6 



ORNITHOLOGIST 



[Vol. 15-No. 1 



isfied that tliis egg was the first of the clutch, 

 a view which was strengthened by the dis- 

 covery of a second egg just twenty-eight hours 

 after the first one was seen. The second egg 

 was deposited like the first upon the fioor of the 

 cage, but quite at the otlier end of her prison. 

 A nest of the catbird containing three eggs of 

 that species, was now placed upon the perch 

 and fastened to the wires, and tlie third day 

 of deposition was anxiously looked for, but no 

 addition was seen up to my retiiing hour, 

 thirty-two hours after the second one appeared; 

 but on arising early the next morning, the first 

 of .June, the third egg was found close to the 

 second. On this day the bird refused to eat, 

 and, as bird fanciers express it, looked dump- 

 ish. The morning of June 2d I found the re- 

 mains of a once perfect egg. It appeared to 

 have fallen and been broken. This day the 

 bird died, as I felt convinced, of blood poison- 

 ing, as the wing where it joined the body was 

 in a state of gangrene. Dissection proved that 

 no more eggs were in a state of formation for 

 tliis clutch. All of the eggs were laid within 

 a space of eighty-five hoius. That is from the 

 time the first egg was deposited to the date of 

 the last addition. Many times have I met 

 with nests containing four eggs of the Cowbird 

 besides the eggs of the rightful owner of tlie 

 nest, and have been impressed with tlie idea 

 that the four had been laid by the same bird, 

 so symmetrically exact was the apparent clutch, 

 both in form, size and markings. Only once 

 have I met with five eggs of the Cowbird in 

 one nest, and they were so dissimilar that it 

 was evident at a glance that they were laid by 

 different Cow Buntings. 



In every instance that I have recoi'ded in my 

 note-book, and they are numerous, I have had 

 it impressed upon me that the Cowbird is in- 

 fiuenced by the size of the nest in laying a 

 large number of eggs in one nest, rather than 

 by tlie juimber of eggs to be laid by tlie legiti- 

 mate owner. Of course what we term instinct 

 in tlie lower animals asserts itself in some way 

 in tliese cases, and the Cowbirds judge as to 

 the ability of tlie contemplated foster parents 

 to provide for the unwelcome nur.slings, by 

 the size of the nest. Once I met with a Blue- 

 bird's nest in a very large excavation, con- 

 taining five blue eggs and four speckled ones, 

 and ill this case the speckled eggs were evi- 

 dently laid by the same female, judging from 

 size and markings. Tliis was in early May, 

 when but few birds are nesting that are im- 

 posed on by tliese parasites. It is not common 

 to find Bluebirds suffering from the persecu- 



tions of Molothrun in Michigan, and rare to 

 find over two alien eggs in a nest of Sialia. 



I am satisfied that the Cowbird is occasion- 

 ally mistaken in laying more than is intended 

 through not identifying the eggs of its own 

 species. This occurs often in the Chewink's 

 case, and that too at a time when tliere is 

 room for all. It is not uncommon to find four 

 eggs of this sycophant in a nest containing 

 three or four Chewink's eggs, and some of the 

 latter would almost exactly resemble some of 

 the former. In the case of the vireos and 

 small warblers it is iniusual to find more than 

 one or two Cowbird' s eggs in a nest, although 

 a Red-eyed Vireo's nest containing four of the 

 interlopers is now before me. 



Third, the subject of this sketch usually 

 selects nests containing one or more eggs of 

 the original architects, although all have met 

 with numerous instances where one, two and 

 three eggs of the Cowbird occupied a nest of 

 some disconsolate pair which had been scared 

 away by the too rapidly accumulating testi- 

 monials without attempting to assert their 

 rights in any way. It is my opinion that in 

 the face of so great a fraud the swindled erst- 

 while householders invariably leave their claim 

 and seek other quarters. The largest number 

 of Cowbird' s' eggs that I liave yet found occu- 

 pying one nest in which the owner had not yet 

 laid was four. The nest was tliat of the 

 Golden-crowned Tlirush. Strange to say, al- 

 though the female was sliot near at liand, 

 there were no legitimate eggs lying outside of 

 the nest, as is often the case, particularly witli 

 the Chewink and some of the larger birds. 

 More singular still is the fact that the eggs 

 which were uniform in size, etc., were incu- 

 bated eijually to about the fifth or sixth day. 



Is the f -owbird ]>olygamous? We frequently 

 see it described so, but as yet there is no proof 

 positive. In my (qiiniou it may with equal 

 propriety be called polyandrus. It is, how- 

 ever, reasonable to suppose that the birds pair 

 at the beginning of the season, and remain 

 faitlifiil to each other at least during spring 

 and summer. 



Are the birds of this species as secret in 

 their invasions of other birds' nests as is gen- 

 erally considered'.' From ac^tious observed by 

 me, I am satisfied that tlie legitimate owner of 

 the house is often driven from tlie nest by the 

 male ("owbird to allow the female an oppor- 

 tunity to occupy the same, but in the large 

 majority of cases the alien eggs are surrep- 

 titiously deposited duiiug absence of rightful 

 owner. 



