Aegolius is a small genus of owls

Typical owl

True owl or Typical owl are one of the two generally accepted families of Owls, the other being the barn owls . The Sibley-Ahlquist taxonomy unites the Caprimulgiformes with the owl order; here, the typical owls are a subfamily Strigidae...

. Three of the species are restricted to the New World

New World

The New World is one of the names used for the Western Hemisphere, specifically America and sometimes Oceania . The term originated in the late 15th century, when America had been recently discovered by European explorers, expanding the geographical horizon of the people of the European middle...

, but th Boreal Owl has a circumpolar range through North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

, Eurasia

Eurasia

Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...

, the Alps

Alps

The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....

 and the Rockies

Rocky Mountains

The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...

.

The species are:

• Boreal Owl or Tegmalm's Owl, Aegolius funereus
• Northern Saw-whet Owl
  Northern Saw-whet Owl
  The Northern Saw-whet Owl is a small owl native to North America.-Description:The scientific description of one of the sub-species of this owl is attributed to the Rev. John Henry Keen who was a missionary in Canada in 1896. Adults are long with a wingspan. They can weigh from with an average...
  
  , Aegolius acadicus
• Unspotted Saw-whet Owl
  Unspotted Saw-whet Owl
  The Unspotted Saw-whet Owl, Aegolius ridgwayi, is a small owl. It is a resident breeder in the highlands of Central America from southern Mexico south to western Panama, mainly above 2500 m. it has occasionally been considered conspecific with the Northern Saw-whet Owl...
  
  , Aegolius ridgwayi
• Buff-fronted Owl
  Buff-fronted Owl
  The Buff-fronted Owl, Aegolius harrisii, is a small owl. It is a rare and local resident in the highlands of South America from Venezuela south and east to Peru, northern Argentina and northwest Paraguay...
  
  , Aegolius harrisii

These are essentially nocturnal woodland owls of temperate or colder climates; the two northern species breed in North America’s coniferous forests, and the Unspotted Saw-whet Owl and Buff-fronted Owl (Central

Central America

Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...

 and South America

South America

South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

 respectively) are species of mountain cloud or oak forests.

These are mainly resident birds, but the northern species at least will sometimes move

Bird migration

Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...

 south or to lower altitudes in autumn. The movements are difficult to monitor due to the problems of detecting these nocturnal owls outside the breeding season when they are not calling.

Aegolius owls are small, dumpy, short tailed and broad winged, with large round facial discs. The species varies from 18-27 cm in length.

These owls take mainly rodent

Rodent

Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....

s and other small mammal

Mammal

Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s as their prey, but will also feed on bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s, bat

Bat

Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...

s, insect

Insect

Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s and other invertebrates according to what is available.

The Aegolius owls are dark brown or black above, and whitish or buff below, marked with streaks or spots in the two northern forms. The head is large, with yellow eyes and a well-defined facial disc. The flight is strong, agile and direct.

Aegolius owls breed in tree holes laying several eggs. They have repetitive whistling calls in the breeding season.