CONTINENTAL RUSTY BLACKBIRD 293 



tween that and a following low-pitched one. The phrase with the 

 low-pitched final note began with a higher pitched wisslter than that 

 of the other. The 'shuffling' notes, always present in the rusty 

 blackbird's song, seemed more liquid and less rustling, heard at this 

 close range, than I have before considered them. For my own 

 immediate purposes I syllabified the two phrases roughly as oodle-a- 

 wee, eedle-a-woo. The order, however, should probably be reversed, 

 so that a continuous performance might go like this: high-low low- 

 high, high-low low-high, etc. The commas indicate a longer rest 

 than the blanks. If I numbered the eedle-a-woo phrase as 1 and the 

 oodle-a wee phrase as 2, the succession would then be: 1-2, 1-2, 1-2, 

 2, 2, 2, 2, 2, 1-2, 1-2. 



"What is of special interest is the fact, which I observed many 

 times, that the tail was spread with many phrases, but was spread 

 wider with No. 1 than with No. 2. The width of the spread was 

 relative, not absolute." 



Field marks. — The rusty blackbird is not always an easy bird to 

 identify in the field. In spring the migrating flocks may easily be 

 confused with the early flocks of male redwings, for at that time 

 the latter often show little or no red on the wings when perched, 

 and might be mistaken for rusties. The females of the two species 

 are not at all alike, and their habits are different. 



In the fall, the rusty blackbirds deserve their name, as the black 

 plumage of the males and the dark plumage of the females are both 

 more or less veiled with the rusty edgings, and this is much more 

 conspicuous in the younger birds. 



In the Central- Western States, this species is even more difficult 

 to distinguish from Brewer's blackbird. The latter has a thicker 

 bill at the base and a purplish black head, which the rusty does not 

 have. In the fall, the rusty blackbird is much more extensively 

 rusty than is the Brewer's. 



Enemies. — The narrow escape of a terrified rusty blackbird 

 from a sharp-shinned hawk, as related above, shows that these 

 blackbirds recognize the accipitrine hawks and probably the larger 

 falcons as deadly enemies. 



As the rusty blackbird breeds mainly north of the area where cow- 

 birds are abundant, it is seldom imposed upon by these birds, and 

 being larger, would probably not be a very satisfactory foster parent 

 to this parasite. 



Friedmann (1934) reports: "Mr. T. E. Randall found two nests of 

 this bird in Alberta, each with eggs of the Nevada Cowbird. Mr. 

 A. D. Henderson writes me that he found the species victimized in 

 Alberta. These are the first records for this bird as a molothrine 

 victim." 



