6 Iowa Ornithologist. 



The female Cowbird prepares to find a nest that is just completed and 

 as yet has none of the owners eggs in ; here the intruder deposits her egg 

 with confidence that it will hatch first, as ten days will hatch her egg, while 

 twelve or fourteen is required for most eggs of Passeres birds. 



If the Cowbird finds it necessary to lay her egg in a nest with other eggs, 

 she often rolls one of the owner's out so that when the mistress returns 

 there will still be the same number of eggs, and probably the exchange will 

 not be noticed. This species has httle preference as to the location of the 

 nests in which to deposit her eggs. I have found them from a Prairie Horned 

 Lark's nest, placed by a hill of corn, and a Pewee's nest, on a shelf in an 

 old vacant house, the only entrance being a broken pane in a window, to 

 a Blue- gray Gnatcatcher's nest in the depth of the woods and twenty- five feet 

 from the ground. 



Of the forty-six nests before spoken of, fourteen were placed on the 

 ground, ten within two feet of the ground, ten between two and ten feet, and 

 twelve more than ten feet from the ground. I have found twenty-five species 

 imposed upon by the Cowbird: i. e., Robin, Towhee, Vesper Sparrow, 

 Chipping Sparrow, Field Sparrow, Blue-gray Gnatcatcher, Blue-winged 

 Warbler, Yellow Warbler, Worm- eating Warbler, Baltimore Oriole, Orchard 

 Oriole, Pewee, Kingbird, Red-eyed Vireo, Wood Thrush, Indigo bird. Scarlet 

 Tanager, Prairie Horned Lark, Yellow-breasted Chat, Water Thrush, Western 

 Yellow-throat, Oven bird. Meadow Lark, Rose-breasted Grosbeak, and 

 Redstart. The Field Sparrow and Indigo bird are the species that I have 

 found to be most imposed upon by this imposter, possibly because they are 

 the most plentiful of the small birds nesting in my locality. 



The only species that has come under my observations which objected 

 to the Cowbird's egg in its nest was the notorious Kingbird. 



For a week I made daily visits to an old orchard where a pair of Kingbirds 

 had their nest in one of the old apple trees. I saw the last material brought 

 which completed the home and counted the eggs, one, two, three, but on the 

 morning when I expected to find the fourth when I approached the tree I saw 

 that a stranger was on the nest ; I cannot say whether I or the stranger saw the 

 other first. Nevertheless lady Cowbird made short work of slipping off the 

 nest and reaching the nearest woodland, she not even paused to give me a 

 morning salutation as the Kingbird was in the habit of doing. Climbing to 

 the nest, I found three of the Kingbird's eggs and one of the Cowbird's. 



Returning in about an hour to see how matters were at the Kingbird 

 home, the female was on the nest and all seemed quiet ; but lo, the poor Cow- 

 bird egg was not in the nest, nor under the nest, nor could I find it anywhere. 

 Undoubtedly master Kingbird had removed it. He would not allow his beloved 

 mate to be converted into a foster parent. 



I have never found a double nest of any of our birds where the owner 

 had built an addition to her nest to cover the Cowbird's egg, although 

 some writers say that this is often done. 



A few words about the great variation in the eggs of this species. Of 

 twenty- five eggs in my collection, the average size is .86 x .69 inches ; the largest 

 .97 X .78 ;' the smallest .75 X .65. It is a noticeable fact that the eggs of the 



