Find an Idom in The Sandpiper Poem by Celia Thaxter. Any help is appreciated!

Across the lonely beach we flit,
One little sandpiper and I;
And fast I gather, bit by bit,
The scattered drift-wood, bleached and dry.
The wild waves reach their hands for it, The wild wind raves, the tide runs high,
As up and down the beach we flit,
One little sandpiper and I. X

Above our heads the sullen clouds
Scud, black and swift, across the sky
Like silent ghosts in misty shrouds
Stand out the white lighthouses high. Almost as far as eye can reach I see the close-reefed vessels fly,
As fast we flit along the beach
One little sandpiper and I.

I watch him as he skims along,
Uttering his sweet and mournful cry;
He starts not at my fitful song,
Or flash of fluttering drapery.
He has no thought of any wrong;
He scans me with a fearless eye.
Staunch friends are we, well tried and strong,
The little sandpiper and I.

Comrade, where wilt thou be to-night
When the loosed storm breaks furiously? My driftwood fire will burn so bright!
To what warm shelter canst thou fly?
I do not fear for thee, though wroth
The tempest rushes through the sky:
For are we not God's children both,
Thou, little sandpiper, and I?​