Recovery Strategy for Pitcher's Thistle in Canada [Final Version]: Critical Habitat

Critical habitat is defined in the Species at Risk Act (2002) section 2(1) as "the habitat that is necessary for the survival or recovery of a listed wildlife species and that is identified as the species' critical habitat in the recovery strategy or in the action plan for the species". In a recovery strategy, critical habitat is identified to the extent possible, using the best available information. Ultimately, sufficient critical habitat will be identified to completely support the population and distribution objectives.

In the section below, nine parcels of critical habitat are identified for Pitcher's thistle at seven sites throughout its Canadian range. This represents a significant contribution to achieving the objectives; however, additional critical habitat will be needed. Recent surveys funded by the Species at Risk Program discovered far more populations of Pitcher's Thistle than expected. At this time, we do not have adequate information to determine which of those populations should be identified as critical habitat to achieve the objectives. A schedule of studies, which outlines the work required to complete the identification of critical habitat, is included below. In the meantime, implementation of the broad strategies and approaches outlined will aid in meeting the population and distribution objectives.

The critical habitat thus identified represents a significant contribution to the recovery objectives, and other recovery tools will be used to fulfill the objectives as outlined in the Broad Strategies and Approaches section.

Critical habitat was mapped by Parks Canada in cooperation with Ontario Parks and the Ontario Ministry of Natural Resources in April of 2010. Mapping was based on coordinates taken in the field during monitoring. The data available varied by site. Three sites had points for habitat boundaries; two sites had coordinates for individual plants; one site had partial coordinates for plants and boundaries, and one site had only a location point in the center of the habitat. Coordinates were plotted on Quickbird imagery (6 satellite images at 60 centimetre resolution with a date range of June 2005 - August 2008). Critical habitat polygons were drawn based on the rules outlined for detecting substrate changes and forest cover. The 15m distance into the trees at the inland boundary was plotted by the GIS software from a line identified on the imagery as the end of the open dune.

Within dunes, Pitcher's Thistle habitat consists of a series of different vegetation zones, more or less parallel to the water's edge, starting at the lake and running inland towards the forest. Pitcher's Thistle is normally not found right along the water's edge in the active wet strand. The amount of vegetation present in these zones changes gradually from open, loose, nearly-bare sand near the water, to sand covered with patches of low shrubs and trees further inland. Pitcher's Thistle may occur in all of these zones.

The front boundary of critical habitat varies, and can start at the wet beach area, although this varies depending on the type of frontal beach (see Figures 3 to 10). The lateral boundaries of critical habitat are a very obvious change from open sand to soil, bedrock, gravel, or cobbles where dune processes don't occur because there is no sand. Because the change from dunes to other substrate is usually quite abrupt at the lateral boundaries, a transition zone is often not required in this part of the critical habitat. Occasionally in areas of very large habitats that are occupied by Pitcher's Thistle in only a small area, critical habitat boundaries have been drawn to allow sufficient room for dispersal and colonization of new areas. The critical habitat boundary then includes the next nearest adjacent area suitable for habitat dispersal.

Almost all Pitcher's Thistle sites are bordered by forest or woodland behind the dunes. The distance critical habitat extends from the back edge of the open dune into the trees depends on tree type and morphology, stand density, and other variables determined by experts in the field. For the purpose of critical habitat, a distance of 15 metres inland of the point where trees begin to cover 60% or more of the ground is critical habitat.

Pitcher's Thistle habitat is dynamic, with shifting substrate and changing vegetation cover. As a result, the area required for critical habitat may also change, so it is suggested that the appropriateness of the boundaries of critical habitat be re-evaluated on a 10-year cycle, which would also correspond to COSEWIC's assessment cycle.

