222 Order XIV 



frogs, and leeches ; the nest of rotting weeds is always in 

 a marsh, and the eggs are usually dark coloured. 



The White-winged Black Tern (H. leucoptera) is a 

 blacker bird with red bill and feet, white tail, and white 

 wings that become grey from about the middle to the 

 tips ; it is a rarer visitor to Britain than the Black Tern, 

 but is seen at similar seasons and has similar habits. 

 From Poland and the Rhone valley it appears to extend 

 to north Africa, while it ranges from the Caspian Sea 

 to China, but further information seems necessary 

 before we can lay down certain limits. 



The Whiskered Tern (H. leucopareia) is quite irregular 

 in its visits to our shores ; it is as much a marsh Tern 

 as its congeners, but in colour is grey with a black head 

 and belly, red bill and feet and a white cheek-stripe. 

 The range is more southerly, comprising the south of 

 Spain, southern Russia, Turkey, Greece, and north 

 Africa, and extending thence to north India and 

 perhaps Mongolia. A few pairs breed in the south 

 of Germany, Poland, and at the mouth of the Rhone. 



This species is given here merely for purposes of 

 comparison, while the Gull-billed Tern and the large 

 Caspian Tern must certainly be left to the subsequent 

 list of uncommon migrants ; but we may note that both 

 have bred as near to Britain as the island of Sylt off 

 the shores of Denmark, and possibly may be found 

 more frequent visitors to our shores than has been 

 supposed. They belong to the following genus, Sterna, 

 and not to Hydrochelidon. 



The Sandwich Tern (Sterna sandvicensis), the largest 

 of the species which breed with us, does so regularly 

 on the Fame Islands off Northumberland, Raven- 

 glass in Cumberland, and thence northwards in certain 



