BIEDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 109 



of the lower abdomen and under tail coverts are marked or tipped 

 obscurely with white. The second specimen is an immature bird 

 in process of molt from the first year plumage : On the dorsal sur- 

 face new, nearly black feathers are appearing. Below, the breast 

 and abdomen are dirty white, with more or less streaking of fus- 

 cous. It appears that three years at least may be required to gain 

 the full adult plumage, since the new feathers growing in on the 

 back in this individual are obscurely margined with rusty, a char- 

 acter absent in the fully adult bird. The plumages and plumage 

 change in this hawk are of considerable interest, but can be studied 

 successfully only with a considerable series. Apparently the species 

 is dimorphic since light or dark individuals are found in the young 

 stages. 



This beautiful hawk inhabited the open savannas of the Chaco, 

 or the extensive marshes of the pampas. Almost invariablj^ it was 

 seen skimming in true harrier style along the borders of channels 

 or lagoons where it might hope to encounter prey, its large size 

 serving to distinguish it from C. cinereus found in the same regions. 

 The dark plumaged adults were especially handsome, their colora- 

 tion being frequently visible at a considerable distance. 



The species was found at a number of points, but was more 

 common in the Chaco than elsewhere, as will be observed in the 

 folloAving records: Las Palmas, Chaco, July 26 and 31, 1920; 

 Eiacho Pilaga, Formosa, August 15 and 17; Kilometer 182 to For- 

 mosa, Formosa, August 21, several; 200 Idlometers west of Puerto 

 Pinasco, Paraguay, September 25, one; Lavalle, Buenos Aires, 

 November 2 and 4; San Vicente, Uruguay, January 31, 1921, and 

 at the Paso Alamo, Arroyo Sarandi, February 2, one; Lazcano, 

 Urugua3% February 3, one. 



The adult male taken had the distal half of the bill black; base 

 gray number seven ; cere vetiver gray ; iris ochraceous tawny ; tarsus 

 and toes light orange-yellow; claws black. 



URUBITINGA URUBITINGA URUBITINGA (Gmelin) 



Falco uriiUtinga Gmelin, Syst. Nat., vol. 1, pt. 1, 17SS, p. 265. (Eastern 

 Brazil.'") 



Near Las Palmas, Chaco, on July 14, 1920, I Idlled a male in im- 

 mature plumage from a tree above a pool of water in heavy forest. 

 This bird was only recently from the nest, as, though in complete 

 plumage, down filaments still clung to some of the rectrices and 

 secondaries. Above it is dark brown, with markings of sayal brown 



^Gmelin writes that the bird was found in Brazil, but Berlepsch and Hartert (Nov. 

 Zool., vol. 9, 1902, p. 113) from the original sources of Gmelin's information have 

 given the type locality as "Bras, or.", eastern Brazil.) 



