24 GEOGRAPHICAL DISTRIBUTION 



Four species are only known to breed in a subarctic climate : — 



Alca impennis (extinct) . 

 Stercorarius catarrhactes. 

 Procellaria pelayica. 

 Sula bassana. 



The breedini>:-range of three species extends both to subarctic and sub- 

 tropical climates : — 



Sterna hirundo. 

 Sterna nigra. 

 Puffinus anglorum. 



The breeding-range of two other species is also subarctic and subtropical^ 

 but it extends beyond into the tropics : — 



Sterna anglica. 

 Sterna cantiaca. 



Nearctic Species. 

 There are no fewer than 32 species of birds which are regarded as 

 accidental visitors to our Islands whose breeding-range is confined to the 

 American continent and the islands near it. Of these, fifteen are exclu- 

 sively arctic in their breeding-range : — 



Fringilla linaria hornemanni, 

 Falco yyrfalco candicans, 

 Falco yyrfalco islandus, 

 Surnia funerea hudsonia, 

 Charadrius fulvus americanus, 

 Numenius borealis, 

 Tr'inga honapartii^ 

 Tringa riifescens, 

 Tringa pectoralis, 

 Tringa minutilla, 

 Totanus flavipes, 

 Macrorliamplius griseus, 

 Larus leucopterus, 

 Fidigula albeola, 

 Fuligula histrionica ; 



five are both arctic and subarctic in their breeding-range : — 



Loxia leucoptera, 

 Accipiter atricapillus, 

 Mergus cucullatus, 

 Anas carolinensis, 

 Fuligula perspicillata ; 



