Vaseux–Bighorn National Wildlife Area Management Plan: chapter 4
4. Management approaches
This section describes the approaches that will be used in the management of the National Wildlife Areas (NWA). However, specific management actions will be determined during the annual work-planning process and will be implemented as human and financial resources allow.
4.1 Habitat management
Forests will be managed to reduce the growth of young trees in order to maintain an opencanopy forest with less than 25% canopy closure, composed primarily of older trees. Forest expansion will be limited by controlled burns and cutting where deemed necessary and practicable.
4.1.2 Riparian and cottonwood habitats
Where control and facilitation of flooding is possible, riparian and cottonwood forests will be maintained, and their growth encouraged. Partnership agreements with local and regional water management authorities will be explored to manage water for flooding of key habitats. Local water management will be managed through the construction of local wells, small-scale irrigation and dam projects. The development of these on-site projects will be discussed with partners such as Ducks Unlimited Canada.
4.1.3 Wetlands and meadows
Management of wetlands and meadows will be directed at:
- restoring, to the extent practical, the historic hydrological regime, and
- reducing or eliminating alien invasive species.
Past management of the wetlands included digging a series of test holes as part of a study to bring water to the surface in order to return the meadow at the north part of Vaseux Lake nearer to its original hydrology, while adding habitat diversity and creating habitat for the endangered Yellow-breasted Chat (Glenfir Resources 2003). The study indicated that increased moisture retention could also help to temporarily suppress the in-growth of currently dominant species (e.g., Reed Canary Grass and Lousel’s Tumble Mustard). Therefore, soil and moisture regimes and flood levels will be managed to mimic historical hydrological systems to the extent practical, in order to support native plants and animals and reduce the occurrence of invasive species (J. Emery, Personal communication (pers. comm.) 2010).
Hydrological management must include close cooperation with Ducks Unlimited Canada and monitoring of their Vegetation Management Project in the Northwest Marsh Unit. Removal of some of the dykes along the river would allow the wetlands to be self-sustaining and fully functioning but may require purchase of one or more riverside parcels (Glenfir Resources 2003).
4.1.4 Talus slopes and cliffs
Talus slopes and cliffs will not be actively managed, but human disturbance of these habitats will be minimized through monitoring, signage, education, other compliance promotion efforts, and enforcement of prohibitions.
4.1.5 Grasslands and shrub lands
Grasslands and shrub lands will be managed to preserve the existing extent of Antelope Brush and increase its extent through restoration where possible. Alien and invasive plant species will be controlled with the aim of eventual elimination.
4.2 Water quality
Drainage waters from Highway 97 are a probable source of pollution into the adjacent wetland areas of the NWA (North Wetlands Unit). The principal pollutants are sediments, heavy metals, and hydrocarbons, which are all persistent pollutants. These are especially damaging to the wetland areas when short, heavy rainstorms follow long dry periods, since this flushes a large amount of drainage into the ecosystem.
Agricultural water and wastewater may also contribute to water quality issues in the Okanagan River and Vaseux Lake adjacent to the NWA.
Water quality will be improved wherever possible through riparian plantings, because an increase in riparian plants between the highway and lake will mitigate pollution to some degree, and also through compliance promotion if considered necessary. Other methods may also be explored.
4.3 Alien and invasive plants
The South Okanagan-Similkameen Invasive Plant Society provides strategic management planning for invasive species in the South Okanagan, including the NWA. The overall goal of the weed management plan in the Okanagan-Similkameen region is to “…cooperatively control, contain, and reduce weeds in the region, and to encourage knowledge and partnership for an integrated, effective weed control program” (South Okanagan-Similkameen Invasive Plant Society, undated).
Where invasive species (especially non-native plants, i.e., weeds) might disrupt native plant communities or associated native flora/fauna, attempts will be made to control or eradicate these invasives. Sulphur Cinquefoil is the highest-priority plant for control because of its known ecological impacts and widespread occurrence within the NWA (Perry 2004). Other predominant invasive plants present in the NWA include Dalmatian Toadflax, Diffuse Knapweed, Hound’s Tongue and Bull Thistle.
