As I came to the edge of the woods,
Thrush music -- hark!
Now if it was dusk outside,
Inside it was dark.
Too dark in the woods for a bird

 Frost probably chose the thrush because he had experience  listening to their clarinet-like tones every summer in Vermont.  
 The thrush also appears in a number of other famous poems in English, including Thomas Hardy’s  “The Darkling Thrush”  (in which it’s an ambiguous symbol of hope) and Walt Whitman’s  “When Lilacs Last in the Dooryard Bloom’d,”  where it’s associated with both poetry and death: 
 
 Solitary the thrush, The hermit withdrawn to himself, avoiding the settlements, Sings by himself a song. 
 Song of the bleeding throat, Death’s outlet song of life (for well dear brother I know, If thou wast not granted to sing thou would'st surely die). 

Come In