Why do YOU think some birds can fly?

They're small enough.
% (36 votes)
They're light enough.
% (110 votes)
They have big wings.
% (69 votes)
They have big feathers.
% (41 votes)
They have hollow bones.
% (156 votes)
They have a special muscle.
% (136 votes)
They have hollow bones.
28.47% (156 votes)
They have a special muscle.
24.82% (136 votes)
They're light enough.
20.07% (110 votes)
They have big wings.
12.59% (69 votes)
They have big feathers.
7.48% (41 votes)
They're small enough.
6.57% (36 votes)
Back to poll
548 votes