May, if the weather be fine, the martin begins to 

 think in earnest of providing a mansion for its fam- 



House-martins. 



ily. 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 per- 

 pendicular wall without any projecting ledge under, 

 it requires its utmost efforts to get the first founda- 

 tion firmly fixed, so that it may safely carry the su- 

 perstructure. On this occasion the bird not only 



195 



