122 BIRDS' NESTS 



with feathers, etc., which it places in the deserted 

 home of a Crow, Magpie, a Rook, or even in the old 

 drey of a squirrel. Again, some, but not all, of the 

 Nuthatches (Sittinae) more or less habitually resort 

 to holes in timber for nesting purposes, not, however, 

 boring these for themselves, but in most cases plaster- 

 ing up the entrance with mud, leaving a circular 

 entrance just large enough to admit the parent birds. 

 At the bottom of the selected hole a slight bed of dry 

 leaves and flakes of bark is arranged, and upon this 

 the eggs are deposited. The amount of plaster work 

 at the entrance varies considerably according to the 

 size of the hole. As many as eleven pounds of clay 

 have been found attached to one nesting site of the 

 Common Nuthatch {Sitta ccesia), in the side of a hay- 

 stack, this latter nest being still, I believe, in the 

 Natural History Museum at South Kensington. 

 Then some of the Flycatchers resort to holes in trees 

 for nesting purposes. One of the most familiar 

 species to British ornithologists is the Pied Flycatcher 

 (Muscicapa atricapilla), the nest of which is very 

 frequently built in a hole of a birch tree, often in the 

 deserted hole of a Woodpecker. The habit, however, 

 is not universal even in this single species, for the 

 bird on occasion finds a similar site in a hole in a 

 wall or a crevice of a rock. The nest is cup-shaped, 

 and made of dry grass, dead leaves, moss, wool, 

 hair and feathers, all more or less felted together. 

 Other allied birds nesting in a similar way are con- 



