138 BIRDS OF TIERRA DEL FUEGO 



Sterna cassinii, Ahiott, Ibis, p. 16G, 18G1. 



TTahitaf. — South America, on tlio east from Brazil, on the west from 

 Peru to Cape Horn ; the Falkland Islands ; South Georgia Islands ; South 

 Shetland Islands. 



(J, ? , Useless Bay, 5th Jan., 1905. 



Iris — black ; bill and legs — bright scarlet. 



The Swallow Tern is common on such parts of the coast as 

 are favourable to its existence. I have never remarked it inland. 

 It appears to prefer a rocky coast with here and there a spit of 

 shingle to an open flat shore. Much of its time it rests 

 on large rocks, surrounded by water. Its expanse of wing is so 

 enormous in proportion to its size as to appear to burden its 

 flight, entailing vastly unnecessary^ labour in moving the shortest 

 possible distance. It would be hard to find a more delicately 

 and beautifully coloured creature in its soft silver grey and 

 snow-white plumage, with long sharp needle -like scarlet biU 

 and tiny scarlet legs and feet. It is, however, anything but 

 pleasant in its attitude to man — it is ever noisy and aggressive 

 after the manner of its kind. 



I found a small breeding colony on a spit of shingle on the 

 southern shore of Useless Bay on January 10th. There were 

 about one hundred birds, and numbers of nests placed close 

 together in an area some fifty yards long by three or four yards 

 broad parallel with and only a few feet above high tide mark. 

 The usual number of eggs in each nest was two, laid in a 

 slight depression in the bare shingle. I took about a dozen, 

 representative of more than half a dozen distinct types. Unfor- 

 tunately, with the exception of three, all proved too far incubated 

 for preservation. No pair of eggs of all I saw exactly resembled 

 any other pair. Not only did they differ vastly in shape, but in 

 ground colour and markings. They were variously ovate, short 

 ovate, elongate ovate, or ovate pyriform. In ground colour they 

 ranged from pale greenish blue to ochre brown. The markings 



