ANDERSON — THE BIRDS OF IOWA. 299 



rushes, weeds and wild rice along creeks and sloug-hs, departing 

 for the south about the middle of September. 



Genus Molutiirus Swainson. 



213. (495). Mohd/irus ater {Y^odA.). Cowbird. 



The Cowbird is an abundant summer resident in all parts of the 

 state, arriving about the middle of April and remaining until the 

 latter part of October. A few birds sometimes remain through- 

 out the winter in southern Iowa. The Cowbird is the onl}' Iowa 

 bird which is habituall}' and notoriously parasitic, never building 

 a nest of its own and depositing its eggs in the nests of other, 

 usually smaller, birds. The eggs are generally laid before the 

 owner of the nest has completed laying, and as the Cowbird' s e^^g 

 hatches in about ten days, sooner than those of most birds, the 

 rightful owner's offspring are often crushed to death and crowded 

 from the nest. Most birds do not seem to mind the imposition 

 and I have seen a tiny Warbler busily feeding a young Cowbird 

 twice as large as herself, after it has left the nest. I have found 

 a number of nests of the Yellow Warbler in which a second story 

 has been added to the nest after a Cowbird's e:gg has been laid, 

 imbedding it in the bottom of the nest. This is not done if the 

 Warbler has laid any of her own eggs. W. A. Bryan has also 

 found a Traill Flycatcher's nest with a Co-wbird's egg imbedded. 



In "Observations on the Cowbird" (Iowa Orn., iii, 1897, pp. 

 4-7), David L. Savage reports the finding of eggs from April 22 to 

 July 27, nests containing from one to five Cowbird's eggs. He 

 notes twenty species which are imposed upon, viz.: Robin, Tow- 

 hee. Vesper Sparrow-, Chipping Sparrow, Field Sparrow, Blue- 

 gray Gnatcatcher, Blue-winged Warbler, Yellow Warbler, Worm- 

 eating Warbler, Baltimore Oriole, Orchard Oriole, Pewee, King- 

 bird, Red-eyed Vireo, Wood Thrush, Indigo Bird, Scarlet Tana- 

 ger, Prairie Horned Lark, Yellow-breasted Chat, Water Thrush, 

 Western Yellow-throat, Ovenbird, Meadow Lark, Rose-breasted 

 Grosbeak, and Redstart. The Field Sparrow and the Indigo 

 Bird were most imposed upon, and the Kingbird was the only 

 species that objected. Other observers in Iowa have reported the 

 Bluebird, Brown Thrasher, Warbling Vireo, Bobolink, and Barn 

 Swallow, and I have noted in addition the Red-winged Blackbird, 

 Least Flycatcher, Traill Flycatcher, Yellow-throated Vireo, and 



