CHOICE OF A HABITAT. 
83 
denizens of the air, and perform the longest journeys witli the greatest 
apparent ease. The goatsuckers, nearly allied to them, but of weaker 
power, and with largely developed eyes, are semi-nocturnal in their 
habits; sometimes flying in the evening in company with the swallows, 
but more frequently settling on the ground, seizing their prey by 
short flights from it, and then returning to the same spot. Again : 
the flycatchers, which are short- winged but strong-legged birds, cannot 
vie with the swallow in ease and rapidity of flight. They generally 
perch on a bare branch, and bide their time until unwary insects veer 
within reach of a short SAVoop, when their broad bills and wide gape 
soon play havoc with them. The bills of the jacamar, on the other 
hand, are long and pointed, yet their habits are similar to those of the 
preceding ; they sit on branches in open parts of the forest, from thence 
flying after insects, which they catch in their aerial courses, and return- 
ing to their former station to enjoy the results of their foray. The same 
is the case with the trogons, whose bill is strong and serrated ; while 
the tiny humming-birds, though they generally seek their food in the 
dewy chalices of the flowers, often capture insects on the wing, like 
any other fissirostral bird. 
All this is true ; but still the fact remains that, in his choice of a 
habitat, the bird is necessarily guided by the character of the food it 
offers. Frugivorous birds are not found in sandy African deserts. 
The insectivorous birds of the virgin forests would starve in our English 
fields and pastures. And it seems equally certain that, on the whole, 
the structure of the bird is adapted to the food on which he lives. The 
bill of the jacamar may diff'er from that of the goatsucker, but both 
bills are fitted for the capture of insects ; and both are wholly dissimilar 
to those of the parrots, the toucans, and other fruit-eaters. We may 
not, and we do not, know all the laws which govern the geographical 
distribution of animals ; but certain leading principles are sufficiently 
obvious. 
Mr. Bates, in describing the bill of a toucan, arrives at a very 
different conclusion to that of Mr. Wallace — seeing in it a remarkable 
illustration of perfect adaptation of means to an end. All the 
toucans are famous for the great size and lightness of their beaks. 
