SOME NOTES ON NEBRASKA BIRDS. 51 



In size birds vary greatly, rauging from the miuutest humming-bird, 

 which is scarcely larger than a bumble-bee, to the largest ostrich that 

 stands higher than the tallest mau. Yet in size, color, form and 

 habits they are perfectly fitted for the respective places which each 

 fills in the vast sea of life about them. 



Unlike most other animals, birds are much less restricted in their 

 distribution over the earth's surface. This is undoubtedly due to their 

 power of locomotion, which enables them "to choose their climates 

 and their seasons, — thus avoiding, in a great measure, one of the most 

 destructive checks upon the multiplication of animals." And, by the 

 way, the organs which they possess for locomoting the air are very 

 characteristic of these creatures alone. They are made up of a series 

 of modified scales, or, perhaps more properly speaking, hairs that 

 grow out of the front pair of limbs and the tail. Consequently it is 

 that in birds the law of migration reaches its climax. Directly related 

 to this trait, and largely regulating its diiferent phases, are such feat- 

 ures as chauge in the seasons with their accompanying variations in 

 heat and cold, food supply, reproduction, moulting of feathers, etc. 



When a|)plied to the entire feathered tribe, bird migrations are cer- 

 tainly more of a study than one would at first suppose. Hardly any 

 two species seem to possess this trait in the same degree, nor to act in 

 precisely the same manner during its performance. Some of them make 

 the change from one region to another so gradually that the movement 

 is barely noticed. Others remain either in the sunny south, where 

 they revel among showy flowers and the giant trees of tropical forests 

 dressed in their festoons of clinging vines and deep green mosses, or in 

 the northland, where the memories of their wooings, and, more re- 

 cently, the caring for their hungry little ones, occupied the long sum- 

 mer days. At last the moment for action has come, and they are up 

 and away. Some birds travel in flocks, some by families, and others 

 in pairs, or singly, as the case may be. These journeys are made with 

 some only during the day-time, while others travel only by night, and 

 still others move along as necessity demands. In spring they go north- 

 ward, in fall towards the south. Some migrate principally for breed- 

 ing, others on account of food supply, all of them seemingly of a ne- 

 cessity. During their migrations, as well as at other times, the speed 

 attained in their flights by some birds is simply marvelous, if not al- 

 most incredible. Some ducks are said to travel at the rate of two 



