THE EAVES-SWALLOW. 205 



Usually mates do not go together. One stops by the nest and 

 rests or works upon it while the other flies after mud. They 

 stop and chat a moment together and then change places, the 

 loaded newcomer remaining to plaster and build up the home 

 while the other joins the outgoing mud-seekers. When the 

 nest is small, one bird starts out just as the other arrives ; 

 they say, " How do you do ? " in passing and waste no time ; 

 but when it is nearly finished, and time is not so important to 

 them, they sit in the nest and converse a little while. The 

 colony I am speaking of went about five hundred yards for its 

 mud, that is, rather more than.quarter of a mile, but no 

 doubt they sometimes go much farther. 



The bird with the load of mud, on arriving at the nest, 

 rests a moment, then begins retching violently and ejects a 

 large ball of mud, which it adds to the edge of the nest. This 

 is immediately followed by one or two smaller mouthfuls. 

 These are placed more carefully than the first and often seem 

 to be mixed in the bird's mouth before they are deposited. 

 Perhaps some sticky saliva is worked into them to make them 

 adhere more closely to the mass. There is need that the nest 

 should be made as firm as possible, for when the young are 

 well grown it must support a considerable weight. With us 

 the swallows use both the white clay and the blue sea clay. 

 The blue marine clay, containing seashells and sea plants and 

 still smelling of the briny ocean, underlies the white fresh-water 

 clay, which was' deposited later. In making bricks men have 

 used up the white clay and have worked down to the blue sea- 

 deposit. This is valueless for brick-making, but, oddly enough, 

 the swallows seem to find it just as good as the other, of which 

 they can get any amount and quite as near. 



One might watch some time and yet not see the swallow 

 lay the foundations of her house ; and, without seeing it done, 



