PDF - Wallace Online

342 TROPICAL NATUREIt is true that brilliant tropical birds mostly belong togroups which are wholly tropical as the chatterers, toucans,trogons, and pittas ;but as there are perhaps an equal numberof tropical groups which are wholly dull-coloured, whileothers contain dull and bright-coloured species in nearly equalproportions, the evidence is by no means strong that tropicallight and heat have anything to do with the matter. Butthere are other groups in which the cold and temperate zonesproduce finer -coloured species than the tropics. Thus thearctic ducks and divers are handsomer than those of thetropical zone while the; king-duck of temperate America andthe mandarin-duck of North China are the most beautifullycoloured of the whole family. In the pheasant family wehave the gorgeous gold and silver pheasants in North Chinaand Mongolia, and the superb Impeyan pheasant in the temperateNorth-Western Himalayas, as against the peacock andfire -backed pheasants of tropical Asia. Then we have thecurious fact that most of the bright -coloured birds of thetropics are denizens of the forests, where they are shadedfrom the direct light of the sun, and that they abound nearthe equator, where cloudy skies are very prevalent ; while, onthe other hand, places where light and heat are at a maximumhave often dull -coloured birds. Such are the Saharaand other deserts, where almost all the living things aresand-coloured ;but the most curious case is that of the Galapagosislands, situated under the equator, and not far fromSouth America, where the most gorgeous colours abound, butwhich are yet characterised by prevailing dull and sombretints in birds, insects, and flowers, so that they reminded Mr.Darwin of the cold and barren plains of Patagonia ratherthan of any tropical country. Insects are wonderfullybrilliant in tropical countries generally, and any one lookingover a collection of South American or Malayan butterflieswould scout the idea of their being no more gaily -colouredthan the average of European species, and in this he wouldbe undoubtedly right. But on examination we should findthat all the more brilliantly-coloured groups were exclusivelytropical, and that where a genus has a wide range there islittle difference in coloration between the species of cold andwarm countries. Thus the European Vanessides, including