It was very interesting to see them holding to the trees, sometimes with their heads upward and sometimes with their heads downward. Some had just begun to work at the aperture, others had already made a pretty deep hole, and the end of their tail only could be seen, while still others were working inside, and their bodies could not be seen at all, though now and then they came forth, bringing the wood they had pecked out. [Illustration: THE BARBATULA WORKING.] What difficult and patient toil! The making of one of these nests requires many days. It is no easy work for birds a little bigger than a sparrow to peck out a circular opening of two inches in diameter, and more than two inches deep. This done, they dig perpendicularly down for about four inches. The cavity thus made is their nest. As they are small birds, it takes them a long time to finish this piece of carpentering—often two or three weeks. There the female lays her eggs and hatches them in security, no snake or wild animal being able to disturb them. Not only do they use these nests while they are hatching, but also during the rainy season. How cosy they must feel in these places of refuge when a storm is raging! Nothing could be safer, or better shelter them from the rain. The aperture being about two inches in thickness before you come to the perpendicular hollow, of course the rain can not reach the inside. I have seen trees entirely perforated by them; that is to say, having more than a dozen of these holes in them; and thus forming what we may call a little village of themselves. I wonder if they had a king! These birds are very shy, and the least noise will frighten them. How affectionate the pair seemed to be, how willing they were to help each other in their work! There is also another species of _Barbatula_ which I have discovered, of a gray color, called now _Barbatula fuliginosa_, of the same habits, but found in greater numbers. I have seen colonies of them, composed of thirty or forty nests, on the same tree. The picture given by the artist represents the birds working and making their nests. [Sidenote: _THE SYCOBIUS NIGERRIMUS._] Now I must speak to you of another bird, a very curious one, the _Sycobius nigerrimus_, which is found in almost if not all the regions I have explored in Equatorial Africa. The habits of this bird are most extraordinary. They are extremely sociable birds; the woods or the uninhabited plantations have no charm for them; they must be where people live, and hence they prefer always to live in the neighborhood of a village. If there are trees in the middle of the village they will live there, or on the trees back of the huts, and not far from where the palm or plantain-trees abound; but man must be in sight, for they seem to love his society. [Illustration: AFRICAN HANGING BIRDS’ NESTS.]