There is another species of Furnarius, which the Spaniards call the
casarita, or little house-builder. This species builds its nest at the
bottom of a narrow cylindrical hole, which extends horizontally to
nearly six feet under ground. It generally chooses the side of a low
bank, but sometimes penetrates the mud walls round the houses, through
which it works its way, frequently--very much to its disappointment--
coming out unexpectedly on the opposite side.