THE COWBIRDS. 61 9 



tliat most of these birds were yoiiiio-, liatclied late in the season^ 

 from their incessant strident hnnger notes. I lirst observed them about 

 the middle of March. A week ago, while riding- past the meadow where 

 they were feeding, I noticed among them 3 individuals with ])urple 

 S])ots ou their plumage. They were at a distance from me, and I 

 naturally concluded that they were young common Cowbiids {M. bona- 

 riensis) casually associating with the Bay wings. I was suriirised to 

 see them, for the young nuile M. honurioisis always acquires the pur- 

 ple plumage before March, so that these individuids were changing 

 color five weeks after the usual time. To-day, while out with my gnu, 

 I came upon the flock, and noticed 4 of the birds assuming the purple 

 plumage, 2 of them being almost entirely that color; but I also noticed 

 with astonishment that they had bay or chestnut-colored wings, also 

 that those with least purple on them were marvelously like the Bay- 

 wings in the mouse colored plumage of the body and the dark tail. I 

 had seen these birds before the pur[)le plumage was acquired, and there 

 was then not the slightest difference amongst them, the adults and their 

 supposed offspring being alike; now some of them appeared to be under- 

 going the process of a transmutation into another species. I at once 

 shot the 4 spotted birds, along with 2 genuine Bay-wings, and wa& 

 delighted to find that the first were young Screaming Cowbirds. 



I must now believe that the extra eggs twice found in the nest of the 

 Bay-wings were those of the Screaming Cowbird ; that the latter species 

 lays chiefly in the nests of the former; that the eggs of the two species 

 are identical in form, size, and color, each bird also laying 5; and that, 

 stranger still, the similarity is as perfect in the young birds as it is in 

 the eggs. 



Ap7'il 15. — This morning I started in quest of the Bay-wings, and 

 observed 1 individual, that had somehow escaped detection the day 

 before, assuming the purjde dress. This bird 1 shot; and after the 

 flock had resettled a short distance oft" I crept close u]) to them, under 

 the shelter of a hedge, to observe them more narrowly. One of the 

 adults was closely attended by 3 young birds; and these all, while I 

 watched them, fluttered their wings and clamored for food every time 

 the old bird stirred on its perch. The 3 young birds seemed pre- 

 cisely alike; but presently I noticed that 1 of them had a few minute 

 purple spots, and on shooting this one I found it to be a young ]\L 

 rnfoaxillaris, while the other 2 were true young Bay-wings. 



The hungry cry of the young M. hadius (Bay-wing) is quite different 

 from that of the young M. l)on((Hensis. The cry of the latter is a long\ 

 shrill, two-syllabled note, the last syllable being prolonged into a con- 

 tinuous squeal when the foster ])arent ajiproaches with food. The cry 

 of the young ^^. baditis is short, reedy, tremulous, and uninflected. The 

 resemblance of the young M. rufoaxillans to its foster brothers in 

 language and idumage is the more remarkable when we reflect that the 

 adult bird m its habits, gestures, guttural notes, also in its deep purple 

 l)lumage, comes much nearer to M. bonariensis than to 21. baditis. It 



