124 BIRDS' NESTS 



species of Ducks (Anatidae) that resort more or less 

 regularly to holes in timber for breeding purposes. 

 Some of the most characteristic of these are the 

 Mandarin and Wood Ducks (Aix) of China and North 

 America respectively ; the Golden - eyes (Clangula), 

 Buffel-headed Duck (Ckaritonetta), Hooded Mergan- 

 sers (Lophodyfes), Goosanders (Merganser), and the 

 Smews (Mergus), all inhabitants of the Palaearctic and 

 Nearctic regions. None of these birds makes the 

 nest-hole for itself, and the eggs are deposited upon 

 the debris at the bottom, until they eventually 

 become surrounded by the characteristic coverlet of 

 down plucked from the parent's body during the 

 course of incubation. 



Then, again, we have to consider another very 

 extensive and heterogeneous group, in which the birds 

 conceal their nests more or less effectually in holes, 

 in or under banks or beneath tufts of vegetation. 

 Some of these nests, strictly speaking, come within 

 that division containing " Domed Nests," and 

 must, therefore, be reserved for a future chapter ; 

 but, on the other hand, a very considerable 

 number of them are open cup-shaped structures, 

 yet so cunningly and completely concealed that 

 the eggs and brooding bird are hidden from 

 all ordinary observation. By far the greatest number 

 of nests concealed in this manner are built by various 

 Passerine birds ; and as the number of species nesting 

 in this manner is so large, it would be practically im- 



