How endangered are local owls?
Teetering, the downy juvenile owl hops onto the edge of the cavity, wobbles its head around in a dizzying circle and furiously flaps its wings. The mother, perched on a nearby branch, keeps a watchful eye on her chick’s progress.
This fledgling Northern Spotted Owl ( Strix occidentalis ) is her hope for the future and the only addition to the dwindling population of Canada’s Northern Spotted Owls in 2005. A precipitous population decline has sparked concern among biologists and environmentalists alike.
Habitat modeling and population analysis suggests the historical population of Northern Spotted Owls in B.C. was around 500 pairs. With only six pairs and nine individual birds, the Northern Spotted Owl is the most endangered bird in Canada.
What the Northern Spotted Owl has in common with the Western Screech ( Otus kennicottii macfarlanei) and Flammulated Owl ( Otus flammeolus ), listed as endangered and threatened, respectively, is a requirement for old-growth habitat. The Northern Spotted Owl is resident in coastal and interior Douglas-fir forests and requires a home-range size of approximately 3,400 ha.
Scientists believe the Northern Spotted Owl’s need for old-growth habitat is related to reproduction, thermoregulation, and availability of prey. Their nests are in hollow chimneys, large cavities, branches, or are made from sticks. Spotted owls prey primarily on flying squirrels, pack rats, and other small mammals which can be readily found and captured in an old-growth forest. Additionally these owls have a tendency to overheat. In old-growth they can move vertically along temperature gradients to regulate their body temperature.
Flammulated Owls tend to be found in drier Douglas-fir and ponderosa pine forests in B.C.’s interior. They nest in old-growth habitat with a selection of available cavities and little undergrowth. Their breeding home-range size is 16 ha. Flammulated Owls are strictly nocturnal and prey upon moths and other insects. Due to the nature of their diet, they are migratory. They nest in British Columbia and winter in the southern USA and Mexico.
Western-Screech Owl habitat is associated with riparian areas and mature deciduous trees. In interior British Columbia, these owls occur in riparian forests containing black cottonwood, trembling aspen or water birch. The coastal sub-species is found in mixed forests of broadleaf maple, red alder, Douglas-fir and western hemlock. They are cavity-nesting individuals and their diet varies from insects to small mammals.
B.C. Hydro’s Bridge-Coastal Fish and Wildlife Restoration program, B.C. Conservation Foundation, Ministry of Environment and the St’at’imc First Nations have contributed to a study conducted by Doris Hausleitner and Vicky Young. Their objective was to inventory these three threatened and endangered owls within the B.C. Hydro footprint – land affected by dams.
Their research emphasizes the decline in the Northern Spotted Owl population in Canada and expands knowledge of the distribution of Western Screech and Flammulated owls in British Columbia. To learn more about the ecology and conservation of threatened and endangered local owls you are welcome to attend free presentations in:
Squamish: Monday, Sept. 26, 8 p.m., Brackendale Art Gallery. (Hosted by the Squamish Environmental Society.)
Whistler: Tuesday, Sept. 27 th , 7:30 p.m., Myrtle Philip Community School. (Hosted by the Whistler Naturalists.)
Pemberton: Wednesday, Sept. 28 th , 6:30 p.m., Room 111, Pemberton Community Centre.
Saturday, Oct. 1 st , 8 a.m. Whistler Bird Walk. Meet at the bottom of Lorimer Road near the Catholic Church. Everyone welcome. Please note the later, more humane, starting time.
Written by: Doris Hausleitner