NON-INDIGENOUS BRITISH BIRDS. 137 



brown, and sparingly marked with richer brown. Rarer 

 types have most of the markings gray underlying ones, 

 or the brown surface markings distributed in net-like 

 and confluent streaks. Average measurement, 2'2 inches 

 in length by 17 inch in breadth. Incubation, performed 

 chiefly by the female, lasts about three weeks. If the 

 first clutch of eggs be taken others are generally laid. 



Diagnostic characters : The eggs of the Black 

 Kite cannot be distinguished from those of the Common 

 Buzzard, the Common Kite, and the Rough-legged 

 Buzzard. They require careful identification. The rag- 

 lined nest is characteristic of the two Kites only, but 

 in every case great care should be used in identifying 

 them. 



Family FALCONID.^. Genus Elaxoides. 



Sub-family BUTEONIN.^. 



SWALLOW -TAILED KITE. 



Elanoides furcatus i^LinncBus), 



(British : Very rare abnormal autumn migrant.) 



Single Brooded. Laying season, May. 



Breeding area : Southern Nearctic region and 

 extreme north of Neotropical region. The Swallow- 

 tailed Kite breeds from the mountains of Central 

 America northwards into the United States as far as 

 Southern Wisconsin, and east of the Rocky Mountains. 



Breeding habits : The Swallow-tailed Kite is a 

 regular migrant to the United States, reaching its 

 breeding areas early in April. It is a decidedly 

 gregarious bird whilst on passage, and so far as is 

 known apparently breeds in societies. Of its pairing 

 habits nothing definite has been observed beyond what 



