PDF - Wallace Online

HUMMING-BIRDSof being excessively long and pointed; their plumage isarranged differently; and their feet are long and strong,instead of being excessively short and weak. There remainonly the superficial characters of small size and brilliantmetallic colours to assimilate them with the humming-birds,and one structural feature a tubular and somewhat extensiletongue. This, however, is a strictly adaptive character, thesun-birds feeding on small insects and the nectar of flowers,just as do the humming-birds and it is a remarkable instance;of a highly peculiar modification of an organ occurring independentlyin two widely-separated groups. In the sun-birdsthe hyoid or tongue-muscles do not extend so completely overthe head as they do in the humming-birds, so that the tongueis less extensible ;but it is constructed in exactly the sameway by the inrolling of the two laminae of which it iscomposed.The tubular tongue of the sun-birds is a special adaptivemodification acquired within the family itself, and notinherited from a remote ancestral form. This is shown bythe amount of variation this organ exhibits in different membersof the family.It is most highly developed in theArachnotheras, or spider-hunters of Asia, which are sun-birdswithout any metallic or other brilliant colouring. Thesehave the longest bills and tongues, and the most developedhyoid muscles ; they hunt much about the blossoms of palmtrees,and may frequently be seen probing the flowers whilefluttering clumsily in the air, just as if they had seen andattempted to imitate the aerial gambols of the Americanhumming-birds. The true metallic sun-birds generally clingabout the flowers with their strong feet; and they feedchiefly on minute hard insects, as do many humming-birds.There is, however, one species (Chalcoparia phoenicotis),always classed as a sun-bird, which differs entirely from therest of the species in having the tongue flat, horny, and forkedat the tip ;and its food seems to differ correspondingly, forsmall caterpillars were found in its stomach. More remotelyallied, but yet belonging to the same family, are the littleflower-peckers of the genus Diceum, which have a short billand a tongue twice split at the end ;and these feed on smallfruits, and perhaps on buds and on the pollen of flowers. The