GEOGRAPHICAL DISTRIBUTION OF ANIMALS
insular habitat. The absence of dangerous enemies, which prey upon the birds and upon their eggs and young, makes flight less essential to their existence. Very often, too, the prevalence of violent winds makes it advantageous for both birds and insects to remain on or near the ground, and not to attempt high or long flights, which involve the risk of being blown out to sea. Many birds do cross the sea for long distances when carried away by storms, but when land birds are so swept from the land they are likely to be destroyed. Most people who have taken a sea voyage have seen land birds, far out at sea, come aboard the ship, exhausted from their long flight, to rest in the rigging. Occasionally these waifs find new homes in remote lands, which have doubtless in this way received their bird inhabitants.
In the Galapagos there is a flightless cormorant, which lives by fishing in the sea. The penguins, those remarkable birds whose wings have been converted into swimming paddles or flippers, live on islands in the seas of the southern hemisphere, where they are safe from the attacks of enemies. The extinct dodo was a large, flightless pigeon, which lived on the island of Mauritius until it was exterminated by sailors and by introduced pigs. Another flightless pigeon, also extinct, was the solitaire of the Isle de Bourbon. New Zealand had many very large flightless birds, the moas, which were destroyed by the Maoris when they settled the islands; and the flightless, almost wingless, little kiwi (Apteryx) still lives in New Zealand. It is true that some flightless birds, such as the African ostrich and the South American rhea, live on the continents, but these are large and strong birds and very swift runners, and are therefore able to escape the large beasts of prey and to defend themselves against the smaller ones.
[ 99 ]
