Page 158 - Wonderful Creatures: Children! Have You Ever Thought ?

WONDERFUL CREATURES

GREYLAG GEESE

Greylag geese can fly at high altitudes of about 8,000 meters (5
miles). This is in fact quite a difficult task since many creatures can-

not breathe at such altitudes because of the lack of oxygen availab-
le at high altitudes. This deficiency makes respiration difficult. That

is why we can hardly breathe when we climb up a high mountain.
Flying at an altitude with a rarefied atmosphere, the bird needs to

flap its wings faster. In order to
move its wings more, the bird

will expend more oxygen,

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