Northern saw-whet Owl (Aegolius acadicus)

Birds of North Carolina – Northern saw-whet Owl (Carolina Bird Club)
Northern saw-whet Owls breed in the higher elevations of North Carolina’s mountains and are a winter resident over most of the region. Breeding habitat is typically where some hardwoods are mixed with spruce and fir; however, some birds do occur at lower elevations, even where such conifers are lacking. In winter, the species roosts in thick cover, and feeds in small wooded openings, though much still remains unknown about winter season habitats and foraging behavior, in part because birds have been found in a very wide range of habitats — even in pocosins!

All About Birds – Northern saw-whet Owl (Cornell Lab of Ornithology)
One of the most common owls in forests across northern North America (and across the U.S. in winter), saw-whets are highly nocturnal and seldom seen. Their high-pitched too-too-too call is a common evening sound in evergreen mountain forests from January through May.

Northern saw-whet Owl Song and Calls (Cornell Lab of Ornithology)
Male Northern saw-whet Owls calling to advertise their territory can be heard up to half a mile away. Other males respond with a softer, faster, lower version of the song. Females also use a version of the song during courtship.

Audubon Guide to North American Birds – Northern saw whet Owl
Late at night in the breeding season, males give a rhythmic tooting song that may go on for hours with scarcely a break. The bird was named for this song, which reminded settlers of the sound of a whetstone sharpening a saw.

Northern Saw-whet Owl (Tennessee Wildlife Resources Agency)
The Northern Saw-whet Owl breeds in the forests of the west and the northeast. The mountains of Tennessee and North Carolina represent the southern limit of that range. In winter the northern-most breeders migrate southward across the United States.  It primarily eats woodland mice, but occasionally some small birds and large insects.