Page:Popular Science Monthly Volume 30.djvu/622

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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.[1]
By WILLIAM MARSHALL.

OF all animals, birds possess the quickest motions, the most energetic 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 wooing 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 modifications 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 company 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 hunting in the bright glare of the sunlight, else, if it were too par-

  1. Address delivered before the Ornithological Society of Leipsic, February 8, 1886.