Sora Porzana carolina This information was scanned from The Birds of British Columbia (Campbell et al.), Volume II, pages 100-101. Volumes I, II and III of The Birds of British Columbia can be ordered electronically at: orders@ubcpress.ubc.ca from UBC Press in Vancouver, British Columbia.

 

Range Breeds throughout most of temperate North America from southeastern Alaska (Trapp et al. 1981), the southern Yukon and Mackenzie east to the Maritime Provinces and south through the northeastern United States to the southwestern United States to Baja California. Winters from the southern United States south to Colombia and Peru including the West Indies; occasionally farther north where marshes remain ice-free.

Status Rare to locally fairly common summer visitant from southern British Columbia, including southeastern Vancouver Island, the Fraser Lowlands, the southern interior, and the Kootenays, north through the Chilcotin-Cariboo and Nechako Lowland to the Peace and Fort Nelson lowlands. Very rare in the Bulkley and Nass basins. Casual on the Queen Charlotte Islands, the Teslin Plateau and the Chilkat Pass area. In winter, very rare visitant to the Fraser Lowlands; accidental in the Okanagan valley and on the Queen Charlotte Islands. Breeds.

Status Change No change.

Nonbreeding The Sora occurs infrequently on the northwestern Queen Charlotte Islands and the west coast of Vancouver Island, and regularly along southeastern Vancouver Island, the Fraser Lowlands and generally in suitable habitat throughout the interior to the Peace River and Boreal Forest areas. There are only a few records for the northwestern portion of the province. It has been found from sea level to 1,440 m elevation. The Sora frequents a variety of freshwater and brackish wetlands including lakes, marshes, sloughs, beaver ponds, bogs, estuaries, and sewage ponds. During migration it has been observed in atypical areas including residential lawns and gardens, sandy beaches, open fields, airport runways, city cores, and lighthouse lawns. Spring migration is usually evident in late April and early May, but may occur as early as mid-March. The autumn movement begins by early September, and most birds have left by mid-October. Occasionally, small numbers winter in the lower Fraser River valley.

Breeding Nests Eggs Young The Sora breeds from extreme southern Vancouver Island, the south mainland coast and Fraser Lowlands, and from the southern interior north through the Chilcotin-Cariboo regions and the Nechako Lowlands to the Peace Lowlands. There is an isolated record from Atlin in northwestern British Columbia. It breeds from near sea level to 1,220 m elevation, in a variety of freshwater and brackish wetland habitats including marshes, sloughs, lakes, ponds, and wet meadows, that usually contain cattail, bulrushes, and sedges. Willow swamps, marshy river and stream edges, dry grass meadows, drainage and irrigation ditches, and wet fields are used occasionally. In British Columbia, the Sora nests in wetter habitats, and more often in cattail stands, than the Virginia Rail. However, no strong niche-segregating: mechanism was found in habitat use by breeding Virginia Rails and Soras in Iowa (Johnson, R. and Dinsmore 1986).

Nests:  Most nests (92%; n=48) were in wet situations and were positioned among dense emergent vegetation, including cattail, sedges, and rushes, or in dense grasses. One nest was found in a willow clump. Most nests (86%) were attached to vegetation, above the water. Five nests were on dry ground; 2 were floating. In wet situations, nests ranged in height from 0 to= 76 cm above the water's surface with 58% between 5 and 15 cm. Most nests were woven to form a cupped platform and 2 nests were on floating mats of vegetation. Nest materials included reeds, grasses, sedges, bulrushes, and cattails with a lining of dry grasses, weed stalks or sedges. Nests were usually well concealed with vegetation bent over to form a dome. Eggs: Dates for 81 clutches ranged from 22 May to 30 July with 54% recorded between 1 and 25 June. Calculated dates indicate that eggs could be found on 1 May. Clutch size ranged from 1 to 16 eggs (1E-2,2E-5,3E-1,4E-3,5E-4, 6E-6, 7E-8, 8E-13, 9E-ll, lOE-14,11E-7,12E-1,13E-3,14E-2, 16E-1) with 65% having 8 to 11 eggs. One nest from British Columbia had an incubation period of about 17 days; Walkinshaw (1935) notes that the period ranges from 15 to 19 days. Young: Dates for 63 broods ranged from 18 May to 17 September with 56% recorded between 29 June and 25 July. Brood size ranged from 1 to 9 young (1Y-22, 2Y-16,3Y-10,4Y-5,5Y-2, 6Y 5, 7Y-1, 8Y-1, 9Y-1), with 60% having 1 or 2 young. Fledging period is about 36 days (Harrison, C. 1978).

Remarks See Virginia Rail for comments concerning the low average brood size and remarks about habitat use by breeding Soras. Walkinshaw (1940) provides noteworthy glimpses into the breeding biology of this secretive species.