91 



periplwna vesperlina, PlectropJiaws pictus, Ammodromus lecontei, Zono- 

 trichia vav. intermedia, Z. coronata, Z. qnerulea, Spizella pallida 

 (breeds), Eremophila var. leucolcema (breeds), Slimiella var. verjlccta 

 (breeds), Scolecopliagus cyanocephalns, Pica var. hudsonica, Chordiles 

 var. henriji (breeds), Biileo var. cahtrus (breeds?), B. swaiiisoni 

 (breeds?), Trinrja hairdii, Steganupus wilsoni (breeds), and numerous 

 others less strictly western. 



A belt about twenty-five miles wide, bordering Lake Miclui,'an in 

 Illinois, will include the field of tlie present paper. A few species 

 taken durinjr the migrations at Kacine, Wisconsin, have been ailded. 

 Although this locality is not situated within the precise limits of the 

 region to which this paper is limited, it being, however, but a few 

 miles north of the Illinois state line, upon tlie Lake shore and in the 

 direct line of migration, it would seem extremely improbable that a 

 northward bound species taken at Racine should not have passed 

 through the adjacent portion of Illinois. 



Not only is tlie influence of the Lake upon the fauna shown by the 

 occurrence of numerous species of birds, attracted by the presence of 

 a large body of water with its congenial surroundings, but the influ- 

 ence of the Lake upon tlie climate and the vegetation in its immediate 

 vicinity, has a marked influence upon tiie list of summer residents. 



As is well known, the country bordering upon tlie Great Lakes pos- 

 sesses an average lower temperature during summer, and a higher 

 temperature during the winter, than the surrounding districts. This 

 has a decided eflfect upon the movements and distribution of the birds 

 in the vicinity of these large bodies of water. 



This influence is seen in a retardation, often of a week or more, in 

 the spring migration, and in the scarcity of small woodland species 

 during the breeding season. Although birds are exceedingly luimer- 

 ous here during tlie migrations, and the number of species found dur- 

 ing tlie summer compares favorably with the number found at the 

 same season in other localities having the same latitude, they are 

 represented by decidedly few individuals. This fact is especially 

 noticeable after one has passed a day in the marshes of the vicinity, 

 where the abundance of numerous marsh and water birds, both in 

 species and individuals, would lead one to suppose the woods were 

 equally favored. 



The limits of the field discussed in this paper embrace two counties, 

 Cook County upon the south, and Lake County upon the north. Each 

 possesses certain topographical peculiarities. Cook County is mainly 

 prairie land, interspersed with ridges and groves of timber, the for- 

 mer of which generally extend parallel to the Lake shore. Near the 

 south-eastern portion of the county the surface of the prairie is but 

 slightly above the level of the lake. Through this county flows the 



