ST. KILDA. AND ITS BIRDS. 365 



winter. The largest concentration of these birds relative 

 to area is on Stack Lii, the entire top of which is perfectly 

 white with them, as well as the encircling ledges ; but 

 Stack an Armin is not greatly inferior to its neighbour in 

 this respect, although the birds are definitely less 

 numerous there. On the cliffs of Borer ay there are as 

 many birds as on the Stacks, but these being spread over 

 so much greater an area, the effect is not so striking. A 

 few birds are seen about the Stacks where they breed early 

 in March, and by the end of that month the rocks are 

 fully tenanted. In April they set about making and 

 repairing their nests. They begin to lay sparingly in 

 favourable seasons at the end of April, but the eggs are 

 not obtained in any numbers before the first or second 

 week in May. Fully a fortnight will elapse from the 

 time of the first birds laying before eggs are found in all 

 the nests. On the occasion of my visit, on June 10th, the 

 sloping faces on the top of Stack Lii were crammed with 

 nests as thick as they could be placed, every available spot 

 between the projecting angles and slabs of rock being thus 

 occupied. Almost every nest contained a single egg, the 

 great majority of which was stained a deep brown colour, 

 and these were all, so far as they were tested, considerably 

 incubated, the embryo being formed, but not of large size. 

 There was, however, a fair sprinkling of perfectly fresh, 

 clean eggs. I saw four nests containing two eggs each ; in 

 one of these both eggs were much stained and badly incu- 

 bated ; but in the other three, whilst one egg was in this 

 condition, the other was perfectly fresh and clean, so that a 

 considerable interval must have elapsed between the lay- 

 ings, which were in all probability performed by different 

 birds. As the top of this Stack had been cleared of eggs by 

 the natives on May 14th, the great majority of the eggs in 

 the nests must have been second layings. The eggs are 



