226 BULLETIN 16 7, UNITED STATES NATIONAL MUSEUM 



Eggs. — The Swainson's hawk lays two to four eggs, usually two. 

 Bendire (1892) says: "About one nest in four contains three eggs, 

 and a set of four is rarely met with. I found but one such in over 

 thirty nests." The eggs vary in shape from short-ovate to oval. The 

 shell is smooth or finely granulated. The ground color is pale bluish 

 or greenish white when fresh, fading to dull white. About one-fifth 

 of them are immaculate or nearly so. Others are irregularly and 

 more or less sparingly spotted with various shades of brown, buff 

 or drab, "chestnut-brown", "cinnamon-brown", "cinnamon", "clay 

 color", or more rarely \\ith shades of "Quaker drab." Very rarely are 

 they heavily marked. The measurements of 166 eggs in the United 

 States National Museum average 56.5 by 44 millimeters; the eggs 

 showing the four extremes measure 62 by 46.5, 60.5 by 47.5, 50 by 

 41, and 53 by 39.5 millimeters. 



Yoimg. — Incubation is shared by both sexes and lasts for about 

 28 days. The young hatch at intervals of a day or two and are 

 bountifully supplied with food by both parents. Mrs. Irene G. 

 Wheelock (1904) says that after the "young are fledged, you may see 

 them jumping with raised wings through the grass in brisk pursuit 

 of crickets and grasshoppers. This they learn to do by imitating the 

 parent, and it is probably their first lesson in pursuing prey. In 

 the nest, they are fed upon small mammals and, even before their 

 down has changed to feathers, they will tear their food with all the 

 ferocity of a young puppy." 



Mr. Cameron (1913) writes: 



The young birds as soon as they were able, sat about in the branches, but re- 

 turned to the nest at night, and also on hot days, during which the parents 

 shaded them. * * * The nestlings have enormous appetites, and consume 

 more in proportion to their size than any other raptorial bird which I have 

 studied or kept in confinement. When hungry they set up a piercing kitten- 

 like cry until they are supplied with food. * * * As observed in this 

 instance, the female buzzard acquired the power of flight in twenty-eight days, 

 and the male only after thirty-five days. 



Plumages. — The downy young, when first hatched, is thickly cov- 

 ered with white down with a slight yellowish tinge. The down 

 becomes whiter with advancing age. The ju venal plumage is ac- 

 quired in about the same sequence as in other 3'^oung Buteos; in a 

 half-grown nestling the throat, neck, center of the breast, the flanks, 

 tibiae, and rump are still downy, while the rest of the plumage is 

 well developed. In this fresh juvenal plumage the upper parts are 

 "warm sepia", broadly edged with "cinnamon" or "pinkish buff"; 

 the tail is "hair brown" or "fuscous", banded with black, with a 

 broad, subterminal black band and with whitish tips ; the breast and 

 tibiae vary from "ochraceous-tawny" to "cinnamon-buff", with hastate 

 or sagittate spots of "warm sepia." This plumage is worn through- 



