Western Painted Turtle (Chrysemys Picta Bellii)
- Assessment Summary
- Executive Summary
- COSEWIC History, Mandate, Membership and Definitions
- List of Figures
- Species Information
- Population Sizes and Trends
- Limiting Factors and Threats
- Special Significance of the Species
- Existing Protection or Other Status Designations
- Technical Summary
- Acknowledgements, Authorities Contacted, and Information Sources
- Biographical Summary of Report Writer and Collections Examined
Much of what we know of Western Painted Turtle habitat associations has been derived from the study of other subspecies, particularly in the northeastern United States. Painted Turtles are highly aquatic being found in shallow waters of ponds, lakes, oxbows and marshes, in slow-moving stream reaches, or the quiet backwater sloughs of rivers. Ideal Painted Turtle habitat contains muddy substrates, ample emergent aquatic vegetation, exposed cattail mats, logs, and open banks (St. John 2002). Orchard (1986) suggests that an optimum lake or pond has: (1) 80% of its water depth ≤ 3 m; (2) a mud or sand substrate in 80% of the shallow zone (≤ 3 m); (3) aquatic plants (emergents) in at least 80% of the littoral zone; and (4) at least one emergent basking site at a depth of ≤ 1 m/30 m of shoreline.
Although Painted Turtles forage, mate and hibernate in water, movements several hundred metres overland are not uncommon (Gregory and Campbell 1987). These long-distance movements typically represent spring and fall migrations of individuals that breed and hibernate in different ponds. Females, in particular, make extensive use of the terrestrial environment, laying their eggs up to 150 m, or more (R. Brooks pers. comm.), away from the water’s edge. They select an exposed patch of soil or sand either in a field or pasture, or on a beach or roadside, where digging is possible. Gentle slopes (< 45°; Orchard 1986) with southern exposure and good drainage are often chosen: high temperatures increase growth and development rates whereas good drainage decreases soil saturation and thus the probability of ice crystals penetrating the bodies of overwintering hatchlings (Storey et al. 1989, 1998, Costanzo et al. 1995, 1998, 2004).
In a literature review of the biologically relevant size of core habitats surrounding wetlands for amphibians and reptiles, Semlitsch and Bodie (2003) emphasize that terrestrial habitats are critical to all semi-aquatic species and that acknowledging the biological interdependence between aquatic and terrestrial habitats is key for the persistence of populations. A landscape approach to the conservation of Spotted Turtles (Clemmys guttata) and Blanding’s Turtles (Emydoidea blandingii), for example, involves the protection of small wetlands, maintenance of generous terrestrial buffers around individual wetlands, and conservation of wetlands in groups (Joyal et al. 2001). Gibbons (2003) proposes that for the Painted Turtle there are two terrestrial habitats of importance, the riparian periphery and the terrestrial corridors that connect isolated wetlands. In light of these arguments, Painted Turtle habitat ideally consists of a cluster of breeding and overwintering ponds, their riparian zones, and the matrix habitat connecting them. A riparian width of 150 m was deemed necessary by Bodie (2001), based on migration data from 10 species of freshwater turtles in the U.S.
Small wetlands are often converted to more “usable” land for human activities including agriculture, raising of livestock, hydroelectric dams, urban development, and industry. Wetland loss is especially significant near large urban centres. Vancouver, Victoria, Regina, Winnipeg and Thunder Bay occur within the range of the Western Painted Turtle in Canada. Wetland loss has been considerable in British Columbia. At least 75% of the wetlands in the Fraser River Valley of the South Coast - where Vancouver is situated - are gone (Nowlan and Jeffries 1996), and losses continue. Scientists estimate that 75% of the wetlands present in the vicinity of Victoria (i.e., along southeast coast of Vancouver Island) at the time of European settlement have disappeared (Capital Regional District 2005). Although there is no metropolis in the south-central part of British Columbia, human population has been rising steadily in the area; there was a tripling of people in the Okanagan from 1947 and 1987 (Cannings et al. 1998). Only 15% of wetland and riparian habitats remain in the South Okanagan-Similkameen River Valleys of south-central B.C. (Schebel 2005).
Many remaining wetlands are degraded by human activities; forms of habitat deterioration include water pollution, bank erosion, riparian vegetation loss, habitat fragmentation, infilling, water extraction and altered wetland hydrology. Habitat deterioration can be particularly pervasive in the vicinity of urban centres and in high recreation use areas. Based on a three-year water-quality monitoring program in the Lower Mainland between 1992 and 1997, 21% of 24 monitored wetlands had poor water quality most of the time, and 67% of the wetlands were subject to occasional contamination (Nichol et al. 2001).
