III ANIMAL LIFE IN THE TROPICAL FORESTS 301 
undoubtedly tend to concealment; but we have also the 
strange phenomenon of white forest birds in the tropics, a 
colour only found elsewhere among the aquatic tribes and in 
the arctic regions. Thus, we have the bell-bird of South 
America, the white pigeons and cockatoos of the East, with 
a few starlings, woodpeckers, kingfishers, and goatsuckers, 
eo are either very light-coloured or in great part pure 
white. 
But besides these strange and new and beautiful forms 
of bird life, which we have attempted to indicate as charac- 
terising the tropical regions, the traveller will soon find that 
there are hosts of dull and dingy birds, not one whit different, 
so far as colour is concerned, from the sparrows, warblers, 
and thrushes of our northern climes. He will, however, if 
observant, soon note that most of these dull colours are pro- 
tective; the groups to which they belong frequenting low 
thickets, or the ground, or the trunks of trees. He will find 
groups of birds specially adapted to certain modes of tropical 
life. Some live on ants upon the ground, others pick minute 
insects from the bark of trees; one group will devour bees 
and wasps, others prefer caterpillars; while a host of small 
birds seek for insects in the corollas of flowers. The air, the 
earth, the undergrowth, the tree-trunks, the flowers, and the 
fruits, all support their specially adapted tribes of birds. 
Each species fills a place in nature, and can only continue to 
exist so long as that place is open to it; and each has become 
what it is in every detail of form, size, structure, and even of 
colour, because it has inherited through countless ancestral 
forms all those variations which have best adapted it among 
its fellows to fill that place, and to leave behind it equally 
well adapted successors. 
REPTILES AND AMPHIBIA 
Next to the birds, or perhaps to the less observant eye 
even before them, the abundance and variety of reptiles form 
the chief characteristic of tropical nature; and the three 
groups—lizards, snakes, and frogs—comprise all that, from 
our present point of view, need be noticed. 
