^ THE COWBIRD. 437 



parasitic eggs have been found in a nest, tlie larger numbers usually in those of 

 ground-liuilding- species, especially in that of the Ovenbird, where from three to 

 five, with i)erhaps two or three eggs of the owner, are not especially uncommon. 

 I know of one instance where not less than seven Cowbird's eggs were found in 

 a nest of this species with a single one of its own. Not infrequently two or 

 more eggs (in all probaliilitv laid ])v the same bird) will be found in one nest. 

 There is so inucli variation in their eggs, both in size and inai-kings, that the 

 close resemblance of any two eggs at once attracts attention. It is not unusual 

 to find some of the eggs of the rightful owner thrown out of the nest to make 

 room f )r those of the ])arasite, or to find minute punctures in the shells of some 

 of the remaining eggs. This is possibly done purposely by the Cowbird with 

 her beak or with her sharp claws while sitting on the nest and depositing- her 

 own egg, to keep the eggs froni hatching. I am inclined to attrilnite this 

 puncturing to the latter cause, but there is no doubt tliat tlie Cowbird sometimes 

 thi'ows the eggs of tlie rightful owner out of the nest purposely to enhance the 

 chances of its offspring coming to maturity. I have yet to see a punctured Cow- 

 bird's egg. It is astonishing how many difierent species are thus imposed upon 

 bv the Cowbird. One Avould naturally suppose that birds breeding in holes in 

 trees or under rocks would be exempt from this infliction, but this is not the case. 

 Perhaps among the strangest and most unlikely of foster parents selected are the 

 Ked-headed Wood})ecker and the Rock Wren. 



3Ir. AVilliam CI. 8mitli, formerly of Loveland, Colorado, Avrites me that he 

 found a Cowbird's egy in a Rock Wren's nest, under a ledge of rock, fully 2 

 feet from the entrance, which was barely large enough for the Wren to squeeze 

 through. It seems almost impossible that a bird of this size would be able to 

 enter the small, pendent nest of the Parula Warbler and deposit its egg- therein 

 in the usual way. However, as this species is occasionally imposed on, it is 

 possible that the egg is dropped in the nest with the beak. 



The following is a list of species in Avhose nests eggs of the Cowbird have 

 been found, and midoulitedlv a numl)er of others yet remain to be added to it: 



Zenaidura macroura, Moiiriiinj;' Dove. '■ Af/elaius phceniccufi, Eed- winged Blackbird. 



Coccyzus americanHs, Yellow-billed Cuckoo. 



Mehnierpes erythroccphaliin, Red -headed 

 Woodpecker. 



Tyrannus tyrannm, Kingbird. 



Hayornis phoebe, Phoebe. 



Confopus virens. Wood Pewee. 



Empidonax acadious, Arcadian Flycatcher. 



Empidonax pusilliis, Little Flycatcher. 



Empidonax puHillus traUlii, Tiaill's Fly- 

 catcher. I Spinus trititiii, American (ioldtinch. 



Bw/)J<Zona.r jh/h/w /^s, Least Flycatcher. | Calcarius ornatus, Chestnut-collared Lonj. 



Otocoris ulpoiiria pyoticula, Prairie TToined si)nr. 



Lark. j Rhyitchophanes mccoicnii, McCowu's Lonji 



TMichonyx oryzivorm, Bobolink. ! spur. 



X<n)tho(rphali(K xanflioccphalun, Vcl low- Poocwfes {/raiiiiiicu.s. Vesper Sparrow, 

 lu-adcd Jihukbird. 



Sturnella magna, Meadow Lark. 



SturneUa magna neglecfa, Western Meadow 

 Lark. 



Icterus spurim. Orchard Oriole. 



Icterus galbula, Baltimore Oriole. 



Icterus hiiUocJii, Bullock's Oriole. 



Scolecopliugus cyanocephalus, Brewer's Black- 

 bird. 



Curpodacus purpnrens, Pur]>]e Finch. 



