CONCEALED OR COVERED NESTS 107 



the British Swallow {H. rustica). There can be little 

 doubt that before buildings were available these birds 

 bred much more commonly in caves and crevices of 

 cliffs than they do at the present time. 



From nests made in caves we will pass to a con- 

 sideration of those that are habitually concealed under 

 stones or in crevices, holes and fissures of rocks. The 

 birds that resort to these situations are not only 

 numerous, but representatives of remotely allied 

 groups. Some of the Petrels, for instance, habitually 

 resort to stones and broken cliffs for breeding pur- 

 poses, whilst some others that generally nest in 

 burrows in the ground occasionally do so. Confining 

 our remarks to the most typical rock and stone 

 builders, we may illustrate these in the first instance 

 by the home of Wilson's Petrel {Oceanites oceanicus). 

 Of the nest of this Petrel on Kerguelen Island, Mr 

 R. Hall writes {Ibis, 1900, p. 20) as follows: "Go 

 straight to a wild-looking piece of the coast if you 

 want nests. Look under large or small slabs of 

 stone, or within the crevices of the cliff-sides. Most 

 of the nests are saucer-like, and neatly put together 

 with loose twigs. Your shovel will act as a lever to 

 lift the slabs and expose them, when the sitting bird 

 moves away to the farthest corner to escape the light, 

 never offering to bite, although the act would be harm- 

 less." Mr Hall goes on to say that the nests were 

 built principally of Azarella stalks, that they were flat 

 in shape, and placed in shallow indentations beneath 



