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Birds protect themselves by always listening and watching out for danger．At the smallest sign of it，they will fly away．Birds that cannot fly are often able to swim fast，or run quickly．Some birds make themselves look bigger and more dangerous by fluting（抖动）their feathers．
Another important protection for many birds is their color．Their feathers often have same colors that match the things around their nests（巢）．Some birds change colors with the seasons．In the winter they are white to match the snow．In the summer they are brown to match the ground．
People sometimes kill birds without meaning to．When people cut down forests to build houses and factories，birds lose the homes and the food．If the birds have nowhere else to go and nothing to eat，they will die out．
Pollution may cause some birds to die．Birds that eat fish from polluted water get poison（毒）in their bodies．Then they cannot lay healthy eggs．New birds can’t be born．
Now people protect birds by passing the laws to stop hunting and pollution，by setting up some special parks where all the birds are safe from hunters，and by teaching people to care about birds rather than kill them．

It is necessary to     birds from dying out．
How do birds protect themselves?	By listening and     out for danger By fluttering their By having almost the    colors as the things around it By     colors with the season
Why do some birds die out?	They    their homes when people cut down trees．It’s difficult for them to      a hiding place from hunters． Some birds die from pollution
do people protect birds?	By passing the laws to stop     and pollution By setting up some      parks to keep birds safe By teaching people to care about birds instead of killing them