304 BIRD WATCHING 



the moss and leaves that it deems necessary and made 

 therewith the mass and bulk of the nest, resorts to 

 some little ditch or sluggish stream and trowels up 

 from its margin mud indeed, but not mud alone, for 

 there is amidst it generally, if not always a certain 

 proportion of the fibrous roots or rootlets of mud- 

 loving aquatic plants. Of these, the bird can take a 

 firm hold with its bill, and as the mud adheres to the 

 fibrous network, it is enabled to carry a considerable 

 quantity of it at a time, though a greater or less 

 amount often falls off during the passage. It is in 

 this circumstance, as I believe, that one can read the 

 origin of the " extraordinary habit," as Darwin calls 

 it, of a bird's plastering the inside of its nest with 

 mud. It is the thrush to which he alludes, but the 

 description applies equally, and, in respect of the 

 material employed, still more accurately, to the black- 

 bird. At a certain point in its construction, the nest 

 of the latter would be mistaken by anyone without 

 previous experience, for that of a thrush, the cup being 

 as deep and perfect in form and the workmanship not 

 noticeably inferior. It is, however, of a darker colour 

 black, or approaching to black though this may 

 vary, according to locality. Over the whole surface 

 are seen the scorings of the bird's beak, which seems 

 to have been used as a trowel. But now, if the nest 

 had been examined a day or two before, its interior, 

 and, especially, the bottom of it, would have been found 

 to be composed of a dank moist mass of vegetation, 

 largely consisting of small water-plants, both the green 

 part and the roots, to the many fibres of which latter a 

 quantity of mud was adhering. Here, then, we read 

 the whole story. Fibrous material was needed on 



