The cage

I am a bird 
I cannot fly 
I cannot sing 
My lungs can die 
My feathers fall 
With colors of spring 
I am a bird 
Tied to a string 
  
I am a bird 
Stuck in a cage 
Covered by bones 
Old of age 
I cannot fly 
Nor try to sing 
Covered by bones 
Feathers of spring 
  
I am a bird 
For I can see 
I live in a cage 
I am not free 
But one day I'll break 
And live in a tree