BIRDS AND THEIR DAILY BREAD. 609 



and swimmers. Of the fourteen families of the former groups, four 

 are quite and one nearly cosmopolitan ; and of the eight families of 

 the latter group, among which are some powerful fliers, only three have 

 not a universal diffusion ; and the two groups exhibit more genera 

 occurring over nearly the whole earth (eighteen out of ninety-six and 

 eleven out of seventy-nine) than all the other families of birds put 

 together. But we can not overlook the fact that some of these genera 

 stand on a very feeble footing. 



It is interesting to observe that, in the other orders of birds, those 

 kinds that live on fish are very widely spread. Thus, the kingfishers 

 are cosmopolitan, and the genus Ceryle, which Brehm says includes 

 " the strongest, most active, and most ravenous members of the fam- 

 ily," is especially wide-spread, and is without representatives only in 

 Australia, Madagascar, Europe, and Northern Asia. The nine not 

 greatly differing species of water-ousel, whose habits are much like 

 those of the true kingfishers, are very widely diffused wherever there 

 are cool, clear, and rapid mountain-brooks. 



The distribution is less wide of such birds as live principally on 

 land-invertebrates, especially on articulates. Their occurrence is largely 

 dependent, like that of plant-feeders, indirectly but intimately on the 

 character of the vegetation ; and those forms among them which, like 

 titmice, wrens, and woodpeckers, live on insects at rest, as well as on 

 eggs and pupse, or on larva?, either concealed or living in wood, and 

 changing place but little, have the most extensive range ; and, since 

 larva? pass the winter in one of the forms mentioned, they are perma- 

 nent residents in temperate climates. In the measure that a bird pur- 

 sues perfect insects, particularly those which fly, it becomes possible 

 for it to be an established inhabitant only in warm climates. To dwell 

 in colder regions, if it usually refuses vegetable food, it must be a good 

 fiier, and is then compelled to go away on the approach of the cold 

 season and the accompanying disappearance of its food. 



The presence of plant-eating birds is still more predominantly de- 

 pendent on their food ; and it is a matter of interest to observe how 

 the opening out of the vegetation of a country reacts upon its ornithic 

 population. Africa, wherever it is not wooded or desert, the Europeo- 

 Asiatic steppes, and the prairies of America, are covered with grass 

 and other mealy-seeded herbs, and are also the dwelling-places of hosts 

 of weaver-birds, larks, and other grain-eaters, the flocks of whose nu- 

 merous species are numbered by the thousand ; and wherever they can 

 find their food in winter, they abide. Groups of berry-bearing plants 

 cover extensive regions of the north, and follow, as they stretch down 

 toward the south, the cooler regions of the higher mountains ; and in 

 their suite we find everywhere, in the tundras of Siberia, on the slopes 

 of the Himalayas, and in the Peruvian Andes, fruit-eating birds of 

 similar genera. In the fruit-rich woods of the tropics, especially of 

 South America, more than half of the native birds, though represent- 

 vol. xxx. — 39 



