350 THE ZOOLOGIST. 



I have seen Whinchats in this county on two or three occasions 

 in the nesting season, but they are not common, and I have 

 never found the nest. 



To the list for Co. Leitrim I have to add the Eock-Pipit. It 

 breeds commonly, as might be expected, along the three miles of 

 the Leitrim coast-line. 



For Co. Sligo I have to record the Great Black-backed 

 Gull and the Black Guillemot. I found a nest of the Great 

 Black-backed Gull with two eggs on the mainland of this county 

 on May 30th, 1906. Since then I have seen these birds in the 

 same spot in other seasons, but have never seen another nest. 

 Does this bird not breed regularly in Co. Sligo ? It may be an 

 accidental omission, but it is not given in ' The Birds of Ireland ' 

 as breeding there. 



Two or three pairs of Black Guillemots nest in one very 

 quiet locality in the east of Co. Sligo, and have done so, I have 

 been told, for many years. They never increase in number. 

 Eight years ago there were three pairs, and when I went back 

 there last year I found just the same number. I have been told 

 that Choughs bred in this spot many years ago. 



Last year I spent some time at a large colony of Arctic and 

 Common Terns in Co. Sligo. I was surprised to find that out 

 of perhaps five hundred Arctic Terns' nests not one had more 

 than two eggs. There was a much smaller colony of Common 

 Terns breeding on one part of the ground occupied by the Arctic 

 Terns, and the nests of most of the former had three eggs. I 

 spent some hours with a glass, identifying the birds as they 

 settled on their nests, but could not find a single Arctic Tern 

 with three eggs; and on the parts of the shore occupied by the 

 Arctic Terns alone there were certainly no nests with more than 

 two, though the clutches had been completed for some days. I 

 had been at that colony some years before, and a note in my 

 diary says that " very few " Arctic Terns had three eggs then. 

 I cannot even make a guess at the proportion that year, but I 

 fancy that several of the nests had three eggs. Last year the 

 Little Terns, too, in this colony had fewer nests than usual with 

 three eggs. 



The breeding status of certain of the Ducks is one of the most 

 puzzling questions in Irish ornithology. Mr. Ussher's list 



