Canada's Endangered Desert Country

Dramatic shifts in the earth's crust, retreating glaciers and the relentless rush of the Okanagan and Similkameen rivers have combined forces over thousands of years to create a tiny pocket in south-central British Columbia that is unlike any other place in the world.

The South Okanagan-Similkameen valley is just two-thirds the size of Prince Edward Island, yet it is one of the few areas on earth where four very different habitats exist in close proximity. A combination of coniferous forests, desert-like grasslands, wetlands, and rocky cliffs make this one of the richest ecosystems in Canada. Nearly half the bird species in the country are found here, along with many plants and animals that exist nowhere else in North America or, in some cases, the world. The South Okanagan-Similkameen watersheds also act as a corridor for species migrating between the dry grasslands of the BC interior and the desert areas of the western United States.

Unfortunately, rapid urbanization has also turned the area into one of the most endangered regions of the country. The reduction and fragmentation of habitat due to housing, agriculture and other human activities has resulted in an intense concentration of species at risk: 23 species of plants and animals currently listed as nationally threatened, endangered or of particular concern, and one-third of provincially red-listed species, make their homes here. Over half of these depend on grassland and shrub-steppe habitat, which is one of the most dramatically altered.

What attracted these species to the region in the first place? Sheltered from the rain by the coastal mountain range, the South Okanagan and Similkameen valleys have a dry climate with temperatures moderated by the open waters of the Okanagan lakes. At the cooler, higher altitudes are coniferous forests; at the hotter, lower altitudes, grassland and shrub-steppe habitat that typically receives less than 30 centimetres of rain a year. Also at these lower elevations are wetlands and a rugged terrain of sheer cliffs, boulder fields and talus slopes.

Many species rely on the proximity of these habitats to survive. For example, certain species of toads and salamanders spend most of their year in the grasslands, but need the small alkaline lakes nearby for breeding. Fifteen of the 20 species of bats found in Canada hang out in the Okanagan Valley, hiding in the cracked cliffs on hot summer days and emerging at night to feed on insects buzzing over the wetlands. The threatened Pallid Bat, whose only Canadian home is in the South Okanagan, has even more specific needs: it is the only bat that hunts for insects on the ground among the sagebrush of the grasslands.

Scientists with Environment Canada and the province of British Columbia began studying the Okanagan in the late 1960s, and in the early 1970s some land in the area was purchased for the Vaseux-Bighorn National Wildlife Area. It wasn't until 1985, however, that the first concerted effort was made to conserve habitat with the introduction of the South Okanagan Conservation Strategy. Under this Strategy, the habitat area was mapped, status reports were prepared for species at risk, and species recovery teams were launched. In the years since, efforts have focused on managing Crown land, acquiring priority habitat, and encouraging stewardship on privately owned property.

As the shared habitat needs of many species at risk have become more apparent, there has been a gradual shift away from individual species recovery efforts to a more ecosystemic approach that focuses on habitat restoration. The rationale behind the new approach is that individual recovery teams were duplicating efforts, because many species share the same habitat needs. At the same time, some were acting at cross-purposes, because altering any ecosystem to benefit one species without considering the needs of others could have a potentially harmful effect on other species in the area.

This summer, 19 conservation organizations and government agencies agreed to adopt a holistic approach with the formation of the South Okanagan-Similkameen Conservation Program (SOSCP). Environment Canada is a founding member of the program, along with the BC Ministry of Environment, Habitat Conservation Trust Fund, Nature Trust of British Columbia, Nature Conservancy of Canada, and Land Conservancy of British Columbia.

In addition to promoting stewardship and negotiating the acquisition of priority habitats (which comprise about one-third of the region's area), the program is also expanding community involvement. This summer, Environment Canada announced that it will contribute $1 million from its Habitat Stewardship Program to fund a variety of SOSCP activities that will be carried out by non-government organizations, private landowners, conservation groups and local governments.

Boundary of South Okanagan-Similkameen Conservation Program in Southern British Columbia

Since it is the most important habitat for species at risk in the region, grassland/shrub-steppe ecosystems are a priority for restoration efforts. These savannah-like areas are dotted with mostly low-lying vegetation, such as tussock-forming grasses, sagebrush and other shrubs with long root systems, as well as scattered stands of old-growth Ponderosa pines. These trees are vital habitat for the White-headed Woodpecker, an endangered species whose only Canadian home is southern BC and, in particular, the Okanagan and Similkameen valleys. The woodpecker relies on these mature trees not only for nesting, but for their large seeds, which are an important source of food in winter.

Unfortunately, logging activities and the subsequent suppression of fires, which have historically played an important part in the life cycle of the grasslands, have greatly altered this ecosystem over the past 50 years. Not only have many older-growth Ponderosa-pine stands been replaced by thick stands of young pine and fir, but invasive weeds have spread rapidly through the grasslands, endangering some native plant species.

In taking an ecosystemic approach to conserving biodiversity in the region, the conservation project is considering the needs of a number of species at risk in the area, including the White-headed Woodpecker and the California Bighorn Sheep—a provincially blue-listed species that suffered a catastrophic decline last winter. One aspect of its plan is a weed management program that involves removing weeds, harvesting seeds from wild plants, and reseeding damaged habitats. A new program will also be launched to carry out selective burns to create better conditions for Ponderosa pines, and to thin stands so that young pines will be able to grow faster and older pines will have more room to flourish.

Multi-species issues are also a concern in the conservation of wetland and riparian habitat in the South Okanagan-Similkameen. This habitat is the most naturally productive in the region, since many species depend on it for part or all of the year. One of these is the threatened Yellow-breasted Chat, a member of the warbler family that nests in lowland riparian thickets and is found primarily in the South Okanagan and Similkameen valleys. A portion of the Okanagan River is also home to one of only two viable sockeye salmon runs in the entire Columbia River watershed.

These areas have suffered massive degradation due to the effects of agriculture and commercial and industrial development on shoreline ecosystems. To tackle the problem, the conservation project has developed a program to secure, rehabilitate and enhance riparian habitat along the Okanagan River that includes planting vegetation and fencing creeks on private ranchlands. The latter, which could entail providing alternate water supplies, will help to prevent cattle from causing further damage and allow riparian plant communities to bounce back.

In addition to these hands-on rehabilitation efforts, Environment Canada is working with other partners to develop a planning tool for the South Okanagan-Similkameen region that will allow users to predict the impact of various land uses on different habitats. The Osoyoos Indian Band has already expressed interest in using the tool to manage the undeveloped areas of its reserve—a good sign, since the Okanagan First Nation as a whole is the region's largest private landowner.

Although the SOSCP's projects are still in their infancy, they mark an important step toward restoring the fragile habitat of the South Okanagan-Similkameen region—and through this habitat the diversity of plant and animal species that cling to life in Canada's vanishing desert country.

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