NOTES ON THE TREE-SPARROW IN DONEGAL. 301 



nest several times since they left. A stone has to be removed, 

 too, from the entrance to the nest before it can be examined. 

 There has been a very short interval since the first brood was . 

 reared. The young were in the nest, though ready to leave, on 

 June 14th. 



26th. — The Tree-.Sparrows are still adding material to the 

 nest in the wall of the field, though two eggs have been laid. 

 28th. — Four eggs in Tree-Sparrow's nest to-day. 

 On June 28th I had to leave this place. 

 In his paper in ' British Birds,' Professor Patten raised the 

 question again as to whether this colony could have existed 

 before I found it in 1907. I had stayed in the house, beside 

 which the colony was, during a considerable part of the nest 

 seasons of the two preceding years, and had naturally been 

 frequently in the garden, so I can hardly believe in the 

 possibility of the Tree-Sparrows having been there then. I 

 know how easy it is to overlook birds that one does not expect 

 to find, and in 1907 I had certainly been beside the colony for a 

 week or two before I discovered it ; but on the other hand I 

 recognized the birds the first time that I happened to go to the 

 garden ; and even before I saw them there I had already found 

 another nest (2) about one hundred yards away, which eventually 

 turned out to be a Tree- Sparrow's, and was keeping it under 

 observation. During practically the whole of this week I had 

 been working at some other birds some miles away, and had 

 taken it for granted that there was nothing to be found in the 

 garden in which I had often been in other years. 



Also there had been a large colony of House- Sparrows in the 

 garden, which has much diminished in numbers since I first 

 found the Tree-Sparrows. 



But the most interesting evidence for the colony having been 

 newly founded lies, in my opinion, in the fact to which I have 

 referred, of the two males breeding with one female. In the 

 'Irish Naturalist' for June, 1903, Mr. C. B. Moffat brought 

 forward a number of facts that suggest that the struggle for 

 existence and reproduction amongst birds takes the form rather 

 of a struggle for breeding ground than for the possession of 

 females. His argument was that the female was easily 

 obtainable by a male which had established its claims to a 



