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　　A type of bird that is now extinct(消失)is the passenger pigeon．The passenger pigeon lived in the eastern part of North America．Scientists believe that in the year 1500 there were as many as five billion of these birds living from Canada to the Gulf of Mexico．They flew at great speeds and would travel to many places to look for food．Passenger pigeons grew to be about 16 inches long．

　　Settlers who came to North America killed the passenger pigeon for food and for its feathers．The forests where they lived were cut down to clear the land for farming．Because the passenger pigeon laid only one egg at a time, their population did not grow quickly．The last passenger pigeon died at Cincinnati Zoological Gardens in 1914．

　　Another type of bird that has become extint is the dodo．The dodo lived on an island called Mauritius in the Indian Ocean．It had short, stubby legs and wings and a large curved beak．The dodo was about the size of a large turkey．It was acturally related to the pigeon, but it could not fly．Like the passenger pigeon it laid only one egg at a time．Dodos became extinct because they were eaten by sailors and animals, such as pigs and monkeys, that the sailors brought to the island．The dodo is believed to have died out in 1680．

　　Another flightless bird that has become extinct is the moa．The moa lived on the North and South Islands of New Zealand．Like the dodo, the moa’s legs were shorter, but some of these birds grew to be more than ten feet tall．And the causes of its extinction is the same as the dodo’s．The moa is believed to have died out sometime during the 1700s．

1．Were there many passenger pigeon in the year 1500?

2．When did the last passenger pigeon die at Cincinnati Zoological Gardens?

3．Where did the dodo live before it died out?

4．How many kinds of birds have died out in the passage?

5．Why have these birds died out?