50 eggs average 23.5 by 17.4 millimeters; the eggs 

 showing the four extremes measure 27.9 by 19.3, 21.8 by 17.3, and 

 22.6 by 16.3 millimeters. 



Young. — Bendire (1895) says that incubation "lasts from twelve 

 to fourteen days, and is almost always, if not exclusively, performed 

 by the female. I have never noticed the male on the nest." Both 

 sexes, however, assist in the defense and care of the young. Mrs. 

 Wheelock (1904) says that the young remain in the nest about two 

 weeks. In the southern portion of its range, the Cassin's kingbird 

 is said to raise two broods in a season. 



Plumages. — The young kingbirds are hatched naked, but the 

 Juvenal plumage soon appears and is well developed, except for the 

 shorter wings and tail, by the time the young bird leaves the nest. 

 The fully developed juvenal plumage is much like that of the adult 

 female, but the plumage is of looser texture and all the colors are 

 duller; the sexes are alike; the head, neck, and breast are a lighter 

 gray, the yellow of the abdomen is paler, and the back is more gray- 



