ST.* KILDA AND ITS BIRDS. 879 



strong beats of the wing, and were soon lost to view out to 

 sea, or behind the cliffs. One of them in its flight 

 violently collided with a puffin and fell to the ground as 

 if dead, but after about a minute it recovered itself and 

 rose again on the wing. They were very silent. In 

 the case of four birds taken on the egg, dissection showed 

 them all to be males. These birds are said to arrive in 

 April and to leave in September. The plumage of the 

 young bird almost exactly resembles that of the adult. 



Pujjbnus anglorum (Manx Shearwater). 



This bird appears to be still plentiful, but less so than 

 formerly, owing, the natives say, to its having been driven 

 out by the increase of the Puffin. It breeds both on the 

 main island and all the subsidiary islands, but is most 

 abundant on Soay. Its burrows are generally deeper than 

 those of the Puffin, and it is difficult to get at. There is 

 an interesting colony of these birds on the main island, 

 where they nest under enormous boulders, which have at 

 some distant period been detached from the cliffs above, 

 and now strew the hillside in endless confusion. Some 

 of these boulders are of immense size, and there are 

 formed underneath them regular caverns large enough for 

 a man to crawl along; and it is in -burrows leading out of 

 the damp, gloomy recesses thus formed that the Shear- 

 waters lay. An egg which I obtained in this situation, 

 on June 18th, was very highly incubated — almost ready 

 for hatching, in fact. The sitting bird proved, on dissec- 

 tion, to be a male. Another bird, also a male, captured in 

 another burrow, but which was not on an egg, had the 

 proventriculus distended with a soft greenish pulpy sub- 

 stance, having much the appearance and consistence of 

 boiled spinach, only of a brighter green ; whereas the 

 stomach of the sitting bird was empty. The natives say 



