FAMILY ACCIPITRIDAE 25I 



the trunk of a huge tree about 35 meters (111 feet) from the ground. 

 It was made of large sticks and was lined with the hair of sloths. 

 A fresh egg taken here on April 27, white without markings, al- 

 though badly nest stained, measured "2.80x2.35 inches, or 71.12 x 

 69.9 mm." (The final figure should be corrected to 59.69, which is the 

 equivalent of 2.35 inches.) On a second visit, on May 9, another 

 egg, with incubation begun, was secured that measured "76.71 X 

 57.15 mm." This also was stained, but Norris believed that it was 

 marked also with blotches of light brown. Fowler and Cope (I.e., 

 pp. 260, 262) describe two nests examined in British Guiana built in 

 forks in tall silk-cotton trees. They were bulky structures from 1.2 to 

 1.3 meters in diam.eter placed at about 40 meters from the ground, 

 above the level of the surrounding forest canopy. 



Five eggs in the U. S. National Museum were laid by a captive 

 bird at the National Zoological Park between 1946 and 1951, 4 

 in the month of July and 1 in August. These are white, somewhat 

 nest-stained (but without markings) with a finely granulated shell. 

 They are short subelliptical to nearly elliptical in shape and measure 

 as follows: 73.4x60.5, 77.4x62.2, 78.0x62.1, 78.0x62.3, and 

 78.1x60.2 mm. 



This species is often called aguilucho. 



CIRCUS CYANEUS EUDSONIUS (Linnaeus): Marsh Hawk; 

 Gavilan Sabanero 



Figure 45 



Falco hudsonius Linnaeus, Syst. Nat., ed. 12, vol. 1, 1766, p. 128. (Hudson Bay.) 



Marsh hawks, in any plum.age, are distinguished from all others 

 of the family by the small but distinct semicircular ruff of feathers 

 with decurved tips that extends from the sides of the base of 

 the head forward and around across the lower throat ; and by the 

 white patch on the lower rump and upper tail coverts, prominent 

 when the birds are in flight. 



Description. — Length, 450 to 530 mm. Adult male, upper surface, 

 throat, and upper breast pale gray, washed above more or less with 

 brown to produce indefinite streaks on crown and hindneck; rest of 

 under surface white, barred indefinitely with gray on upper breast, 

 and barred and spotted lightly with cinnamon elsewhere ; tips of 

 flight feathers black; rest of under wing surface white, barred and 

 spotted lightly with gray ; rump and upper tail coverts white ; tail 

 gray, barred rather indefinitely with grayish brown. 



Adult female, fuscous-brown above, with feathers of crown, hind- 

 neck, back, and wing coverts edged with buffy brown to cinnamon; 



