BIRDS. 



457 



proper time the down is collected and packed for export to Europe and 

 America. It takes twelve nests to furnish a pound of down, and yet 

 Greenland and Iceland each year export about three tons, the product of 

 over seventy thousand nests. 



A strange duck is the loggerhead, racehorse, or sidewheel-duck of 

 southern South America. It is a strong and swift swimmer, using its 

 webbed feet and wings in a peculiar manner, and from this fact derives its 

 common name. It is also a splendid diver, but, strange to say, when it 



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Fig. 387. — Merganser, goosander (Meryus merganser). 



becomes adult, it no longer flies, but depends upon its other powers to 

 escape from danger. 



Passing by the coots, scoters, and surf-ducks, we can only mention one 

 more group of ducks, the mergansers, or sheldrakes, all of which have a 

 more or less conspicuous crest on the crown of the head, while the lamellae 

 of the bill, instead of being used as sifting or straining organs, are converted 

 into strong teeth well adapted to hold the fishes upon which these forms 

 feed. Some make their nests by gathering leaves, straw, sedges, and the 

 like into a large and high pile, while others prefer a hollow stump or the 

 branches of some tall tree. 



In the geese the sifting-teeth are modified for grazing ; and the animals 



