THE CAVE MUDWALLER. 
457 
horizontally for some six or seven feet. The natives told Darwin that 
children had frequently attempted to unearth this nest, but had 
never succeeded. For the locality of his abode the bird chooses a 
small sloping bank of sandy but solid soil, on the margin of a roadway 
or a stream. In Bahia, says Darwin, the walls are built of earth ; and 
he remarked that those enclosing the courtyard of the house where he 
was residing were pierced in several places with circular holes. When 
he questioned his host on the subject, he was informed that they were 
the work of the accursed mudwallers ; and afterwards Darwin saw the 
birds engaged in making them. It is a curious fact that they seem 
to have no idea of thickness ; otherwise, they would surely not 
attempt to excavate their burrows in walls of clay, the dimensions of 
which, as they are constantly flying round them, they can hardly fail 
to know. Mr. Darwin states his belief that when, after having 
worked through the slender wall, the bird bursts suddenly into the 
light of day, he is completely stupified, and utterly at a loss to account 
for so extraordinary a circumstance. 
A similar account is given by Dr. Gray, who adds that the cave 
mudwaller is a bird of very gentle disposition, living peaceably and 
alone, and from morn to eve continually in motion. If scared or 
disturbed he flies some distance off", and there remains so immovable 
as to expose himself to death beneath the wheels of a passing vehicle, 
without making any further attempt at flight. 
THE HOOPOE. 
The last of the bird-builders to whom our space permits us to call 
the reader's attention, is the hoopoe, a bird of splendid plumage, dis- 
tinguished by the huppe or plumed tuft which adorns his head. The 
common hoopoe, or JJpupa epops, has a sufficiently wide range, being 
found in most parts of Europe, in the north of Africa, and in Central 
Asia as far as Kashmir. In the more temperate climes he seems to 
prefer the lightly-wooded plains for his habitat ; or he has no objection 
to the cultivated fields and pastures, if they are besprinkled with a 
few veneral)le trees. In Africa he is met with in every village, and 
even in the heart of the larger towns, where, like the stork and the 
