Acadian owl, Blind owl, Kirkland's owl, Saw-filer, Sparrow owl, White-fronted owl, Farmland owl, Little Nightbird, Queen Charlotte owl, Whet-saw owl
The Northern saw-whet owl (Aegolius acadicus) is a small owl native to North America. Saw-whet owls are one of the smallest owl species in North America. These adorable owls can be found in dense thickets, often at eye level, and are often in danger of being preyed upon by larger owls and raptors. They are quite common but hard to spot.
Northern saw-whet owls are similar in size to the American robin. They have a round, light, white face with brown and cream streaks; they also have dark beak and yellow eyes. Juveniles have a dark brown head and wings, and a tawny rust-colored breast and belly. There is also a distinct white, Y-shaped coloration between their eyes. The juveniles can often be confused with the juvenile Boreal owls. Northern saw-whet owls resemble the Short-eared owl, because they also lack ear tufts, but are much smaller. The underparts are pale with dark shaded areas; the upper parts are brown or reddish with white spots. These owls have porphyrin pigments in their flight feathers. When exposed to a UV light the ventral side of the wing, feathers will fluoresce a neon pink. This is used in order to estimate molt and age in adult northern saw-whet owls.
Northern saw-whet owls are found in most of North America including southeastern and southcentral Alaska, southern Canada, most of the United States, and the central mountains in Mexico. Some populations are permanent residents, while others may migrate south in winter or move down from higher elevations. These birds inhabit coniferous forests, sometimes mixed or deciduous woods, and also love riparian areas because of the abundance of prey there.
These birds are strictly nocturnal and solitary. They live in tree cavities and old nests made by other small raptors. During the day Northern saw-whet owls usually roost in dense foliage, close to the end of a branch. At night, they hunt waiting on a high perch and when the prey is spotted they swoop down to capture it with talons. Northern saw-whet owls are generally silent and vocalize mostly during the breeding season making a repeated tooting whistle sound; they usually make these sounds to find a mate. Some say they sound like a saw being sharpened on a whetstone. Other vocalizations include the Advertising call, the Rapid call, Whine, Ksew call, Tssst call, Squeaks, Twittering call, Guttural chuck, and begging calls of nestlings. Non-vocal sounds such as bill snapping are used as a warning call by adults, juveniles, and nestlings usually when approached up close or when in the hand.
Northern saw-whet owls are carnivores. They mainly eat small mammals and also supplement their diet with small birds, with passerines such as swallows, sparrows, kinglets, and chickadees. On the Pacific coast, these owls may also eat crustaceans, frogs, and aquatic insects.
Northern saw-whet owls are serially monogamous and form pairs that last only during one breeding season. However, at times when prey is abundant males may mate with more than one female (polygynous behavior). Females sometimes may also leave their partners with the nestlings and mate with another male and raise a second brood (polyandrous behavior). Northern saw-whet owls breed between March and July. During this time males will often sing from a nest sight and cache food in nests in order to attract a female. Pairs nest in natural tree cavities, in old woodpecker holes, and also in nest boxes. Females lay about 4-6 white-colored eggs and incubate them for about 26-28 days alone. During this period the male does the hunting. Owlets hatch altricial; they are blind a covered with white dawn. The parents feed and protect their young about 4 to 5 weeks of age until they fledge and are able to fly. Owlets become independent when they are 6-8 weeks old and start to breed at one year of age.
Northern saw-whet owls are quite common but declines occur due to habitat loss and competition with Boreal owls, starlings, and squirrels for nest cavities. These small birds are also in danger of being preyed upon by larger owls and raptors.
According to the IUCN Red List, the total population size of the Northern saw-whet owl is around 2,000,000 mature individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List but its numbers today are decreasing.
