书城外语科学读本(英文原版)(第4册)
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第39章 More about Birds

We have not yet finished our classification of the birds. The next order for us to consider are the waders. These birds have very long legs, for walking in the water. Hence they are sometimes known as stilt-walkers. They live on fishes, frogs, and other water animals. They have long necks to correspond with their long legs, and pointed bills for spearing their prey. They includethe snipes, plovers, lapwings, and herons of England, and the stork, crane, flamingo,buzzard, and bittern of other lands.

The swimmers form the next order.

Their distinguishing characteristic is the web between the claws. The webbed feet enable these birds to swim, and so speciallyfit them for a water life. They live in the water because they get their food out of the water. This is a large and important order; the most familiar members of it are the ducks, geese, and swans.

Many of the family are m a r i n e b i r d s . A m o n g them are the gull, penguin, p e t r e l , a n d a l b a t r o s s . The last is an immense bird, the largest of the order. It has marvellous pow ers of flight. The next order is known as runners, and includes a few large and powerfulbirds, which neither fly nor swim, but are extremely fleet on foot. The legs are exceedingly strong, and the broad thick toes are pointed forwards. As they do not fly, thesebirds have small wings; and they use the wings as balancers while running. The ostrich is the largest and most powerful of the group. It can run at the rate of twenty-six milesan hour. The emu and the

cassowary belong to the same order.

Many of our smaller birds, while they differ ver y slightly in the structure of the claws, are capable of a further useful classification according to the form of the beak or bill. The blackbird, thrush, robin, nightingale, andother well-known birds live mostly on worms, grubs, and insects. These birds have the upper mandible notched near the point, for the purpose of securing their prey. Hence they are known as tooth-billed birds. They may be regarded, on the whole, as very good friends to the farmer, in devouring the worst of his destructive enemies, although they do now and then help themselves to a little of his fruit by way of dessert.

If you have ever watched a swallow skimming swiftly over a pool on a summer evening, you must have seen that the bird always flies with its mouth wide open. The mouthis slit some distance beyond the mandibles to admit of this. But what can be the object of such structure and habits? These birds live on insects, which they catch on the wing. The open mouth presents a wide-gaping fly- trap, and the swift, skimming flight through the air is toassist them in catching their prey. The swallow, marten, swift, and goat-sucker belong to this group, which are known as wide-gaping bills.

A glance at the bill of a sparrow, a linnet, or a larkwill show that it is short and conical in shape. It has the appearance of more strength than you might expect to find in so small a bill. These birds live mostly on seeds. Their short strong beaks are specially fitted for cracking and crushing the husks of the seeds. The group are known as cone-shaped bills.

The humming-birds of South America represent anothergroup. They are all tiny little birds, with remarkably gorgeous plumage, although some of them are scarcely bigger than a bee. They frequent the flowers, some say for the sake of the insects in them, others for the sake of the sweet juice or nectar which they contain. Whether for one or both of these purposes, the bills have no hard work to do, and hence they are soft and slender. The group are known as the slender bills.

Lesson 41