Chatter in the Eaves

A muted stirring in the greyness
Soft chatter in the eaves
Restless whistles that are muffled
No sound of a breeze
A sharper sound grates in urgency
Punctuates the line
Pulsations on a single note 
The caller is defined
In minutes the sky is lightened
Grey turns to tinge of blue
Day hangs briefly in a balance
Night’s silence ensues.