THE OOWBIRD. 



437 



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

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

 five, with perhaps 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 probability laid by the same bird) will be found in one nest. 

 There is so much variation in their eggs, both in size and markings, 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 for those of the parasite, 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 from hatching. I am inclined to attribute this 

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

 throws the eggs of the rightful owner out of the nest purposely to enhance the 

 chances of its off'spring coming to maturity. I have yet to see a punctured Cow- 

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

 by the Cowbird. One would 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 

 Red-headed Woodpecker and the Rock Wren. 



Mr. William Gr. Smith, formerly of Loveland, Colorado, writes me that he 

 found a Cowbird's egg in a Rock Wren's nest, mider 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 whose nests eggs of the Cowbird have 

 been found, and undoubtedly a number of others yet remain to be added to it: 



Zenaidura macroura, Mourning Dove. 



Goccyzus americanus, Yellow-billed Ouckoo. 



Melanerpes erythrocephalus, Eed- headed 

 Woodpecker. 



Tyrannus tyrannus, Kingbird. 



Sayornis phoebe, Phoebe. 



Contopus virens, Wood Pewee. 



Empidonax aeadicus, Arcadian Flycatcher. 



Empidonax pusillus, Little Flycatcher. 



Empidonax pusillus traillii, Traill's Fly- 

 catcher. 



Empidonax minimus, Least Flycatcher. 



Otocoris alpestris praticola, Prairie Horned 

 Lark. 



Dolichonyx oryzivorus. Bobolink. 



Xanthocephalus xanthocephalus, Yellow- 

 lieaded Blackbird. 



Agelaius phceniceus, Eed- winged Blackbird. 



Sturnella magna, Meadow Lark. 



Sturnella magna neglecta. Western Meadow 

 Lark. 



Icterus spurius, Orchard Oriole. 



Icterus galbula, Baltimore Oriole. 



Icterus bullocJci, Bullock's Oriole. 



Scolecophagus cyanooephalus, Brewer's Black- 

 bird. 



Garpodacus purpureus, Purple Finch. 



Spinus tristis, American Grbldfinch. 



Galcarius ornatus, Ghestnut-collared Long- 

 spur. 



Bhynchophanes mccownii, McOown's Long- 

 spur. 



Poocwtes gramineus. Vesper Sparrow. 



