Perhaps the word "build" is scarcely the right one, inasmuch as the nest is even more simple than that of the sand-martin.
The sand-martin, the house-martin's cousin, prefers the side of a cliff.
The sand-martin arrives much about the same time with the swallow, and lays, as she does, from four to six white eggs.
The sand-martin has several broods in the year, and is more regular than other Hirundinidae in its departure for the south.
The Indian sand-martin (Cotile sinensis) is, I believe, the smallest of the swallow tribe.
Another inhabitant of the banks is the sand-martin, which also likes company in the work of raising a family.
There must be something in the climatic conditions of South India that suits neither this nor the other species of sand-martin.