204 U.S. NATIONAL MUSEUM BULLETIN 233 



To the previously listed fosterers of the small, northern race of the 

 cowbird, M.h. minimus, the following are added, bringing the total up 

 to 34 forms. This race is extending its range in the West Indian area, 

 an expansion which brings it into contact with new potential hosts. 



Troglodytes musculus tobagensis Law- Icterus bonana (Linnaeus) 

 rence Icterus chrysocephalus (Linnaeus) 



Dacnis cayana cayana (Linnaeus) Icterus jamacaii croconotus (Wagler) 



Dendroica petachia ruficapilla (Gmelin) 



Macroagelaius stibalaris imthurmi 

 (Sclater) 



Two additions to the hosts of the Venezuelan race of the shiny 

 cowbird, M.b. venezuelenis, are here recorded, bringing its known 

 fosterers to a total of 10. 



Holoquiscalus lugubris (Swainson) Icterus nigrogularis nigrogularis (Hahn) 



Single records of two additional hosts of the large Colombian race 

 of the parasite, M.h. cabanisii have come to my attention, bringing its 

 known hosts up to 8 forms. 



Icterus chrysater giraudii Cassin Tachyphonus rufus (Boddaert) 



In the following catalog the pertinent data are given for these 

 additional hosts and also new data on previously listed hosts in cases 

 where the information appreciably alters our understanding and our 

 earlier summation. 



Stripe-crowned Spinetail 



Cranioleuca pyrrhophia (Vieillot) 



This spinetail recently has been added to the known hosts of the 

 shiny cowbird in the Province of Salta, northwestern Argentina, 

 by Gunnar Hoy, to whom I am indebted for the information. The 

 nominate races of both host and parasite are involved in this record. 



Baer's Spinetail 



Asthenes baeri (Berlepsch) 



The first records of this spinetail as a host of the shiny cowbird 

 only recently have come to my attention — all of them from parasitized 

 nests found near Salta, northwestern Ai^gentina, by Gunnar Hoy, 

 according to Dr. Johann Ottow (in htt., 1961). The nominate race 

 of host and of parasite are involved here. Further details, received 

 directly from Hoy, indicate that this bird is rather frequently vic- 

 timized and that as many as 3 cowbird eggs have been found in 

 one nest. Hoy found that the host usually accepted and incubated 

 the parasitic eggs. "As usual, the Asthenes would not forsake the 

 nest for an egg or two of the cowbird. In some cases it would incubate 

 even three, but I never saw it incubate four." 



