Until the 1970s it was not known to breed anywhere south of Canada; recent explorations have shown that it is a resident in many mountain ranges in the western United States, nesting in forest at the highest elevations. Brood size manipulations in a spatially and temporally varying environment: male Tengmalm’s owls pass increased reproductive costs to offspring. The males in this genus provide direct benefit to females such as protection, territory, and resources. Owls were accurately sexed using PCR-based molecular techniques. Lastly, size of males may play a role in mate choice in some species. Boreal owl. Oecologia, Vol. As a result, large male size (and smaller female size) would theoretically be more advantageous. The incubation period is from 25 – 32 days. Females were 4% heavier than males, but were c. 30% lighter than during the breeding season, when they carry large fat deposits and can be twice as heavy as males. The young owls fledge at 28 -36 days but remain close Boreal owls are small owls found throughout the Holarctic region. The Boreal Owl nests in woodpecker holes (Pileated and Northern Flicker) or nest boxes. However, in the boreal owl, this is not the case. The oldest boreal owl of RanuaZoo lived to be over 15 years of age. According to the IUCN Red List the total Boreal owl population size is estimated to be around 700,000-2,400,000 mature individuals. In the FMF, boreal owl nests were most frequently found in old pileated woodpecker cavities (R. Bonar, Weldwood of Canada Ltd, Hinton, Biologist, personal communication). Except when calling at night in very early spring, it is easily overlooked. 1993). Sexual size dimorphism in Tengmalm's owls Aegolius funereus outside the breeding season was investigated by trapping owls on migration during autumn. Reversed size dimorphism. LIFESPAN: According to ringing data, the oldest boreal owl has lived to 11 years of age. Egg laying dates range from the middle of March to the end of May in North America (Hayward 1994). Population number. BREEDING: Female boreal owl lays 4-6 eggs in March-April, incubation period 26-27 days and nights. Palmer 1986, Hayward et al. A rather mysterious owl of dense northern woodlands. Cavity nesting birds like the Boreal Owl require trees old enough to support the development of heart rot or other processes that allow suitably sized cavities to be formed. Scientific Classification Kingdom Animalia Phylum Chordata Class Aves Order Strigiformes Family Strigidae Genus Aegolius Scientific Name Aegolius funereus Quick Information Also known as Tengmalm’s owl, Richardson’s owl Description Size… Aegolius funereus. They are members of the typical owls group, as opposed to the barn owl grouping. Clutch size ranges from 3 – 11 eggs but 4 – 6 are more common. Boreal owls also suffer from pesticides and predation by Tawny owls and martens which kill many nesting females. Clutch size Conservation and management for Boreal Owls should provide forest types with trees of suitable size, age, species, proximity, and acreage such that the needs of this owl are met. CLASS: Aves - birds FAMILY: Strigidae - Owls SIZE: 90–220 g, wingspan: 55-60cm, females larger than males.