It is found in Costa Rica, El Salvador, Guatemala, Mexico, and Panama.

The Clements taxonomy and BirdLife International's Handbook of the Birds of the World (HBW) assign it three subspecies, the nominate A. r. ridgwayi, A. r. tacanensis, and A. r. rostratus.

Its facial disk is brown with a narrow white border; the lores, chin, and "eyebrows" are whitish.

[6] The nominate subspecies of unspotted saw-whet owl is found from central Costa Rica into western Panama.

It nests in cavities, either natural or made by woodpeckers, and is thought to lay five or six eggs.

Both sexes give "a surprisingly loud shriek and a shrill short chipper".

The call of tree frogs of genus Anotheca is extremely similar to the owl's song and easily confused with it.

[6] The IUCN originally assessed the unspotted saw-whet owl as Near Threatened but since 2004 has rated it as being of Least Concern.