White Lake Area (BC167)

White Lake Area (BC167)

Penticton, Colombie-Britannique

Description du site

White Lake is located in the southern Okanagan Valley, about 15 km south of Penticton and 15 km north of Oliver. The area is an elliptical bowl (about 3 km by 4 km) of sagebrush grassland set in hills forested with open ponderosa pine woodland. White Lake, a small alkaline lake approximately 300 m in diameter, is at the centre of the bowl. Two small creeks flow through either side of the bowl, but do not feed or flow out of the lake. The surrounding hills are Eocene volcanic origin and the soils are grassland brown chernozems. Much of the area is used as rangeland and an astrophysical observatory is located in the northeast part of the site.

The area is also known to support some unusual species of herptiles (reptiles and amphibians) and mammals. It is the one of the best sites in British Columbia for Tiger Salamander, Great Basin Spadefoot Toad, Western Harvest Mouse, Great Basin Pocket Mouse, and Western Rattlesnakes (also known as Northern Pacific Rattlesnake) have several hibernacula in the area. American Badgers have also been seen at this site.

Oiseaux

Significant Species

White Lake supports nationally significant populations of Sage Thrasher, a species listed as Endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC; species listed by COSEWIC may qualify for legal protection and recovery under Canada's Species at Risk Act). Between one and ten Sage Thrashers have been observed annually since 2003. Threatened (COSEWIC) Western Screech Owls (macfarlanei subspecies; interior population) have been detected three years since 2001, and a nest was discovered in 2006. Single Yellow-breasted Chats (Endangered, COSEWIC) were observed in 2004 and 2005.

Other species of interest

Endangered (COSEWIC) White-headed Woodpeckers are occasionally reported from the White Lake area, but are rarely detected during targeted surveys. Threatened (COSEWIC) Barn Swallows and Threatened (COSEWIC) Common Nighthawk occur in the area. Thousands of Sandhill Cranes have been known to stop at the lake during spring and fall migration. Special Concern (COSEWIC) Flammulated Owls have been detected just outside the IBA and are suspected to occur within the IBA too. Special Concern (COSEWIC) Peregrine Falcons historically used the site. Provincially rare (red-listed) Brewer's, Grasshopper, and Lark Sparrows also occur at the site. This site formally supported nationally Endangered Burrowing Owls and the last recorded sighting was in 1907.

Enjeux de conservation

Loss or alteration of habitat is a threat for Sage Thrasher, Western Screech Owl and other species at risk at White Lake. Removal of mature sagebrush for agricultural expansion or improving rangeland is a threat on private lands and removal of roadside vegetation is a threat alongside roads (COSEWIC 2010). Invasive plants like sulfur cinquefoil, cheatgrass, Japanese brome, and crested wheatgrass have altered the grasslands. Cheatgrass in particular increases fine fuels and the risk of fire. Fire is a threat to Sage Thrasher habitat because it destroys Big Sagebrush (COSEWIC 2010). Forest practices, fire suppression, and climate change have degraded the mature, open Ponderosa Pine forests preferred by White-headed Woodpeckers and increased the risk of catastrophic fires that could destroy nest trees (COSEWIC 2011). Overgrazing is a potential threat, but grazing is better managed now than in the past in most areas and Sage Thrashers are less sensitive to grazing pressure than other grassland birds (COSEWIC 2010). On privately owned lands, mature trees with suitable nesting and roosting cavities for Western Screech Owl are at risk of being destroyed for urban or agricultural expansion or removal due to safety concerns (COSEWIC 2008). Collisions with vehicles may also be a threat; four road-killed owls were reported along a 6-km length of road in one year in the south Okanagan and others have been reported throughout much of the range (COSEWIC 2008). Increased disturbance of nesting birds from recreational users, increased road traffic, and decreased ground water from further development at nearby St. Andrews or Twin Lakes (housing, vineyards, and golf courses) are potentially threatening.

Sage Thrashers, Yellow-breasted Chats, Western Screech Owls, Lewis's Woodpeckers and Common Nighthawks are listed under Canada's Species at Risk Act): as such, species specific recovery strategies are drafted to identify critical habitats and unique conservation needs etc. Approximately one quarter of the IBA is protected within the provincial White Lake Grasslands Protected Area. Most of the remaining area is privately owned by the National Research Council (NRC). These NRC owned lands are leased to The Nature Trust of British Columbia and Clifton Ranch, and managed as the White Lake Basin Biodiversity Ranch. The White Lake Basin Biodiversity Ranch Plan and associated Range Use Plans detail a ranching rotation schedule that has considerably reduced grazing pressure compared to historic levels. Recent conservation activities conducted by The Nature Trust, the South Okanagan Similkameen Invasive Plant Society, and other partners involved in the South Okanagan-Similkameen Conservation Program, include fencing and associated regeneration of riparian habitat, implementation of grazing rotation practices, and biological and manual control of invasive plants.

Catégories ZICO Habitats Usages Menaces Potencielles ou Existantes Status de Protection

• Moqueur des armoises10 (max.)
• Ictérie polyglotte3 (max.)
• Petit-duc des montagnes2 (max.)
• Grue du Canada4 000 (max.)