Because humans and birds are two completely different organisms and they have evolved along different evolutionary pathways.
penguins cant fly, and chickens cant propperly fly!
some birds are to big for their wings to make them fly
Penguin
Fly backwards
well, a bird that cant fly has a larger body mass than one that can
No one can because humans cant fly naturally.
If you mean human then no.humans cant fly.Humans have weight plus gravity is taking place so humans ant fly.If you mean birds they can fly because they have wings which can defy gravity and make them fly into the air.
no they cant fly because it weighs down their wings
yes, chickens are birds even if they cant fly
They cant fly...
they cant fly at night because their eye sight is only for day
Hummingbirds can fly backwards.Hover.