He forelimbs of all the birds are modified in to wing them to fly.
{2}The bones of birds are hollow which decrises the weight hence
s which is useful fort's help to fly.{3}There shap is like streamlined and spindle.this reduces theresistance while flying.{4}The exoskeleton is of lighter.{5}There are air sacsin their body which give feathers which make them buoyancy.Hence
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Because they spend most of thier time flying in the sky and not on the land. they have wings. such many reasons have made it to adapt to aerial mode of life.
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