144 U. S. NATIONAL MUSEUM BULLETIN 211 



the redwings will continue to build new nests and make repeated 

 attempts to raise their broods until well into midsummer, when their 

 reproductive urge wanes. 



Friedmann (1929) calls the redwing "a fairly common but rather 

 local victim" of the cowbird. At Ithaca, Allen (1914) found hun- 

 dreds of nests but never any cowbirds' eggs. On the other hand, 

 Walter A. Goelitz (1916), of Ravina, 111., writes: "Until this year I 

 have never found the eggs of this bird in Red-wing nests, but in a 

 little colony of some twenty-five pairs of Red-wing Blackbirds, I 

 destroyed eleven Cowbird eggs on June 17th and six on June 27th of 

 the present season." 



Robert H. Wolcott (1899) never saw a cowbird's egg in a redwing's 

 nest during his collecting in Michigan, but found it not unusual in 

 Nebraska. He says: "The owners of the nest, in case eggs of their 

 own have already been deposited, apparently peck holes in all, in- 

 cluding that of the intruder, and desert the nest. But in one instance 

 a nest was found where the single, still fresh Cowbird's egg which it 

 contained had been almost entirely buried beneath a new floor, and 

 above this were four Blackbird's eggs." 



Out of hundreds of nests, found at Buckeye Lake, Ohio, by Milton 

 B. Trau tman (1940), "a Cowbird's egg was found in each of 4 nests. 

 These nests were isolated. Apparently, it was sometimes possible 

 for a Cowbird to lay its egg in a solitary nest without discovery, 

 whereas if it attempted to lay an egg in a nest in a colony, it was 

 driven away. Once eggs were in the nests the Cowbird was not toler- 

 ated about the nesting colonies." 



Redwings are afflicted with a number of external and internal 

 parasites; Allen (1914) lists four species of Acarina and three of 

 Mallophaga; and Harold S. Peters (1936) names three species of lice, 

 one fly, three mites, and two ticks that infest the eastern redwing. 



In spite of their many enemies, some redwings seem to live for a 

 reasonable number of years. From his study of banding records on 

 Cape Cod, Mass., Packard (1937) has this to say about longevity: 

 "Averages compiled from the 266 returns show that 16 percent of the 

 total number of Red-wings banded survived one year, 7 percent two 

 years, 4 percent three years, 2 percent four years, and 0.3 percent 

 five years after banding." This takes no account of any survivors 

 that did not return to the traps; and the ages of banded birds is not 

 always known. He continues: "The oldest males in the records are 

 two banded as adults in April 1931, and taken yearly through 1936. 

 As it requires at least two years to attain to adult plumage, these 

 birds were hatched in 1929, or earlier, thus being at least seven years 

 old. Several females lived five years after banding." Banding rec- 

 ords published by May Thacher Cooke (1937) show that 6 redwings 



