Vesper sparrow (Pooecetes gramineus affinis) COSEWIC assessment and status report: chapter 4

Distribution

Global range

Vesper Sparrows are widespread across North America. They reach the northern extent of their breeding range in the southern Northwest Territories, and are found from British Columbia to Nova Scotia south to California, Arizona and Virginia (Figure 1; Jones and Cornely 2002).

The Coastal Vesper Sparrow, P. g. affinis, forms a disjunct population in the Pacific Northwest, separated from the core population (i.e., of P. g. gramineus, P. g. confinis, and P. g. altus) by the densely forested Cascade Mountain Range. This subspecies breeds locally on southeastern Vancouver Island, and in the lower Fraser River valley (at least formerly), south through western Washington and Oregon to extreme northwestern California (Figure 1). It is accepted by most authorities that the Coastal Vesper Sparrow is the only subspecies found west of the Cascades (AOU 1957; Pyle 1997; Cannings 1998; Rogers 2000; Campbell et al. 2001; Jones and Cornely 2002; Altman 2003).

Figure 1. The breeding range of the Coastal Vesper Sparrow, P. g. affinis (red) and other subspecies (P. g. gramineus, P. g. confinis, and P. g. altus, yellow); adapted from Jones and Cornely (2002).

Figure 1. The breeding range of the Coastal Vesper Sparrow, P. g. affinis (red) and other subspecies (P. g. gramineus,P. g. confinis, and P. g. altus, yellow); adapted from Jones and Cornely (2002).

Although taxonomic work has not been done on the breeding population in coastal British Columbia, it is accepted that these birds are P. g.affinis (Fraser et al. 1999), based on the known distribution of that race in Washington and Oregon (Campbell et al. 2001). Coastal Vesper Sparrows breed on San Juan Island, Washington, less than 20 km from southern Vancouver Island (Rogers 2000), while the nearest P. g. confinis population is several hundred kilometres to the east on the other side of the Cascade Range and Coast Mountains (Campbell et al. 2001; Jones and Cornely 2002).

Vesper Sparrows winter across the southern United States, south through Mexico to central Guatemala (Jones and Cornely 2002). The Coastal Vesper Sparrows winters from central California west of the Sierra Nevadas to northwestern Baja California (AOU 1957).

Canadian range

All subspecies

The Vesper Sparrow breeds in grassland habitats from British Columbia east to Nova Scotia. The subspecies P. g. confinis breeds from the interior of British Columbia, east of the Cascades and Coast Mountains north through the Chilcotin and Cariboo Plateaus to the Peace Lowlands, across Alberta, and into the southern extreme of the Northwest Territories. Further east the range dips to the south across southern Saskatchewan and Manitoba to southwestern Ontario. Further east, Vesper Sparrows of the gramineus subspecies breed across southern Ontario through southern Quebec, including the Gaspé Peninsula, and in parts of New Brunswick, Nova Scotia and Prince Edward Island (Jones and Cornely 2002).

Coastal Vesper Sparrow

Within Canada, the Coastal Vesper Sparrow has been found only on southeastern Vancouver Island and in the lower Fraser River valley. Historically, Vesper Sparrows have been reported during the breeding season on Vancouver Island from the Englishman River estuary in the north to Cobble Meadows and Mill Bay in the south and locally in the Fraser Lowland on the southwest mainland coast (Campbell et al. 2001; Beauchesne 2002b). Although records of this species were sporadic through the early 1900s, the following occurrence data suggest that this species has been present in the region for more than 50 years: breeding season records on Vancouver Island from 1890, 1891, and 1892; nesting in New Westminster, 1938; breeding season observations in the Chilliwack region, 1944 (Campbell et al. 2001). Additional records in the last 50 years include: breeding season observations on Vancouver Island, 1957; breeding season observations in the Chilliwack region, 1961, 1962, and 1968; nesting on Iona Island (Fraser Delta), 1968; consistent breeding season records for Vancouver Island from 1971 to present; additional sporadic records from the Fraser Valley from the 1970s to present (Campbell et al. 2001; Beauchesne 2002b).

Currently, the Coastal Vesper Sparrow is considered a very rare summer visitor in the Fraser Lowlands (M. McNicholl, pers. comm.). The only known extant breeding population is located on Vancouver Island about 20 km south of Nanaimo at the Nanaimo Airport (Beauchesne 2002a, 2003, 2004).

Figure 2. Breeding range of the Coastal Vesper Sparrow, shown in light green; Nanaimoairport site shown as red dot. The interior subspecies of the Vesper Sparrow (P. g. confinis) breeds in grassland areas shown in the satellite image as a buff colour, separated from the coastal grasslands by high mountains (dark green and white).

Figure 2. Breeding range of the Coastal Vesper Sparrow, shown in light green;

Outside of the breeding season, Vesper Sparrows have been recorded on Vancouver Island and the Gulf Islands from Cortes Island south to Victoria including Rocky Point and the Victoria Airport area (Fraser et al. 1999; Beauchesne 2002b). The origin of these birds is unknown.

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