108 BULLETIN 133^ UNITED STATES NATIONAL MUSEUM 



a tall tree to a perch above the surrounding leaves and peered about, 

 giving a note resembling whaow in a drawn-out nasal tone. In 

 Guarani the species was called taguatoi. 



Both birds taken are males, one in full plumage, and the other in 

 process of molt from a lighter, immature dress. This second bird 

 has the throat white, and is lighter, less distinctly marked below than 

 the adult. The second specimen, when first killed, had the maxilla 

 and tip of the mandible black; remainder of mandible and a spot 

 on the maxilla below the nostril glaucous-graj'^ ; iris marguerite yel- 

 low; cere deep neutral gray; tarsus and toes carnelian red; nails 

 black. 



CIRCUS CINEREUS Vieillot 



Circus cinereus Vieillot, Nouv. Diet. Hist. Nat., vol. 4, 1816, p. 454. (Para- 

 guay and Rio de la Plata.) 



The small marsh hawk was recorded only near Lavalle, Buenos 

 Aires, where at the Estancia Los Yngleses on October 29, 1920, I 

 secured a male as it came sailing across a marsh with several 

 Agelaius thilius in hot protest of its passage. This specimen, 

 hatched apparently the previous summer, is in brown immature 

 plumage save for one or two gray clouded feathers in the dorsal 

 region, and a grayish wash on some of the primaries. In life the 

 tip of the bill was dull black; base of maxilla light Payne's gray; 

 base of mandibular rami, gape, and cere light olive yellow, chang- 

 ing laterally on the cere to asphodel green ; iris pale pinard yellow ; 

 tarsus primuline yellow; claws black. 



Near the coast below Cape San Antonio in this same region I 

 found a pair that evidently nested somewhere near at hand in the 

 rush-covered marshes that here alternated with sand dunes. The 

 male, an adult bird in full plumage, that appeared very light in 

 color on the wing, was taken November 6. This species is similar in 

 appearance and manner of hunting to the North American marsh 

 hawk and has the same light graceful soaring flight that enables 

 it to scan the grass closely in its search for food. 



CIRCUS BUFFONI (Gmelin) 



Falco 'buffoni Gmelin, Syst. Nat., vol. 1, pt. 1, 178S, p. 277. (Cayenne.) 



Of two specimens (both males) of this marsh hawk taken, one 

 was secured at Las Palmas, Chaco, on July 26, 1920, and the second 

 at the Riacho Pilagu, Formosa, on August 15. The first of these 

 was an adult bird in full dark plumage, with sexual organs one- 

 fourth developed. The breast and neck are entirely black save for an 

 obscure white patch on the chin and partly concealed white markings 

 on the ruff and upper breast, while the abdomen varies from russet to 

 mars brown, and the thighs and flanks are nearly black. Feathers 



