50 Proceedings of the Royal Physical Society. 



Mr Bonar thinks that the Peregrine's eyrie on Priest Island 

 has within the last two years been removed farther west along 

 the cliff. The cause of this change is doubtless the great 

 increase in the number of the Cormorants which nest on its 

 eastern part. 



12. Phalaceocorax carbo (Linn.). 



(Common Cormorant.) 



Very abundant, nesting in huge numbers on Priest Island. 

 There are also fairly large colonies on Eilean Dubh and Tanera 

 Beg, while a few pairs breed on Glasleac Mor. Mr Harvie- 

 Brown in 1884 estimated the number of pairs which nested 

 on Priest Island at one hundred and thirty. The colony has 

 at least doubled its numbers since his visit ; and I should 

 say that not less than three hundred pairs frequented the 

 island for nesting purposes last summer. According to 

 Mr Bonar's computation, the two colonies on Tanera Beg 

 contain at least fifty nests each. On Priest Island the 

 Cormorants nest on an inland cliff and not on precipices by 

 the sea, the reverse being the case with the Shag. On the 

 other islands visited by us on which both birds nest, we 

 found that the Cormorants bred near the top, and the Shags 

 near the bottom of the cliff. 



13. Phalaceocorax geaculus (Linn.). 



(Shag.) 



Abundant. Nests in large numbers on Priest Island, 

 Tanera Beg, Eilean Dubh, Glasleac Mor, and Bottle Island, 

 and also in smaller numbers on the adjoining mainland. 

 This bird breeds only on precipices by the sea, and I never 

 saw one nest which could be reached without very consider- 

 able risk. Very few eggs were observed until the last week 

 of June. On the 18th of that month Mr Bonar found a 

 great many incomplete nests, while on the 25th not a single 

 young bird had been hatched in either of two large colonies 

 which he visited. 



