Vaseux Lake Area (BC262)
Oliver, Colombie-Britannique
Description du site
Vaseux Lake lies in a very narrow section of the Okanagan Valley, between the towns of Okanagan Falls and Oliver. The lake, which is 4 km long and 1 km wide, is fed and drained by the Okanagan River. It is surrounded by a diversity of habitats, such as a cattail-bulrush marsh at the north end where the Okanagan River feeds into the lake, and some water birch woodlands surrounding the marsh. Arid grassland benches to the east and west give way almost immediately to rugged rock cliffs and ponderosa pine woodlands. To the east, the pine forests change to Douglas-fir and western larch forests above 1000 metres. Other fauna of conservation interest include Bighorn Sheep, Pallid and Spotted Bats, Great Basin Pocket Mouse, Night Snake and Racer.
Oiseaux
Significant Species - Vaseux Lake supports nationally significant populations of Lewis's Woodpecker, Western Screech Owl, and Yellow-breasted Chat. Lewis's Woodpecker, determined to be Threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC; wildlife species that have been assessed as at risk by COSEWIC may qualify for legal protection and recovery under Canada's Species at Risk Act) regularly breed here; between one and 25 individuals have been observed annually since 2000. Small numbers (1-5 individuals) of the Okanagan population of Yellow-breasted Chat (subspecies auricollis), listed as Endangered by COSEWIC, have been detected in the IBA since 2001. Threatened (COSEWIC) Western Screech Owls (macfarlanei subspecies; interior population) have been detected in the IBA most years since 2002, primarily during the fall and winter.
Other Species of Conservation Interest - Endangered (COSEWIC) White-headed Woodpeckers were historically seen year-round but irregularly in the Vaseux Lake area, but have not been detected recently. Small numbers of Special Concern (COSEWIC) Flammulated Owls breed in the IBA. Threatened (COSEWIC) Barn Owls are occasionally detected during the fall and winter, and possibly breed here as they have been detected in the summer as well. Peregrine Falcons (anatum subspecies, Threatened, COSEWIC) nest on McIntyre Bluffs at the south end of the lake; at least one falcon has been observed each year since 2004. Threatened (COSEWIC) Barn Swallows and Common Nighthawk also occur in the area.
Vaseux Lake supports resting and overwintering waterfowl, with both Trumpeter and Tundra Swans wintering on the lake. Marshes at the north end of the lake, remnants of a once significant chain of wetlands in the Okanagan valley bottom, support species characteristic of this declining habitat, including American Bittern, Northern Harrier, Virginia Rail, and Yellow-headed Blackbird. The easy access along Highway 97 and the high diversity of birds and habitats makes Vaseux Lake a premier birding site in Canada.
Enjeux de conservation
Loss or degradation of habitat is the key threat for the species at risk at Vaseux Lake IBA. Forest practices and fire suppression have degraded the mature, open Ponderosa Pine forests preferred by White-headed Woodpeckers, increased the risk of catastrophic fires that could destroy nest trees (COSEWIC 2010b), and limited the creation of new habitat for Lewis's Woodpecker (COSEWIC 2010a). A forest fire on the east side of the lake in 2003 killed some mature pines, which are now used by Lewis's Woodpecker for nesting. Benchland and forested habitats are threatened by possible conversion to vineyards or residential developments. Agricultural practices that increasingly depend on pesticides may decrease insect prey abundance or expose woodpeckers to sub-lethal levels of dietary pesticide, though this has not been documented in Lewis's Woodpecker (COSEWIC 2010a). Removal of dead and dying trees for firewood, human-safety, aesthetic, or other reasons has a negative impact on Lewis's Woodpecker and other cavity nesters (COSEWIC 2010a, COSEWIC 2008). Expansion of highway 97 and/or the construction of a trail system along the west side of the lake could impact riparian habitat that is important for Yellow-breasted Chat. The existing dike limits the amount of riparian habitat long the Okanagan River. Researchers have found several dead chats and owls that have collided with vehicles in the area, which identifies roads and increased traffic as a potential threat to Yellow-breasted Chats and owls (Potvin and Bishop 2010, COSEWIC 2002). Competition with European Starlings for nest cavities may be becoming more of a threat to Lewis's Woodpeckers in this area (COSEWIC 2010a). Burdock, an invasive plant, is a potential threat for Yellow-breasted Chats and other birds; bats and birds have been trapped and killed in this plant at Vaseux Lake in the past (Luszcz, pers. com.). Other invasive species that could impact chats include yellow flag iris and purple loosestrife (habitat impacts) and domestic cats (direct impacts).
Yellow-breasted Chats, Western Screech Owls, and Lewis's Woodpeckers are listed under Canada's Species at Risk Act, which involves development of recovery strategies for these species including the identification of critical habitat and what needs should be addressed. A large portion of this IBA is managed for conservation under a variety of jurisdictions. The province manages White Lake Grasslands Protected Area, Vaseux Protected Area, and Vaseux Lake Provincial Park. In addition, several provincially managed Wildlife Habitat Areas were established on the east side of the Lake. Vaseux Lake itself is a federal Migratory Bird Sanctuary and numerous parcels in the IBA comprise the Vaseux-Bighorn National Wildlife Area. The Nature Trust of British Columbia owns and manages land within the IBA to benefit wildlife. The Land Conservancy owns Eagle Bluff, which is managed as the South Okanagan Rehabilitation Centre for Owls. The Vaseux Lake Bird Observatory is one of three migration monitoring stations in BC and operates daily in August, September and the first half of October. Restoration work completed at the site to date includes the creation of pond, channel and associated riparian habitat at the north end of the lake and forest management activities to improve habitat for woodpeckers. Future restoration possibilities include a prescribed burn on the west side of the lake to further improve woodpecker habitat, continued restoration of meadows at the north end of the lake, and restoration of areas degraded by fire or invasive plants, diked areas, and private lands.
Catégories ZICO Habitats Usages Menaces Potencielles ou Existantes Status de Protection
