406 ZOO-GEOGRAPHICAL NOTES.

instance. It builds its sleeping nests of branches and leaves in the highest and strongest trees, and stays in them till late in the morning.

While it has been thus demonstrated that the boundary-lines of the vegetation coincide for the most part with those of the fauna, it is natural to expect that other facts relating to this subject will be found in our territory. It is known that birds of prey are rare in the proper forest region, and this has been proved to correspond with their distribution towards the south. Except in Uganda, where daily executions supply the necessaries of life to a considerable number of vultures, the regions to the south of 4° N. lat. are poor in birds of prey, unless they are steppe regions, In Monbuttu, where no cattle are kept, I only saw a single vulture, which, on the bank of the Kibali, was probably pondering over the competition of the population. The commonest bird of prey there is Asturinula monogrammica, Temm., which lives on Fringillide. Already in Makraka Milvus parasiticus, Forsk., is rare, though elsewhere it is one of the plagues of our country. Where the forest region begins, the carrion vultures, the eagles, Melierax, Poliornis, and others, almost entirely disappear, because their food is only found in open country.

Were the boundaries between steppe and forest, as well as between their connecting-links, everywhere sharply defined, we should be able to draw direct inferences from the vegetation of a country as to the nature of its fauna. But this is not the case; on the contrary, the various regions run so much into one another that a real separation is impossible, and hence it happens that in every locality which admits of it we find the inhabitants of two different regions intermingled. Thus Monbuttu, belonging to the western region, besides harbouring the purely western animals, supplies us with a number of animals that have long been known to us in the Kast African region. Thus, too, the inhabitants of the south and west push as far north and east as the conditions of climate and sustenance allow them, and the occurrence of such species comparatively far to the north seems to depend only on the possibility of their procuring suitable food, viz., on vegetation, climate, and elevation. But why certain species of animals inhabit a well-