302 



OHIO EXPERIMENT STATION. 



The Cowbird seems here to most frequently invade the nest of the Rose-breasted 

 Grosbeak, and not uncommonly deposits two or three eggs in. a single nest. Next to 

 the Rose-breasted Grosbeak, the Yellow Warbler and Wood Thrush are probably 

 the species most frequently imposed upon by this parasite. 



On June 22, 1890, a nest of the Yellow Warbler was found to contain one young 

 Warbler and two eggs about to hatch, together with one Cowbird's egg which was 

 nearly fresh. A Song Sparrow's nest containing two young Sparrows, and a Cow- 

 bird's egg only one-eighth incubated, was observed June 5, 1892. From these 

 instances it would seem evident that the Cowbird sometimes makes mistakes in the 

 deposition of its eggs, placing them in nests where exists at most but small proba- 

 bility of their being hatched. On June 22, 1891, there was discovered a Yellow 

 Warbler's nest containing one young Warbler and a young Cowbird, both about 

 two-thirds fledged. The two quite filled the nest, the Cowbird by its much greater 

 -size being readily distinguished. Whether or not in this case the young Cowbird 

 eventually appropriated the entire nest, as is said to be a common occurrence, was 

 unfortunately not possible to determine. 



GENUS AGELAIUS VIEILLOT. 



101. Agelaius phceniceus (LINN.). 

 Red-wiuged Blackbird. 



An abundant summer resident. It appears in spring generally during the 

 first week of March, but was in 1892 noted on February 25. It departs rarely before 

 November i, sometimes remaining until November 30. 



From the time of its arrival it moves much in flocks, and is to be seen almost 

 everywhere, resorting, however, at night in great numbers to the swamps to roost. 

 This continues until the latter part of April, when the birds become more or less 

 -scattered for the purpose of breeding, which takes place chiefly in May and the first 

 part of June. 



During the nesting season the Red-winged Blackbird may be found in almost 

 every swamp and marsh, though apparently more than a few pairs seldom breed 

 together. The nest is very frequently placed in a bush or small tree, especially a 

 willow, and is sometimes ten or fifteen feet from the ground. The eggs appear to be 

 usually four in number. 



Six nests afford the following measurements : 



