In Chapter 12 of Swiss Family Robinson, the boys see something they think are men on horseback, perhaps Arabs. What do the "Arabs" prove to be?

In Chapter 12 of Swiss Family Robinson, the family is crossing plains that have become desertlike in the dry season. The family sees what appears to be a group of people on horseback galloping towards them, and they pass a spyglass (a kind of telescope) among themselves to see the distant objects more clearly. When the father, William, looks through the spyglass, he sees that the objects are actually large ostriches. There are five ostriches--4 "ashen brown" females and one male, whose white plumes contrast with his glossy black neck and body. An eagle swoops down on the male ostrich and kills it, and then the dogs devour it. The boys discover a nest filled with ostrich eggs, and as each egg weighs three pounds, the eggs are quite difficult to carry. However, the father ties the eggs to a stick so that they can be carried more easily.