If there were no birds we would first of all die. Birds eat millions of insects in there lifetime and millions and millions of insects are born in one month. If there were no birds there would be infinite nos. of insects. Secondly some birds help to pollinate flowers.
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Birds like owls,hawks,eagles,falcons,etc help in control of rodents and keeping the environment clean by eating the dead remains of different animals .they help to control insects . they help in dispersion. they eat the fruits and throw the seed in some place which help in the formation of new plant at that place.
 hope it may help u . 

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