144 ANNALS OF SCOTTISH NATURAL HISTORY 



September. There are two species of them, the larger having 

 its tail forked like that of the swallow [LEACH'S FORK- 

 TAILED PETREL (Oceanodroma leucorrJwd)\. Otherwise they 

 are similar in appearance and habits. The smaller variety is 

 more numerous, and frequents all the islands of the group, 

 while the other frequents only Boreray and the northern part 

 of St. Kilda proper. 



The GANNET {Sula bassand\ is here called " suileire," the 

 sharp-eyed. A few birds will sometimes come as early as 

 the 1 3th of January, and from that time more and more 

 gradually arrive. By the end of February only about a 

 third of the birds will have come, and it is not till the end 

 of March that they are caught in any numbers, and then 

 only if the weather is suitable. When they arrive they are 

 fat and very good eating. Indeed, all the birds which visit 

 us are only good eating when they are fat, and as a rule the 

 fatter they are the more palatable. Gradually, as the breed- 

 ing season goes on, they get leaner, till by the time they 

 leave us in October and November they are very lean indeed. 

 They begin to lay about the loth of May, and it is very 

 probable that they all return to their old nests. The nest 

 is made of grass and small sticks, which are renewed from 

 time to time as hatching goes on. These materials decay- 

 ing annually form a small mound which gets yearly larger. 

 It lays one egg, which the parents hatch by turns for 

 about six weeks, and then feed the chick for at least 

 as long. When the young bird is first hatched it is quite 

 naked, but soon a fine down begins to grow, which gradually 

 gets very long. When it is about a month old it is called 

 "guga," and looks like a young white lamb. If the first 

 egg is taken away it will lay a second, and if it is again 

 robbed it will lay a third time. All of them will not lay 

 again. You may get on a ledge the first time say twenty 

 e gg s > the second time fifteen, and the third time about 

 twelve ; of course more than that number may lay again 

 and select some other place for the new nest, but I do not 

 think this at all probable. The same rule of numbers 

 applies to all those birds which lay one egg, and if robbed 

 lay again at all. After the young are hatched the parents 

 from time to time line the nest with fresh grass. For this 



