Not all birds can fly,but the birds who can fly it's because birds use there strong breast muscles to flap their wings and give them the thurst to move through the air and fly.(Pinguins can't fly)
Birds can fly because of there special wing bone structure shaped like a honeycomb. They can fly because they are so incredibly light. There are more than 30 flightless bird species. For example... an ostrich, and emu.
