384 



THE OOLOGIST 



from the southern part of the state 

 the first week in May. For three or 

 four weeks they flew about the place, 

 the male evidently doing nothing but 

 showing off from the top of a tall 

 dead birch or driving a rival suitor 

 away from his wives, while the fe- 

 males walked around among the cows 

 in the stumpy pastures and fed upon 

 the flies which followed them. 



In the meantime, a pair of Chest- 

 nut-sided Warblers had begun a nest 

 in a raspberry bush in a patch of 

 brush not more than thirty feet from 

 the side of our house, which was then 

 in course of construction. On May 

 31st, this nest was finished and one 

 egg was laid. This I thought was the 

 chance for Mrs. Cowbird. But three 

 days passed, and each day saw an- 

 other egg until four were laid and the 

 set finished, but still no Cowbird's egg. 

 The female warbler sat patiently on 

 these eggs, and could almost be touch- 

 ed before she would leave the nest, 

 until on the morning of June 12th, 

 just nine days after the last egg was 

 laid, when I looked in the nest and 

 saw, not the four young birds which 

 I expected, but one lone Cowbird's 

 egg, which proved to be perfectly 

 fresh. The four Warbler's eggs were 

 on the ground under the nest, two of 

 them punctured. Needless to say, the 

 mother bird was not sitting. 



This was the first time I had ever 

 known a Cowbird to lay an egg in a 

 nest after the full set was completed, 

 to say nothing of when the eggs were 

 ready to hatch, but I was destined to 

 be still more greatly surprised by the 

 only other Cowbird's egg which I 

 found on the place this year. 



I was puzzled to find where this 

 Cowbird was laying the rest of her 

 eggs. There were plenty of fresh 

 nests about the place, and many of 

 them in plain sight, — June 6th, an 

 Qvenbird's nest was found in the 



woods not ten rods from the house; 

 June 12th, another was found in the 

 edge of the woods still nearer the 

 house; June 6th, a Magnolia Warbler's 

 nest with three eggs was found a few 

 rods farther south in the edge of the 

 clearing; and on June 7th and 8th, I 

 found two more unfinished Chestnut- 

 sided Warbler's nests a short distance 

 away. In each of these a full set of 

 its owner's eggs were laid, but none 

 of the Cowbird. On June 12th, I found 

 a Red-eyed Vireo's nest with four 

 eggs, about five feet high in a small 

 maple sapling, between two small 

 branches and against the trunk of the 

 tree. On June 20th, three of these 

 eggs hatched. June 30th one of the 

 young Vireos left the nest, and I re- 

 moved the one addled egg. 



On the following morning, July 1st, 

 I found the old Vireos feeding their 

 young in the bushes near the nest, but 

 when I looked into the nest I was as- 

 tonished to see that, instead of being 

 empty, it contained a single, fresh 

 Cowbird's egg. This egg was almost 

 exactly like the one in the Chestnut- 

 sided Warbler's nest, and I am satis- 

 fied that it was laid by the same bird. 

 The nest may have been mistaken for 

 a newly completed one, but it certain- 

 ly did not look like one. Whatever 

 the intent of the bird that laid these 

 two eggs, it would be a bad thing for 

 the race of Molothrus ater if many of 

 her kind followed the example of this 

 particular misguided Cowbird. 



Now if any of you old timers have 

 ever seen or heard of anything of this 

 kind before, I wish you would write 

 of it to The Oologist, for it is some- 

 thing absolutely new to me. 



D. C. Mabbott. 

 Unity, Wis. 



