HOST RELATIONS OF PARASITIC COWBIRDS 219 



merely examines specimens of the three, the giant species would 

 certainly be looked upon as a climax development and not as an 

 intermediate one. Ethologically and geographically, the data are 

 more readily arranged with the giant form in the middle. 



In keeping with its large size, the giant cowbird parasitizes large 

 hosts. Although it occurs over a vast range and is not a rare bird in 

 many areas, Psomocolax remains a very inadequately studied species. 

 Indeed, since my 1929 account, little really new or significant informa- 

 tion has been added to our knowledge of its breeding habits. However, 

 Belcher and Smooker (1937, pp. 525-526), Skutch (1954, pp. 316-320), 

 Tashian (1957, pp. 87-97), Schafer (1957, pp. 135-138), and Lehmann 

 (1960, pp. 272-273) have added welcome supplementary observations 

 on its habits in Trinidad, in Central America, in Venezuela, and in 

 C'Olombia. 



Seven species have been recorded as hosts of the giant cowbird, 

 four of which are listed in my earlier account. 



green jay, Cyanocorax yncas green oropendola, Xanthornus viridis 



(Boddaert) (P. L. S. Muller) 



Wagler's oropendola, Zarhynchus yellow-rumped cacique, Cacicus cela 



loagleri (Gray and Mitchell) (Linnaeus) * 



Montezuma oropendola, Gymnostinops red-rumped cacique, Cacicus 



montezuma (Lesson) haemorrhous (Linnaeus), 

 crested oropendola, Xanthornus 



decunianus Pallas 



• Cacicus persicus, previously listed as a host, Is now considered to be a synonym of C. cela. 



The recent addition of so unexpected a bird as the green jay to the 

 known hosts by Lehmann (1960, p. 273) can only be looked upon, 

 in light of cm-rent knowledge, as an unusual host choice. The green 

 jay makes an open, saucer-shaped nest of twigs and rootlets, often 

 placed in the denser portions of the foliage of the trees in which they 

 are built, a very different type of nest from the long, conspicuous, 

 pendant nests of the oropendolas. 



Lehmann watched a pair of these jays attending and feeding a re- 

 cently fledged giant cowbird in August 1957, at Cajibio, Cauca, 

 Colombia. He observed these three birds together repeatedly on 

 several mornings as they came to feed in his garden. No young jays 

 were seen with them. The fact that the observation was of some 

 duration indicates that it was a real foster parent-young relationship. 

 (If it had been a single casual observation, the possibility would have 

 remained that the young parasite might not actually have been reared 

 by the jays but that it had begged for food from them and had suc- 

 ceeded in obtaining their temporary response and attention. Such 

 occurrences are known to happen not infrequently with the smaller 

 cowbirds and even with fledglings of non-paras ti tic species.) 



