CONCEALED OR COVERED NESTS 109 



Some of the Parrots also nest in rock crevices, whilst 

 some of the Geese make their nests in hollows in 

 sandy clifiFs, as, for instance, the Chloephaga melan- 

 optera of Chili {conf. Ibis, 1897, p. 190). 



Amongst Passerine birds we have many instances 

 of nest-builders amongst rocks and stones. Such 

 sites are in some cases peculiar to entire groups; 

 in others they form exceptions to a very different 

 method of nidiflcation. Amongst the most thorough 

 rock-builders we may first mention the Chats 

 (Turdidse), of which our own Wheatear (Saxicola 

 cenanthe) is a very familiar example. Between thirty 

 and forty species of these birds are known to science. 

 Their nests are remarkably uniform, not only in the 

 manner of construction, but in their situation. The 

 Chats are pre-eminently rock birds; they are birds 

 of the bare, stony hillsides and boulder-strewn plains 

 and desert sands, showing no partiality for arboreal 

 haunts. Many of the species build their nests under 

 masses of broken rock, or in heaps of stones, others 

 select holes in the ground, often the deserted burrows 

 of some small animal, or in holes in ant-hills, as in 

 the case of Saxicola pileata. Their nests are cup- 

 shaped, somewhat loosely put together, and made 

 externally of dry grass, moss and roots, and lined 

 with finer roots and grass, sometimes hair and 

 feathers, but in some species both the latter soft 

 materials are omitted, as, for instance, in the Desert 

 Wheatear (S. deserti). Some of these nests are placed 



