600 THE POPULAR SCIENCE MONTHLY. 



has fallen the blight of a terrible winter, never yet removed ; and all 

 struggle on among the chilly mountains and the northern snow-fields 

 in virtue of that very constitution and character which they derived 

 from their ancestors of the Glacial Age. 



BIRDS AND THEIR DAILY BREAD.* 



By WILLIAM MARSHALL. 



OF all animals, birds possess the quickest motions, the most ener- 

 getic respiration, and the warmest blood, and they consequently 

 undergo the most rapid change of substance, and need the most food. 

 Although few creatures are so pleasing to the aesthetic tastes of a 

 poetically inclined person as birds, the breeder knows that most of 

 them are to be looked upon as hearty or excessive eaters. Any one 

 who closely observes birds and their conduct will soon remark that all 

 their thoughts and efforts, aside from the few days they spend in woo- 

 ing and their short periods of resting, are directed to getting something 

 to eat. With what restless earnestness do titmice plunge through the 

 bushes and the trees ! Not a leaf is uninvestigated, every chink in the 

 bark is examined for whatever eatable it may be hiding, and a sharp 

 look is cast into every joint of a branch. How industriously does the 

 ousel turn and thrash the leaves on the ground of the woods all the 

 day long, spying its game with a glance of its sharp eye, and snapping 

 it up on the instant ! After observing a few such incidents we can 

 easily believe the stories that are related of the fish-eating powers of 

 the cormorant, and of the fruit-eating birds that are able to consume 

 three times their weight every day. 



The result of this property of enormous appetite is an intensified 

 activity in the competition for food among birds, and the structure of 

 their bodies and their habits have undergone considerable modifica- 

 tions in consequence of the fact. It is this which has compelled some 

 birds that should be, according to common poetic conception, creatures 

 of the day, to hunt their prey by night. There are many transitions 

 or connecting links between day-birds and night-birds. Day-birds 

 may sometimes be seen pursuing their prey till late in the twilight ; 

 and, on the other hand, night-birds, impelled by hunger, will leave 

 their hiding-places while it is still day. Chimney-swallows are often 

 observed of summer evenings circling around high in the air, in com- 

 pany with the bats. The corn-kite is likewise fond of hunting in the 

 dusk, and is late in retiring to its roost. Several owls do not shrink 

 from the clear light, and the Strix coquimba of the Chilian coast hunts 

 only by day. Most evidently the northern snow-owl must do its 

 limiting in the bright glare of the sunlight, else, if it were too par- 



* Address delivered before the Ornithological Society of Leipsic, February 3, 1886. 



