Jan., igog. Birds of Illinois and Wisconsin — Cory. 



505 



Yellow-billed Cuckoo. 



ground. The eggs are 3 to 5, pale greenish blue or bluish white, and 

 measure about 1.20 x. 90 inches. Mr. H. S. Swarth found it breeding 

 at Joliet, Illinois, June i, 1906. 



The notes of the Cuckoo are pleasing, but rather monotonous and 

 not particularly musical. They vary somewhat but the most charac- 

 teristic is the familiar cii-cu, cu-cu, repeated several times, from 

 which it has derived its name. 



186. Coccyzus erythropthalmus (Wils.). 

 Black-billed Cuckoo. 



Distr.: Eastern North America, from Rocky Mountains to the 

 coast; breeds in eastern United States and north to Labrador; south 

 in winter to West Indies and northern South America. 



Adult: Bill, brownish black (occasionally with a tinge of yellow 

 at base of lower mandible) ; upper plumage, grayish brown, with a 

 faint gloss of green; under parts, dull white; tail feathers, color of 

 back, tipped with white; primaries, pale olive brown, shading into 

 whitish at bases of inner w^ebs; eyelids, red. 



Length, 11 to 12; wing, about 5.25; tail, 6.25; bill, .75. 



Easily distinguished from the Yellow-billed Cuckoo by the black 

 lower mandible, absence of rufous on primaries, and the color of the 

 tail. 



The Black-billed Cuckoo is a common summer resident in Illinois 

 and Wisconsin. Arrives from the south in May and remains until 

 October. Kumlien and Hollister consider it more common than the 



