The title explains what the poem is about.

On a Cape May Warbler Who
Flew Against My Window

Eamon Grennan

She's stopped in her southern tracks
Brought haply to this hard knock
When she shoots from the tall spruce
And snaps her neck on the glass.

From the fall grass I gather her
And give her to my silent children
Who give her a decent burial
Under the dogwood in the garden.

They lay their gifs in the grave:
Matches, a clothes-peg, a coin;
Fire paper for her, sprinkle her
With water, fold earth over her.

She is out of her element forever
Who was air's high-spirited daughter;
What guardian wings can I conjure
Over my own young, their migrations?

The children retreat indoors.
Shadows flicker in the tall spruce.
Small birds flicker like shadows —
Ghosts come nest in my branches.

from What Light There Is and Other Poems, 1988
North Point Press