Canada’s Desert Country
Geology, geography, and climate have combined to provide a basis for the unique ecology of the South Okanagan-Similkameen. This area emerged from the last ice age as a wide valley lined with fertile bench-land terraces. When the residual lobes of the ice sheet finally melted, they left depressions now filled by the Okanagan lakes. The rain shadow of the Coastal Mountains gives the South Okanagan-Similkameen a dry climate, but the open waters of these lakes moderate local temperatures, cooling the air in summer and warming it in winter.
The result is diverse habitat elements in close proximity: wetlands, grasslands, rocky outcrops such as cliffs and talus, and other landscapes supporting a unique assemblage of plants and animals. Many of these species are found only in this area, including eight species of invertebrates found nowhere else in the world, and eight species of vertebrates and 28 invertebrates found nowhere else in Canada. In addition, some species persist locally in the favourable South Okanagan-Similkameen habitat in increasing isolation from the rest of their range. The Okanagan River watershed forms a north-south corridor that connects the dry landscapes of British Columbia’s interior with similar natural systems to the south, including the Great Basin, Sonoran, Mojave, and Chihuahuan deserts. The South Okanagan-Similkameen is important ecologically as a corridor, a channel of movement for wildlife. This corridor is crucial for many species of birds in their annual migrations between summer and winter ranges. Migrant birds often rely on strips of contiguous habitats, such as shrubby riparian margins, where they find cover from predators and food to fuel their flight.