Short-eared owl (Asio flammeus) COSEWIC assessment and status report: chapter 4

Distribution

Global range

Short-eared Owls have one of the largest ranges among owls, breeding in open habitats across the North Temperate zone, in South America, and a large number of Oceanic islands including the Greater Antilles, the Galapagos archipelago, and Hawaii. Although the breeding range in North America is broad (Figure 1), the species occurs irregularly within this range, settling to breed in suitable unforested habitats with concentrations of small mammals.

Figure 1. Range of the Short-eared Owl in North America (Modified from Wiggins et al. 2006). Note that within the broad range depicted, Short-eared Owls are highly nomadic, nesting and wintering in areas with local outbreaks ofMicrotus voles and other small rodents, and largely avoiding forested areas. Short-eared Owls are absent from forested and mountainous areas of the map.

Figure 1.   Range of the Short-eared Owl in North America(Modified from Wiggins et al. 2006).

Canadian range

In Canada, Short-eared Owls breed in all provinces and territories, but are most common in the Prairie provinces (AB, SK, MB) and along the arctic coast. During winter, the species is a regular resident in open habitats along the extreme southern British Columbia coast and in southern Ontario, an occasional resident in coastal areas of Atlantic Canada, and also occurs sporadically in the Prairie provinces where the number of wintering individuals fluctuates strongly among years.

The species’ current regional distribution within Canada is as follows:

Yukon Territory

The Short-eared Owl is an uncommon summer resident and migrant in the Yukon, with strong fluctuations in the number of breeding pairs from year to year (Sinclair et al. 2003). Breeding has been documented along the coastal plain and inland tundra areas, with observations during summer suggesting that they may also breed at scattered sites in the southern Yukon. Fall migration occurs from late August to late October (Sinclair et al. 2003, C. Eckert, pers. comm.).

Northwest Territories

Although they may breed in suitable habitat throughout the Northwest Territories, Short-eared Owls are most commonly found breeding on coastal tundra habitat (http://www.enr.gov.nt.ca/_live/pages/wpPages/Short-eared_Owls.aspx).

Nunavut

As in the Northwest Territories Short-eared Owls are widely distributed in Nunavut, with higher concentrations in coastal tundra areas during years of lemming outbreaks.

British Columbia

The breeding range includes the Fraser River valley in the lower mainland, the Okanagan Valley north to the Thompson-Chilcotin region, and the Peace River lowlands in the northeast (Campbell et al. 1990). Summer records from the Stikine River valley and the Chilkat Pass area suggest at least occasional breeding in the northwestern portion of the province. Wintering birds are largely restricted to the Lower Mainland and southern interior valleys.

Alberta

The breeding range includes most of the grassland region of the southwest, the parklands, and the Peace River region (Semenchuk 1992). Scattered summer records also suggest breeding in suitable (open) habitat in the southern boreal forest region. Winter records are largely restricted to the grasslands region and are highly variable among years.

Saskatchewan

Recent atlas work documented widespread breeding across southern and central portions of the province, with a few scattered summer records north into the boreal forest zone (Smith 1996). During winter, Short-eared Owls are occasionally found north to the southern fringe of the boreal forest.

Manitoba

Short-eared Owls were formerly common breeders in the southern third of the province, noted as abundant in the Portage la Prairie area (Thompson 1891). They are now noted as erratic breeders on the northern tundra and in open habitats in the southern portion of the province (Taylor 2003).

Ontario

Preliminary data from the recently updated Ontario Breeding Bird Atlas map (Figure 2; Birds Ontario, unpubl. data) shows breeding records concentrated on the Hudson Bay coastline near Winisk, along the Ottawa River in eastern Ontario, in widely scattered localities elsewhere in southern Ontario, and in the far west of the province in the Rainy River District. In general, the atlas data show a similar distribution between the two periods, although an increase is shown when effort is accounted for. It is important to note that the apparent lack of records from (interior) northern lowland areas is likely the result of reduced survey efforts there, rather than an absence of owls.

Figure 2. Comparative breeding season distributions of Short-eared Owl in Ontario, based upon recent (2000-2005; upper figure; Birds Ontario, unpubl. data) and 1980s breeding bird atlas records (Cadman et al. 1987). In the upper figure, the grey dots indicate squares in which the species was found in the first atlas project, but not in the second; yellow dots indicate squares in which the species was found during the second atlas and not the first.

Figure 2.   Comparative breeding season distributions of Short-eared Owl in Ontario, based upon recent (2000-2005; upper figure; Birds Ontario, unpubl. data) and 1980s breeding bird atlas records (Cadman et al. 1987).

Quebec

Although breeding season records exist over most the province, records are concentrated along the St. Lawrence estuary and the Saguenay-Lac Saint-Jean Region in the southwestern portion of the province (Cyr and Larivée 1995, LaGauthier and Aubry 1996).

New Brunswick

All recently confirmed breeding records have been from coastal sites (Erskine 1992). An important historical breeding site is the Tantramar marshes near the New Brunswick/Nova Scotia border (Squires 1952, Erskine 1992).

Nova Scotia

The most recent data available are from the Maritimes Breeding Bird Atlas project, which resulted in relatively few records of Short-eared Owls, including three confirmed breeding records along the coast (Erskine 1992).

Prince Edward Island

The Maritimes Breeding Bird Atlas found three records for Prince Edward Island, two (including one confirmed nesting record) on the northern coast, and one probable breeding record inland (Erskine 1992).

Newfoundlandand Labrador

Short-eared Owls are thought to have been widespread breeders in Newfoundland and Labrador, with the vast majority of historical records at coastal sites (Schmelzer 2005). The most recent records in Newfoundland and Labrador come from dedicated Short-eared Owl surveys during July 2003. Only two owls were seen during surveys in Newfoundland, while a total of 11 individuals were seen along the Labrador coast (Schmelzer 2005).

Page details

Date modified: