BIRDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 305 



in this arid region were not suited to them, so that their number was 

 not great. 



MACHETORNIS RIXOSA RIXOSA (Vieillot) 



Tyranmis rixosus Vieillot, Nouv. Diet. Hist. Nat., vol. 35, 1819, p. 85. 

 (Paraguay.) 



Common and widely distributed through the pampas and the 

 Chaco, the present bird was noted at the following points : Berazate- 

 gui, Buenos Aires, June 29, 1920; Santa Fe, Santa Fe, July 4; Ee- 

 sistencia, Chaco, July 9 and 10; Las Palmas, Chaco, July 14 to 23; 

 Formosa, Formosa, August 5, 23, and 24; Riacho Pilaga, Formosa, 

 August 21; Puerto Pinasco, Paraguay, September 1 and 30; Kilo- 

 meter 80, Avest of Puerto Pinasco, September 6 to 21 ; Lavalle, Buenos 

 Aires, October 23 and November 9; Montevideo, Uruguay, January 

 14, 1921 ; La Paloma, Uruguay, January 23 ; San Vicente, Uruguay, 

 January 27 to Februai-y 2 ; Lazcano, Uruguay, February 5 to 9. 

 The sj^ecies was most abundant in the Chaco, and was not recorded 

 in the arid interior sections of central Argentina. An adult female 

 taken at Formosa, AugTist 24, and a pair secured at the Estancia 

 Los Yngleses, Lavalle, Buenos Aires, on Novemb r 9, resemble other 

 skins examined from Paraguay and southern Brazil. 31. r. flavogu- 

 laris Todd.^^ named from Venezuela, of which I have seen no speci- 

 mens, is said to be brighter below than rixosa, with the throat but 

 little paler than the abdomen, while the gray crown is duller, con- 

 trasting less strongly with the back. This form is said to occupy 

 all the northern portion of South America. 



These flycatchers inhabit wet localities in open regions, where 

 occasional trees offer suitable night roosting places, a predilection 

 that explains their greater abundance in the Chaco, where wet 

 savannas with scattered trees are the characteristic feature of the 

 country. Machetornis, though it roosts at night among leafy 

 branches, spends most of its day on the ground, preferably near or 

 among horses, cattle^ ov sheep that it follows as assiduously as do 

 cowbirds for the sake of insects frightened up or attracted by the 

 feeding stock. It is common to find Molothrus and Machetornis in 

 company in suitable situations, and the flycatcher flies up to perch 

 on the back of an ox or a horse as fearlessly as on a log or a post. 

 In fact, the birds shoAved preference for such perches and frequently 

 alighted on an animal when frightened from the ground. The ordi- 

 nary method of progression of this bird was peculiar. A long, 

 hesitating step made with bobbing head, was followed by a run for 

 four or five steps, then another long step with the run repeated. In 

 pursuit of insects or to evade too familiar approach it often ran 



8* Ann. Carnegie Mus., vol. 8, May 20, 1912, p. 210. (Tocuyo, Estado Lara, Venezuela.) 



