206 U.S. NATIONAL MUSEUM BULLETIN 233 



tendency to throw out the parasitic eggs. Prior to Hoy's observations, 

 this flycatcher had been noted as a cowbird victim a few times in the 

 province of Tucuman, not very far to the south of Salta. The nom- 

 inate race of host and of parasite are involved in both cases. 



Short-tailed Ground-tyrant 



Muscigralla brevicauda Lafresnaye and D'Orbigny 



This bird was not known to be imposed upon by the shiny cowbird 

 until very recently, when Marchant (1958, p. 384; 1960, pp. 372, 584) 

 listed it as a host of the Ecuadorian race of the parasite M.b. aequator- 

 ialis in the Santa Elena peninsula of southwestern Ecuador. Out of 

 36 nests observed, only a single case of parasitism was noted. In 

 this nest there were three young cowbirds. 



Fork -tailed Flycatcher 



Muscivora tyrannus (Linnaeus) 



Known as a frequently used fosterer of the nominate form of the 

 shiny cowbird in Argentina, the fork-tailed flycatcher has now been 

 noted in a similar capacity in eastern Brazil, where Chagas (in litt.) 

 found it to be parasitized in the state of Minas Geraes. All the 

 records have to do with the nominate race of the fork-tailed flycatcher. 



In a study of Venezuelan birds, Friedmann and Smith (1955, p. 507) 

 pointed out how surprisingly little has been published on the nesting 

 of this wide-ranging flycatcher other than in the Argentine habitat of 

 its nominate race. Such a situation probably accounts for the ab- 

 sence of records of cowbird parasitism in the more northern parts of 

 its range; it is very unlikely that the fork-tailed flycatcher is left 

 unmolested by the shiny cowbird in these regions. 



Kiskadee Flycatcher 



Pitangus sulphuratus (Linnaeus) 



To the few previously noted records from Argentina may be added 

 the report by Harrison (1950, p. 6) that he found a "substantial" 

 nmnber of victimized nests in Uruguay. On geographic grounds, 

 these Uruguayan records refer to the subspecies bolivianus of the host. 

 Recently, in the state of Minas Geras, Brazil, Chagas (in litt.) 

 has found that the subspecies maximiliani is also victimized by the 

 shiny cowbird. The nominate race, M.b. bonariensis, is involved in 

 all of these cases. 



Superciliated Wren 



Thryothorus superciliaris (Lawrence) 



In the Santa Elena peninsula of southwestern Ecuador, Marchant 

 (1960, pp. 377, 585) found that the superciUated wren was victimized 

 frequently by the shiny cowbird (subspecies M.b. aequatorialis) . Of 



