All the following are natural (spontaneous) calls except for Northern Saw-whet Owl.
Barred Owl (5.30 am,Sep, Mount Desert Island, ME).
Barred Owl, screech by presumed juvenile (5.15 am,Sep, Mount Desert Island, ME).
This call is quite similar to calls made by other owl species, for example the alarm call of an adult Northern Hawk Owl (June, AK).
A pair of Great Horned Owls calling to each other shortly after dusk (Nov, PA). The begging call of young birds is a shriek, and a similar call is used by adults during the period of pair-bonding prior to the breeding season.
Another bird with a similar, but different, shriek (near dawn, Nov, PA).
A higher shriek with bill snapping and chitter call at 15s (5.30am, Oct, PA)
Great Horned Owl pair duetting, the presumed female call (first and third calls) is higher, and the presumed male call lower (Nov, PA).
Great Horned Owl barking shortly before dawn. Shortly after barking for a couple of minutes, it began hooting (Oct, PA).
Long-eared Owls hooting and mewing shortly after sunset. This was a group of at least five birds that roosted in a mesquite thicket, returning quietly as it became light in the morning (I observed them at dawn on three mornings). I visited once at dusk and the birds were more vocal then than at dawn, but the calling only lasted a few minutes.
Two birds (presumed males) hooting (6.00pm, Feb, NV)
Hooting and mew-like (alarm?) calls
Northern Saw-whet Owl wail (5.30am, Dec, PA). A short series of spontaneous wails were heard initially which appeared to coincide with calls by a pair of Great Horned Owls that hooted briefly nearby. I played back a similar call and obtained this recording, preceded by a chitter. Then two small owls flew over my head in the darkness. Habitat was deciduous woodland with a dense understory of multiflora rose, not far from an open scrubby area.
Same location, probably the same bird, briefly responding to playback of tooting (12.10am, Feb).
Possible Northern Saw-whet Owl wailing shortly before dawn (early Oct, PA). Also Swainson's Thrush calls and some minidisc noise. Eastern Screech-Owl can sound similar so this identification is tentative.
Eastern Screech-Owl tremolo, used in courtship (1.00 am, Jan, DE)
Eastern Screech-Owl whinny, used to defend territory (Dec, PA).
The Barn Owl call is a shriek (poor recording, over saltmarsh at dusk, Apr, NJ)