1 68 NATURAL HISTORY OF SELBORNE. 



A few house-martins begin to appear about the 1 6th April; 

 usually some few days later than the swallow. For some time 

 after they appear the hirundines in general pay no attention to the 

 business of nidification, but play and sport about, either to recruit 

 from the fatigue of their journey, if they do migrate at all, or else 

 that their blood may recover its true tone and texture after it has 

 been so long benumbed by the severities of winter. About the 

 middle of May, if the weather be fine, the martin begins to think 

 in earnest of providing a mansion for its family. The crust or 

 shell of this nest seems to be formed of such dirt or loam as comes 

 most readily to hand, and is tempered and wrought together with 

 little bits of broken straws to render it tough and tenacious. As 

 this bird often builds against a perpendicular wall without any 

 projecting ledge under, it requires its utmost efforts to get the first 

 foundation firmly fixed, so that it may safely carry the superstruc- 

 ture. On this occasion the bird not only clings with its claws, 

 but partly supports itself by strongly inclining its tail against the 

 wall, making that a fulcrum ; and thus steadied, it works and 

 plasters the materials into the face of the brick or stone. But 

 then, that this work may not, while it is soft and green, pull itself 

 down by Its own weight, the provident architect has prudence and 

 forbearance enough not to advance her work too fast 5 but by 

 building only in the morning, and by dedicating the rest of the 

 day to food and amusement, gives it sufficient time to dry and 

 harden. About half an inch seems to be a sufficient layer for a 

 day. Thus careful workmen, when they build mud-walls (informed 

 at first perhaps by this little bird), raise but a moderate layer at a 

 time, and then desist, lest the work should become top-heavy, and 

 so be ruined by its own weight. By this method in about ten or 

 twelve days is formed a hemispheric nest with a small aperture 

 towards the top, strong, compact, and warm ; and perfectly fitted 

 for all the purposes for which it was intended. But then nothing 

 is more common than for the house-sparrow, as soon as the shell 

 is finished, to seize on it as its own, to eject the owner, and to 

 line it after its own manner. 



After so much labour is bestowed in erecting a mansion, as 

 Nature seldom works in vain, martins will breed on for several 



