ICTERID^ — THE ORIOLES. 155 



of characters for two races. The extremes of size in this species are as 

 follows : — 



Largest. (11,271, $, Fort Bridger.) Wing, 4.G0 ; tail, 3.35; culmen, .72; tarsus, 1.03. 

 yS'ma??es<. (17,297, (J, Mira Flores, L. C.) " 3.80; " 2.65; " .60; " .84. 



Habits. The common Cow Blackbird has a very extended distribution 

 from the Atlantic to California, and from Texas to Canada, and probably to 

 regions still farther north. They have not been traced to the Pacific coast, 

 though abundant on that of the Atlantic. Dr. Cooper thinks that a few 

 winter in the Colorado Valley, and probably also in the San Joaquin Valley. 



This species is at all times gregarious and polygamous, never mating, and 

 never exhibiting any signs of either conjugal or parental affections. Like 

 the Cuckoos of Europe, our Cow Blackbird never constructs a nest of her 

 own, and never hatches out or attempts to rear her own offspring, but im- 

 poses her eggs upon other birds ; and most of these, either unconscious of the 

 imposition or unable to rid themselves of the alien, sit upon and hatch the 

 stranger, and in so doing virtually destroy their own offspring, — for the 

 eggs of the Cowbird are the first hatched, usually two days before the others. 

 . The nursling is much larger in size, filling up a large portion of the nest, 

 and is insatiable in its appetite, always clamoring to be fed, and receiving 

 by far the larger share of the food brought to the nest ; its foster-companions, 

 either starved or stifled, soon die, and their dead bodies are removed, it is 

 supposed, by their parents. Tliey are never found near the nest, as they 

 would be if the young Cow Blackbird expelled them as does the Cuckoo ; 

 indeed, Mr. Nuttall has seen parent birds removing the dead young to a 

 distance from the nest, and there dropping them. 



For the most part the Cowbird deposits her egg in the nest of a bird much 

 smaller than herself, but this is not always the case. I have known of their 

 eggs having been found in the nests of Turdus mustelinus and T. fuscescens, 

 Sturnella ma(jna and S. ncglecta. In each instance they had been incubated. 

 How the young Cowbird generally fares when hatched in the nests of birds 

 of equal or larger size, and the fate of the foster-nurslings, is an interesting 

 subject for investigation. Mr. J. A. Allen saw, in Western Iowa, a female 

 Harporhynchus onifus feeding a nearly full grown Cowbird, — a very inter- 

 esting fact, and the only evidence we now have that these birds are reared 

 by birds of superior size. 



It lays also in the nests of the common Catbird, but the egg never remains 

 there long after the owner of the nest becomes aware of the intrusion. The 

 list of the birds in whose nests the Cow Blackbird deposits her egg and it is 

 reared is very large. The most common nurses of these foundlings in New 

 England are Spizclla socialis, JEmpidonax minimus, Gcothlypis triclias, and all 

 our eastern Vireos, namely, olivaceus, solitarius, noveboracensis, gilviis, and 

 flavifrons. Besides these, I have found their eggs in the nests of Polioptila 

 ccerulea, Mniotilta varia, Helminthopliaga rnjicapilla, Dcndroica vircns, D. 



