272 THE BIRDS OF THE BRITISH ISLES. 



that a bird may, unaided, cross the Atlantic is gradually gain- 

 ing ground as facts accumulate. This species nests in North 

 America and winters in South America, passing the West 

 Indies on migration. It has occurred at least a dozen times 

 in the southern and south western counties of England and 

 Wales, in Ireland and Scotland. It constructs a nest and 

 incubates its eggs. The call is described as a monotonous koo^ 

 koo, koo. The upper parts are greyish brown, rufous on the 

 wings, the under parts white. The upper mandible is black on 

 the cu'men, the rest of the bill is bright yellow ; the legs are 

 lead-grey. Length, ii ins. Wing, 5*9 ins. Tarsus, i in. 



Black-billed Cuckoo. Coccyzus erythrophthalmus 

 (Wilson). 



A single example of this North American Cuckoo was killed 

 in Antrim in 187 1 ; it has also occurred in Italy. It has a 

 metallic greenish-grey back, slate crown, and the under parts 

 are huffish white. The skin surrounding the eye is vermilion. 

 Length, 11 ins. Wing, 5'6 ins. Tarsus, -95 in. 



Order CORACIIFORMES. Picarian Birds. 



Sub-order CYPSELI. Swifts. 



The Swifts, superficially like the Swallows, have certain 

 characters similar to those of Passerine birds, but in most 

 points are closely allied to the Humming Birds and other 

 Picarian groups. The four toes are directed forward, unsuited 

 for perching but adapted for cHnging to rough surfaces. 



