104 



Wild Birds. 



who as a class are extremely neat and clean. This is especially true of many 

 species who breed in holes or cavities of any kind like the Woodpeckers and Chick- 

 adees, the young of which are crowded in close quarters or even piled up in more than 

 one layer. The Woodpecker's hole and the Bluebird's nest are always sweet and clean, 

 and the nestlings immaculate. 



The duty of inspection and, if necessary, nest-cleaning follows each feeding with 



clock-like regularity, and is one of 

 the most characteristic and import- 

 ant activities to be observed in the 

 nesting habits of a large number of 



o o 



the smaller land birds, yet apparently 

 it is not mentioned in the standard 

 treatises of ornithology, and I have 

 found but few references to it in 

 works of any kind. Audubon, who 

 has probably recorded more facts on 

 the behavior of American birds than 

 any other writer, does not, I believe, 

 mention this important function. 

 The reason is not far to seek, for 

 without the possibility of close ap- 

 proach to the nest, and the use of a 

 convenient blind, such acts are 

 difficult or impossible to observe. 



The instinct of inspecting and 

 cleaning the nest is mainly confined 

 to the great passerine and picarian 

 orders represented in this country 

 by hundreds of species. It is a 

 well-marked trait in Thrushes, Wax- 

 wings, Vireos, Warblers, Orioles, 

 Blackbirds, and Woodpeckers, to 

 mention those families in which it 

 has been observed. 



The excreta of the young leave 

 the cloaca in the form of white, 

 opaque or transparent, mucous sacs. 

 The sac is probably secreted at the lower end of the alimentary canal, and is sufficiently 

 consistent to admit of being picked up without soiling bill or fingers. The parent birds 

 often leave the nest hurriedly bearing one of these small white packages in bill, an action 

 full of significance to every member of the family. I have seen the Oriole carry these 

 packages a few rods from the nest and drop them before alighting. The Bluebird and 

 Redwing Blackbird take them a long distance before letting them fall. 



Some Crow Blackbirds which I watched last spring had their young in the top of a 

 fir tree beside a small pond, which lay between me and their nest. In approaching with 



Fig. 100. Brown Thrush feeding a nestling. " The food is placed 

 not simply in the mouth of the young, but well down into the sensi- 

 tive throat." 



