THE RED-EYED COWBIRD. 



445 



Hooded Oriole to set on an egg of Callothrus robustus which was on the point of 

 hatching when found. How its own disappeared I can not say. Once two eggs 

 of Callothrus robustus were found in a nest of the small Orchard Oriole" (var. 

 affinis). Twice I have seen a broken egg of Callothrus robustiis under nests of 

 Bullock's Oriole on which the owner was sitting. 



-"Early in June a nest of the Hooded Oriole was found, with four eggs, and 

 one of Callothrus robustiis, all of which I removed, leaving the nest. Happening 

 to pass by it a few days later, I looked in, and to my surprise found two eggs 

 of robustiis, which were broken. These were so unlike that they were probably 

 laid by different birds. Still another egg, and the last, was laid in the same 

 nest within ten days. But the most remarkable instance was a nest of the small 

 Orchard Oriole found June 20, containing three eggs of Callothrus robustus, while 

 just beneath it was a whole eg'g- of this parasite; also a broken one of this and 

 the Dwarf Cowbirds Molothrus obscurus. Two of the eggs in the nest were 

 rotten. The third, strange to say, contained a living embryo. As the nest was 

 certainly deserted, I can only account for this by supposing that the two rotten 

 ones were laid about the first week of June, when there was considerable rain, 

 and that the other was deposited soon after, since which time the weather had 

 been clear and very hot. On one occasion I found a female Callothrus robustus 

 suspended from a nest of the Bullock's Oriole by a stout thread around its neck. 

 The nest contained one young of this Cowbird, and it is probable that its parent, 

 after depositing the egg, became entangled in the tluead on hurriedly leaving 

 the nest, and there died. It had apparently been dead about two weeks. This 

 case supports the view that the eggs or young of the owner are thrown out by 

 the young parasite and not removed by its parent, though I could find no trace 

 of them beneath the nest." 



Among the species imposed on by the Red-eyed Cowbird are the following: 



Milviilusforflcatus, Scissor-tailed Flycatcher. 

 Icterus auduboni, Audubon's Oriole. 

 Icterus cucullatus, Hooded Oriole. 

 Icterus spurius, Orchard Oriole. 

 Icterus bulloclii, Bullock's Oriole. 



Cardinalis cardinalis canicaudus, Gray-tailed 



Cardinal. 

 Guiraca ccerulea eurhyncha, Western Blue 



Grosbeak. 

 Icterus virens longicauda, Long-tailed Chat. 



Other species will undoubtedly have to be addechto this list. 



The Orioles appear to be the special victims of the Red-eyed Cowbird, and 

 among these Audubon's seems to be the worst sufferer. In nine sets of this 

 species in the United States National Museum collection there are only two 

 which contain the normal number of eggs, four. In each of the other seven 

 there are from one to three of those parasitic eggs, with one or two of their 

 owners', and usually some of these are punctured. In none of these nests were 

 eggs of the Dwarf Cowbird found in addition to those of the Callothrus robusfti*. 

 The former appears to deposit its eggs in nests of the smaller Orioles only. 



The eggs of the Red-eyed Cowbird are rather glossy; the shell is finely 

 granulated and strong. Their shape varies from ovate to short and rounded 



