NOTES ON SOME OF THE BIRDS OF BUTE 27 



of entries. It has occurred to me that one might also take 

 the exact time occupied by the birds in making the passage, 

 as they can be watched for the whole distance with a 

 powerful telescope. One might thus collect accurate facts 

 as to the average speed of the flight of Rooks, and the 

 extent to which they are affected by adverse winds ; but this 

 still remains to be done. 



I cannot suggest any special reason for this regular 

 passage. Bute is well cultivated. Moreover, only some of 

 the Rooks cross. On days when I have seen numbers 

 crossing, I have noticed that there were still considerable 

 numbers scattered over the island. 



After fairly careful observation I came to the conclusion 

 that for some species of birds a sea-barrier of even a mile 

 is of very considerable importance, while for others it 

 apparently forms no practical barrier whatever. 



The Raven. I have to add the Raven to the breeding- 

 list of Bute birds, as, though it has long been known locally 

 to breed, the fact has apparently not yet been published. 

 The Raven is mentioned in the very curious and interesting 

 list of Bute birds published in Blain's History of Bute about 

 a hundred years ago, so apparently it has long been resident 

 on the island. At least two or three pairs have bred each 

 year ; in 1917 possibly five pairs. One nest is near Kilmichael, 

 at the north end, and one or two near the extreme south 

 end. This year, on 13th March, along with Dr J. N. 

 Marshall, I visited a nest near Kilchattan Bay. We found 

 the nest without any difficulty and had a good view of both 

 birds. They were not very wild, but never came within a 

 hundred yards of us, though they showed considerable 

 anxiety when we approached the nest. The birds appeared 

 to be hatching, though very shortly before this date there 

 had been seventeen degrees of frost, and a week or two later 

 there was a heavy fall of snow. These birds are protected 

 by Lord Bute's orders. 



The Magpie. For a number of years this bird was 

 apparently extinct on Bute, but in the last year or so it has 