Roads are a major source of habitat loss and degradation and direct mortality of turtles. For example, along a two-way highway intersecting prairie pothole habitat in western Montana, there is a mean of 346 road kills per year (K. Griffin pers. comm. 2005). The 6.2 million-kilometre network of public roads in the United States, which is used by 200 million vehicles per year, permeates and links essentially every local area (Forman 2000). Forman (2000) estimated that one fifth of the U.S. land area is directly affected ecologically by the public road system. Effects range from road mortality, toxic run-off, sedimentation, increased predation, altered drainage patterns, and increased habitat invasion by exotic species, to distant impacts such as noise pollution and loss of “interior” habitat conditions (Forman and Deblinger 2000). Road networks are less complex and dense in Canada, but they are nevertheless extensive in most of the Western Painted Turtle’s range in Canada, particularly in British Columbia where human and turtle activities are largely confined to river valleys between steep mountain ranges. The severity of this problem is increasing in the southern interior of B.C. as rapid growth is creating more roads and increasing traffic density, causing more road mortality (M. Sarell pers. comm. 2005).
Wetland loss and deterioration, habitat fragmentation and roads will rise with increasing human population and activity. This is not yet a major concern in extreme western Ontario and in southern Manitoba, where a myriad of streams, rivers, lakes and smaller water bodies provide extensive connected habitat, most of which is not affected by humans (A. Didiuk pers. comm. 2005). In Saskatchewan and Alberta, wetlands are primarily subject to rangeland activities, with limited shoreline impacts from human activities. It should be cautioned, however, that dams contribute to habitat loss in large river systems (e.g., Netley and Delta Marshes in Manitoba, Qu’Appelle and Souris Rivers in Saskatchewan, Oldman River in Alberta); an increase in the number of dams could pose a threat in the future. In southern British Columbia, human population has risen steadily since the mid-1900s (Cannings et al. 1997; Nichol et al. 2001), and is expected to double within 15 years (Nichol et al. 2001).
The regions of Ontario that are occupied by the Western Painted Turtle tend to have low population densities of people. The Painted Turtle is protected in Pukaskwa National Park, in 12 provincial parks: Sibley, Waterway, Quetico, Sandbar Lake, Nipigon Lake, Rushing River, Woodland Caribou, Lake of the Woods, Kakabeka Falls, Caliper Lake, Sleeping Giant, and Arrow Lake, and in the Cedar Falls Conservation Area (based on known turtle records). Aside from the Thunder Bay District and communities along the Trans-Canada Highway, the southwestern portion of northwestern Ontario is dominated by forests and wetlands (and small cottage communities).
Apart from Winnipeg and its satellite towns, Manitoba has a moderate to low human population density (only 10 to 25 families per km2; Hammond Atlas of Canada and the World) because the area is dominated by farmlands. Lake, river and wetland networks are extensive in most of the province and the Western Painted Turtle is protected in three extensive parks (Riding Mountain National Park, Nopiming and Whiteshell Provincial Parks) and several smaller ones including Assessippi, Grindstone, Hecla, Spruce Woods, Birds Hill, and Turtle Mountain provincial parks.
Southern Saskatchewan has a dry climate and Western Painted Turtles in this province are limited to four main river watersheds near the border (Qu’Appelle, Souris, Swift Current, and Frenchman Rivers). There is a moderately low human population density beyond the city limits of Regina because of the agricultural nature of the province. The large Grassland National Park protects C. p. bellii in the Frenchman River drainage near the U.S. border. At least three small parks (Buffalo Pound, Moose Mountain, and Roche Percée) offer some protection elsewhere in the province (based on known records).
In southern Alberta, the Western Painted Turtle is protected within Waterton Lakes National Park and the very small Milk River Natural Area. There are two small provincial parks within the species’ range in Alberta (Beauvais Lake and Writing-on-Stone) though turtles have not been reported in either one of them. Although there is little habitat protection in Alberta, this province’s human population density is low (< 3 families per km2; Hammond Atlas of Canada 2000).
Based on known records, a number of small parks afford turtles some protection in British Columbia, including several provincial parks (e.g., Haynes Point, Kikomun Creek, Champion Lakes, Shuswap Lake, Grohman Narrows, and Okanagan Mountain), the Vaseaux Bighorn National Wildlife Area, and the Creston Valley Wildlife Management Area. In the Rocky Mountain Trench of southeastern B.C. the species appears to be secure as roughly 60% of wetlands in the Columbia River basin are protected by conservation efforts (J. Krebs pers. comm. 2005), and there is a very large wildlife management area in Creston. The Southern Interior is largely agricultural (vineyards, orchards, rangelands), though urban centres are dominant and growing along certain lakes and river sections. On the south coast (including the mainland south of Fraser River and Vancouver Island), much of the land is intensively developed; some potentially beneficial parks include Rolley Lake, Cultus Lake, and Chilliwack Lake Provincial Parks.
Western Painted Turtle habitat in Canada can also be protected via: (1) fisheries regulations along commercial fish-containing wetlands and watercourses; (2) municipal parks; (3) local wildlife management initiatives; and (4) environmental by-laws (e.g., zoning by-laws that work around environmentally sensitive areas).
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