Somenos Marsh is located in southeastern Vancouver Island, a short distance north of downtown Duncan. The marsh system is 200 hectares in size, and includes Somenos Lake and four creeks. Grass and shrub habitats are common, and willows are interspersed throughout. The farmlands become flooded marsh-like areas in winter and spring. Water levels can rise as much as 2.5 m in winter. Some of the rare flora and fauna found here include the Vancouver Island Ringlet, Prairie Lupine, Yellow Montane Violet, and Garry Oaks growing in deep soils. The IBA includes the wildlife refuge and a herony that is on the west side of the Trans Canada Highway.
Somenos Lake is known for the high number of Trumpeter Swans that over-winter each year. Christmas Bird Count data show that up to 1,000 birds can be present roosting and feeding in the lake and flooded wetlands. This represents about 5% of the worlds population of Trumpeter Swans, and is the second largest over-wintering number of Trumpeter Swans on Vancouver Island. In the first half of the 1990s, typically about 600 Trumpeter Swans wintered in the marsh and lake. But, because the Trumpeter Swan population has been increasing in recent years, more birds have been seen since then.
Also, just over 1% (25 pairs) of the Canadian population of the nationally vulnerable fannini subspecies of the Great Blue Heron breed and winter here. The actual nesting site is on the west side of the Trans Canada Highway, although the birds feed in the lake and marsh.
Somenos Lake is a good spring, fall and winter location for waterfowl. During the winter, there are concentrations of up to 2,000 waterfowl on the lake and surrounding fields. In addition, two pairs of Barn Owls nest in the area; the British Columbia population of this species is nationally vulnerable. Two hundred species have been recorded in the refuge in total including passing rarities such as Tufted Duck, Eurasian Wigeon, Black-crowned Night-Heron, Great Egret and Black-throated Sparrow.
BirdLife International (2019) Important Bird Areas factsheet: Somenos Marsh Wildlife Refuge. Downloaded from http://www.birdlife.org on 22/02/2019.