The unspotted saw-whet owl (Aegolius ridgwayi) is a small "typical owl" in subfamily Surniinae. It is found in Costa Rica, El Salvador, Guatemala, Mexico, and Panama. Taxonomy and systematics The unspotted saw-whet owl's taxonomy is unsettled. The International Ornithological Committee (IOC) treats it as monotypic. 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. HBW's assignment is provisional. A. r. tacanensis and A. r. rostratus were each described from a single specimen. The unspotted saw-whet owl and the northern saw-whet owl (A. acadicus) form a superspecies and some authors have proposed that they are a single species. Description The unspotted saw-whet owl is long and weighs about . Its upperparts, throat, and upper breast are plain sepia brown and the lower breast and belly plain cinnamon buff. The tail is a darker brown and the wings generally a grayer brown. Its facial disk is brown with a narrow white border; the lores, chin, and "eyebrows" are whitish. It has yellow eyes. The two putative subspecies other than the nominate differ only slightly from it. Distribution and habitat The nominate subspecies of unspotted saw-whet owl is found from central Costa Rica into western Panama. A. r. tacanensis is found in Mexico's Chiapas state. A. r. rostratus is found in Guatemala and northwestern El Salvador. The species inhabits humid temperate montane forest. Vegetation communities include humid oak forest, cloudforest, and pine-oak forest. It generally stays in the forest canopy but can be found in more open areas with scattered trees but close to forest edges. In elevation it ranges between in the northern part of its range, between in Costa Rica, and between in Panama. Behavior The unspotted saw-whet owl is nocturnal. It is usually solitary, except in the breeding season, and is thought to be territorial. Its flight is described as "fluttery, agile, with quick wingbeats." Movement The unspotted saw-whet owl is resident throughout its range. Feeding The unspotted saw-whet owl's diet has not been detailed. Small mammals such as shrews and rodents are thought to be its primary prey. It is also thought to take birds and bats. Breeding The unspotted saw-whet owl's breeding phenology is not well known. Its breeding season appears to span between at least March and July. It nests in cavities, either natural or made