CONCEALED OR COVERED NESTS 101 



ever described, the birds, in some instances, having 

 literally to wade through water to reach the entrance 

 of the burrow concealed under the bank. Some of 

 the Whale-birds- and Prions are also accomplished 

 burrowers. Dr Kidder records the following respect- 

 ing the underground nest of one of the former, the 

 Halobcena ccerulea of ornithologists: "The burrows 

 are excavated beneath the mounds of an umbelliferous 

 plant, which abounds on the Kerguelen hillside 

 (Azorella selago), growing in dense masses of often 

 several feet in diameter. The holes usually run 

 straight inward for a foot or more, then turn sharply 

 to the right or left, parallel with the hillside, thence 

 downward, often doubling once or twice upon them- 

 selves and communicating with other entrances. At 

 the bottom is an enlarged cavity, lined with fine root- 

 fibres, twigs, ferns or leaves of the ' Kerguelen tea ' 

 (Accena affinis), and quite dry. Here the single egg 

 is to be found, always quite covered with dry powdered 

 earth or the leaves above mentioned. The diameter 

 of the burrows at their entrance is about that of a 

 man's wrist." Then, again, the Shearwaters (Puffinus) 

 are most expert burrowers, and form a slight nest at 

 the end of a tunnel. One of the most familiar species 

 is the Manx Shearwater (Puffinus anglorum), which 

 gathers in certain spots on the British Islands to rear 

 its young. All these birds are more or less gregarious, 

 and the ground of their chosen haunts is honeycombed 

 in all directions. 