An Integrated Pest Management approach using a combination of chemical treatment, hand-pulling and biological controls is being used to help manage these species. Continued treatments will be necessary to control these species or eradicate them from the NWA. Using alternate control treatments (as opposed to chemical treatments) will be encouraged wherever feasible. To help protect aquatic habitats and associated wildlife, use of chemicals will not be permitted near water.
4.4 Wildlife management
The management of wildlife within the NWA, particularly for those species that range off the federal lands and that are ordinarily managed provincially, will be carried out in close collaboration with the Province of British Columbia. Where there may be broader implications, the Canadian Wildlife Services (CWS) will consult with adjacent landowners and other key stakeholders.
The management units of the NWA are, in many places, contiguous with the Nature Trust of British Columbia (B.C.) and provincial Parks and Protected Areas. Major movement restrictions between the NWA and surrounding lands are mostly due to Highway 97, which runs along the east side of Vaseux Lake adjacent to the Northeast Upland Unit and parallel to the Okanagan River east of the North Wetland Unit. This creates situations in which wildlife movements are potentially restricted. Another concern is the encroachment of the surrounding agricultural and urban development areas onto potential movement corridors leading in and out of the wildlife area.
Managing the movement of wildlife includes addressing the issue of roadkill, adjacent land encroachment, and the linear corridors created by the old railway bed and the gas line right-of-way. In addition to existing deer fencing to reduce roadkill, management measures could include building a wildlife overpass over Highway 97 to allow unrestricted movement of wildlife, particularly large mammals. Other options include erecting signage, or traffic devices to reduce vehicle speed through areas that are known to have high wildlife crossover rates.
Management strategies will maintain existing natural features in wetland and upland habitats that meet the requirements of all breeding and migrating waterfowl. Since the channelization of the Okanagan River between Skaha Lake and Osoyoos Lake, hydrological values have been altered, which also affected breeding and stopover sites for waterfowl and other migratory birds. One generalized habitat enhancement program in the NWA that has been ongoing for more than two decades is the restoration of the Vaseux Lake marsh (the southern half of the Northwest Marsh Unit) by Ducks Unlimited Canada (30-year agreement since 1984, with the CWS). Ducks Unlimited Canada manages for waterfowl and periodically updates their management initiative (every 5-7 years) to adjust to changing management issues (K. Johnson, pers. comm. 2009). Their current management activities in this unit mostly include reducing the density of cattails in order to create appropriate open-water areas for waterfowl (K. Johnson, pers. comm. 2009).
Wetlands within the NWA will be managed to maintain diverse habitats. Manipulation of habitats will only occur in areas that show disturbances. Management will include restriction of livestock access, maintenance of water levels, and restricted activities in buffer zones (300 m) around wetland areas (Chapman et al. 2004).
Within the NWA, 17 species of mammals have been recorded. Of these, one is listed under the Species at Risk Act as endangered (American Badger), one is listed as threatened (Pallid Bat), and three are listed as special concern (Western Harvest Mouse, Spotted Bat and Nuttall’s Cottontail). In addition, California Bighorn Sheep, a local flagship species, is provincially blue-listed (B.C. Conservation Data Centre 2010).
Except for an inventory conducted within the NWA in 2003 (Dawe et al. 2004), populations of mammals within the NWA are not well studied. As such, the actual number of mammalian species using the site is undoubtedly greater than currently enumerated. Management for large mammals will include control of invasive plants to improve foraging habitat, and exclusion of domestic animals. Major habitat alterations will not likely occur, unless circumstances deem such major alterations (thinning, logging, burning) appropriate.
California Bighorn Sheep inhabit rugged and rocky terrain as well as the adjacent grassland and open-forest foraging areas, and are found primarily on the east side of Vaseux Lake. This subpopulation is the largest in the South Okanagan meta-population. It inhabits the south- and west-facing bluffs between Shuttleworth and Vaseux creeks east of Highway 97 and Vaseux Lake and the Gallagher Range to the west. In 1965, 173 Bighorn Sheep were counted in this subpopulation (Spalding and Bone 1969). Counts through the 1980s and 1990s revealed similar numbers, but a severe disease-related die-off occurred in the late 1990s. The highest count subsequent to the die-off was 44 animals in February 2000, and numbers near Vaseux Lake continued to decline through to December 2000 (Harper et al. 2002).
