A few words must be said about other land animals apart from mammals. In regard to birds it is noticeable that the habit of migration, and the fact that the greater part of the continent of Europe lies on the direct line between the northern breeding grounds of many species and the southern winter quarters, gives Europe a very rich bird fauna. The British Islands owe to their peculiarly mild climate a rich bird fauna at all seasons, for while the summer climate attracts many forms for nesting purposes, the mild winter brings many migrants flying from the cold of continental Europe.
In regard to birds as well as to other animals, the Mediterranean owes to its warm climate a richer fauna than countries farther north. Some interesting southern forms, such as pelican, flamingo and ibis, reach this region, though not extending into central Europe, except as stragglers.
The climate of Europe is not hot enough anywhere to lead to the presence of a rich reptilian fauna, but there is, again, a marked increase to the south. It is stated that there are only twenty-one species of reptiles in central Europe, while there are fifty-nine in southern Europe, and no less than a hundred and forty in the Mediterranean region taken in the large sense. Poisonous forms are few, and do not, as in hotter countries, constitute a serious menace to man. Very interesting is the presence of the chameleon in southern Spain, as in north Africa.
Perhaps the most important human aspect of the European reptiles is the presence of numbers of insect-eating forms. In the warmer parts of Europe every wall or patch of rock seems alive with lizards in the summer sunshine, and these must play a not inconsiderable part in the keeping down of noxious insects.
Omitting a great number of other groups, we may say something about insects, which are of enormous importance in human life, both directly and indirectly.
It has been shown of late years that many insects are the sole means by which certain very deadly diseases are transmitted from man to man, or from one animal to another. Almost every few months a new announcement of an insect-carried disease is made, but the most important forms are the following:—Mosquitoes and gnats transmit such diseases as malaria, yellow fever, and more horrible diseases still, due to the presence in the blood of small parasitic worms. Tsetse flies carry sleeping sickness, and also transmit the very fatal fly disease of domesticated animals, a fact which has been and is of great importance in the settlement of Africa. In the case of most diseases there seems to be a close connection between one particular species of insect and a particular disease.
Mosquitoes and gnats are very abundant in many parts of Europe, and the forms belonging to the genus Anopheles, which carry the germ of malaria, are widely distributed. In parts of the Mediterranean area their presence is associated with the prevalence of malaria, which has existed there for a prolonged period, and is believed by some to have had an important bearing upon the fates of the ancient civilisations of the Mediterranean basin.
The regions in Europe affected, or seriously affected, by malaria are diminishing yearly. This is now due to conscious efforts, but a similar process has been going on probably for a long period, for many obscure diseases, notably “ague,” seem to have been forms of malaria. Their disappearance seems to be due to drainage, which diminishes the breeding places of the mosquitoes, and also to the progress of agriculture, for ponds which form on rich, well-manured land are apparently unsuited to mosquito larvæ. The subject is of great geographical importance, for the spread of man over the surface of the globe, and the progress of civilisation must have been influenced in all time by the prevalence of fly-borne disease. Such diseases have hitherto been the greatest obstacle in the way of the civilisation of Africa.
In Uganda extensive tracts of fertile wooded land have had to be abandoned on account of the presence there of the tsetse fly, while, prior to this abandonment, there were districts in which every living soul had been destroyed by the deadly sleeping sickness transmitted by this fly. We can hardly suppose that such facts are without a parallel in human history; and man’s distribution over the surface of the globe, and in detail the distribution of his settlements within a country, have doubtless been greatly influenced by the distribution even of such insignificant creatures as the various kinds of flies.
Even apart from their power of transmitting disease, the blood-sucking flies must have influenced man in his choice of localities for settlements, and must have been an important factor in the process of adjustment to his surroundings. The naturalist Brehm gives an appalling picture of the number and blood-thirstiness of the mosquitoes of the Siberian tundra, which render life almost intolerable there for both man and beast in summer. Even within the British Islands the uncultivated and undrained regions are often badly infested with small blood-sucking flies, and their numbers must have been vastly greater in the old days before drainage and intensive cultivation had reduced them. It is quite possible that some of the anomalies in regard to the spread of particular races of men over the surface can be explained by the varying susceptibility of different races to insect attack, and there can be no doubt that the blood-sucking insects must have had some effect in determining the rapidity or slowness with which particular tracts were colonised by man.