Answers

2015-11-11T10:36:48+05:30
Presence of wings,streamlined body.... Pneumatic bones present enables for aerial adaptations..
0
2015-11-11T10:45:14+05:30

1 ) the bones of birds are hollow which decreases the weight hence
s which is useful fort's help to fly.
2 ) there shape is like streamlined and spindle.this reduces the resistance while flying.
3 ) the forelimbs of all the birds are modified in to wing them to fly. 
4 ) the exoskeleton is of lighter.
          i hope it helps....................................................^_^
1 4 1