A most unusual family of skilled house-builders are the brush-tailed rat-kangaroos, or Jerboa kangaroos of Australia and Tasmania. They are no larger than an ordinary rabbit, but they have cousins who are as large as a man. These rat-kangaroos have most interesting tails, covered with long hair which forms itself into a crest near the tip. Their homes are found among small grassy hills, where there are a few trees and bushes. They scratch out a small hole in the ground, near a tuft of tall grass, and so bend the grass as to form a complete roof to the house, which is rather poorly constructed, and whose chief interest lies in the unusual way the kangaroos have of carrying all the building materials, like tiny bundles of hay, held compactly in their tails. There is no other workman among the animals that employs quite this method of transporting materials.
The rat-kangaroos have a dainty little brown cousin that lives in Africa, and who is occasionally seen jumping around on the ground, underneath bushes, and near damp springs. He is very small, not over three inches in length, and is like a miniature kangaroo, except for his long tail. Like their great cousins—the kangaroos—Mrs. Jerboa often carries her babies on her back when she goes out to seek food.
In the Great Sahara Desert, parched and dry, are found numerous cities of these little animals. With the exception of a few birds, reptiles, jackals and hyenas, they are the only inhabitants of this barren and desolate land. From the Arabs we learn that these little animals have extensive and intricate burrows, consisting of innumerable passages tunnelled out in the hard, dry soil. And these tunnels are the result of combined labour on the part of the entire community. The least alarm causes them to scuffle away into their underground homes.
One of the larger species of Central Asia employs a stratagem that is remarkable. Like their cousins of Africa, they live in a great underground city which is a perfect network of burrows which end in a large central chamber. From this chamber a long winding tunnel terminates very near the surface of the ground, and it is a long distance from the other burrows. No sign of its existence appears from above the surface of the earth, but if an enemy invades the burrow, away the jerboas rush for this secret exit and break through to the surface out of reach of the trouble, and escape.
These African jerboas are exceedingly odd in appearance, and they are two-legged in their habits of walk, and never go on all-fours. They walk by placing one hind foot alternately before the other; and they run in the same way. They can leap an extraordinary distance.
Frogs and toads, as a class, are not so skilled in house-building as some of their higher relations, but there is one of their number—the Hyla faber—that is remarkably gifted in building mud houses. He lives in Brazil, and the natives call him the ferreiro, or smith, and he is indeed the master-builder of his family. Mrs. Hyla is really the gifted member of the tribe, and it is during the breeding season that she diligently dives underneath the water, digs up handfuls of mud, and builds on the bottom a small circular wall, which encloses a space about ten to fourteen inches in diameter. This wall is continued until it reaches about four inches above the surface of the water. It looks not unlike a small volcano, and the inside is skilfully smoothed. This has been done by Mrs. Frog's artistic hands. When the house is entirely completed, Mrs. Frog lays a great number of eggs, and here they are quite safe from enemies both as eggs and baby tadpoles.
Mr. Frog seems little concerned in the building of the home, but he does take pleasure in croaking for Mrs. Frog while she works. Perhaps this is to her heart genuine music, and his faithful attention to their children makes up for his love of idleness!
Perhaps the strangest animal engineer in the world is found in Madagascar and Australia. It is the duckbill or duckmole, and is scientifically known as the Ornithorhynchus paradoxus. The natives of Australia call it by several names: Mallangong, Tambreet, and not a few call it, Tohunbuck.
This odd little aquatic engineer digs long tunnels of great intricacy in the bands of lazy rivers, and because of its paradoxical nature and appearance has caused many strange stories to originate about its habits and methods of propagation. It has the beak of a duck and waddles not unlike this bird, but, like other mammals, it gives birth to its young, and does not lay eggs, as is so often claimed for it. When swimming it looks like a bunch of floating weeds or grass.
Its home is always on the banks of a stream, and is always provided with two entrances: one below the surface of the water, and the other above. This insures escape in case of enemies. The main tunnel or road to the home is sometimes fifty feet in length, and no engineer could devise a more deceptive approach; it winds up and down like a huge serpent, to the right, and to the left, and is so annoyingly variable in its sinuous course that even the natives have great trouble in digging the duckbill out of its nest.