Winter ranges for the Vaseux Lake sheep subpopulation are generally in poor condition, and have been so since at least the 1960s. Spalding and Bone (1969) noted major infestations of Diffuse Knapweed in a number of areas, particularly those areas in the vicinity of power transmission lines, which has reduced natural forage.
Populations now seem to be rebounding. In 2003, ewes and lambs were often seen on the lambing cliffs of the Northeast Uplands Unit, as well as on the Nature Trust’s Emery property where flocks of sheep were observed frequently in the spring and summer (Dawe et al. 2004). A provincial recovery plan is in place (Harper et al. 2002), and substantial opportunities to conserve habitat exist in the NWA, mainly through control of invasive plants to improve foraging habitat and exclusion of domestic animals. The South Okanagan meta-population has rebounded since 2002, with a count of 205 recorded by aerial survey in March of 2009 (Gyug 2009).
4.4.3 Species at risk
Vaseux-Bighorn NWA provides year-round and seasonal habitat for 30 species listed under Schedule 1 of the Species at Risk Act. Species-specific recovery strategies and action plans are, and will continue to be, key drivers of management activities in the NWA. Management will be adapted as more recovery strategies and action plans are completed and posted on the Species at Risk Act Public Registry.
Multi-species approaches to recovery are being developed by the CWS, the South Okanagan- Similkameen Conservation Program and other similar organizations. These strategies will also help to guide recovery efforts for species at risk in the Conservation Program area for many years into the future.
Appendix I outlines species at risk for which active habitat management would likely produce tangible benefits. Species at risk will be managed in an integrated fashion with other species at risk and other wildlife. Overlapping and conflicting habitat needs will be evaluated, and habitat management will be based on providing the greatest amount of benefit to the greatest number of species at risk, while considering high-priority species (those at greatest risk).
Effective and efficient monitoring requires careful planning and a coordinated approach, and will be carried out in a manner that contributes to meeting recovery strategy and action plan objectives. A separate document that outlines the ecological and site monitoring approach for the NWA will be produced at a later date; it will be driven by recovery strategies and action plans for multiple species.
Ongoing monitoring needs are as follows:
- Monitor distribution and abundance of species at risk such as Yellow-breasted Chat, Behr’s Hairstreak and Sage Thrasher
- Monitor the extent and distribution of Snow Buckwheat, Big Sagebrush, riparian and cottonwood forests, and permanent and ephemeral wetlands
- Monitor snake populations and track population size by species over time
- Monitor, at select locations, the volume of un-permitted access for off-trail recreational use
- Monitor the distribution and density of alien invasive plant species within the NWA
- Monitor surface water for concentration of pesticides, herbicides, nitrogen, phosphorus, and sediment
Research activities will be considered for permitting only when the results from the research have the potential for the following:
- Protecting, maintaining, restoring or enhancing naturally occurring habitats
- Recovering species at risk or conserving migratory birds
- Reducing the encroachment of invasive species in the NWA
- Assessing the trends in species populations (especially species at risk) and habitats of concern
- Maintaining wetlands in a state most beneficial to wetland-dependent wildlife
- Reducing illegal public trespassing onto NWA lands.
4.7 Public information and outreach
Public access for recreational purposes to the majority of Vaseux-Bighorn NWA is subject to the federal Wildlife Area Regulations and is generally not permitted. In cooperation with the Province of British Columbia and the Nature Trust of B.C., Environment Canada established a bird viewing tower and parking lot on the northeast end of Vaseux Lake. There is an information kiosk belonging to B.C. Parks and a boardwalk leading from the parking lot to the bird viewing tower. The boardwalk trail meanders in and out of the NWA. The parking lot lies across the boundary between the NWA and kiosk.
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