The 9 critical sites parcels have been identified as follows. They are shown on the locator map (Figure 2), and in more detail in the maps that follow (Figures 3 - 10)

Figure 2. Locator map for the critical habitat in Ontario

Figure 3. Pukaskwa National Park: Hattie Cove, Middle Beach

Figure 4. Pukaskwa National Park: Oiseau Bay, Creek Beach

Figure 5. Manitoulin Island Region: Great Duck Island, Desert Point

Figure 6. Manitoulin Island Region: Great Duck Island, Horseshoe Bay

Figure 7. Southern Lake Huron Region: Inverhuron Provincial Park: Back dune area

Note: The term "Protected Area" used in the critical habitat maps has no relation to protection requirements under SARA

Figure 8. Southern Lake Huron Region: Inverhuron Provincial Park: North population

Note: The term "Protected Area" used in the critical habitat maps has no relation to protection requirements under SARA

Figure 9. Southern Lake Huron Region: Pinery Provincial Park: Front dune area

Note: The term "Protected Area" used in the critical habitat maps has no relation to protection requirements under SARA

Figure 10. Southern Lake Huron Region: Pinery Provincial Park: South populations

Note: The term "Protected Area" used in the critical habitat maps has no relation to protection requirements under SARA

GIS shapefiles of all the critical habitat parcels are maintained by Parks Canada. The rationale for the boundaries at each site is detailed in a separate document on file with Parks Canada, Species at Risk Section, Ottawa (Parks Canada 2010).

Activities that disrupt or destroy stabilizing vegetation leading to erosion, blow-outs, and burial:

• Vehicle, ATV, and snowmobile use on dunes and upper beach portions of critical habitat outside of designated right-of-ways with existing infrastructure;
• Trampling, cutting or removal of native dune grassland vegetation;
• Random camping within critical habitat;
• Use of heavy equipment anywhere in the critical habitat;
• Sand mining, sand removal, and bulldozing sand;
• Raking or "cleaning" the beach of vegetation.

Activities that reduce native species presence and introduce exotic species, leading to degradation of habitat suitability for Pitcher's Thistle:

• Bringing in fill or topsoil;
• Seeding lawns or planting non-native species;
• Planting trees;
• Grazing by livestock.

Activities that change dynamic dune processes, which may disrupt wave action, negatively alter natural sand deposition patterns, or disrupt the flow of littoral sediments:

• Construction of groynes, seawalls, revetments or other fixed structures where critical habitat includes near-shore areas;
• Construction or placing of structures e.g., houses, cottages, saunas, garages or sheds, driveways, hard surfaces, temporary docking facilities, etc.;
• Construction of boardwalks or use of snow fences;
• Building roads across dunes.

Threshold tolerance levels for the above activities have not been determined and may require further research. Due to the differences in threshold levels, it is recommended that the use of dunes for recreational activities within parks be addressed by management planning.

Some activities may affect critical habitat for Pitcher's Thistle, while others may not. Most human activities may continue (if not otherwise prohibited) on the lakeward (wet sand beach) portion of the critical habitat in front of, but not on the dune vegetation, as activities are not likely to impact dune vegetation or dune processes within this zone of the habitat. Additionally, it may be permissible to construct an access route across the dunes to a beach area, especially if the access route will reduce damage from recreational use. Finally, it is recognized that the shoreline is a public right-of-way in many areas. Use of the right-of-way may continue once routes or lanes for vehicle travel have been designated and signage or barriers show their location. The intent is to permit travel in the designated right-of-way only and to prevent other vehicular use elsewhere in critical habitat.

It should, however, be noted that there may be situations where activities on the wet sand beach area or in the shoreline right-of-way could have negative consequences for other species (such as the endangered Piping Plover, which nests on dunes), and as such may be prohibited in Pitcher's Thistle habitat areas due to other considerations. Boardwalks or snow fences may be beneficial or harmful to dune processes depending on the local situation and their placement.

Removal of invasive species, such as the Common Reed (Phragmites australis) may be required for habitat maintenance and protection. As such, removal of Common Reed may be required to effectively protect critical habitat. However, consideration of the methods used for removal will need to be evaluated prior to implementation to ensure that no negative impacts to Pitcher's Thistle, the dune habitat, or other significant species result.

Table 3. Schedule of Studies to Delineate Critical Habitat

Genetic work: The study by Coleman (2007a) did not include southern Lake Huron populations, or populations in the United States. Genetic relationships between southern Lake Huron and Manitoulin, Lake Superior and U.S. Pitcher's Thistle populations require investigation. Genetic analysis will help recovery planning by clarifying the threat from isolation and the conservation importance of individual occurrences, and could assist in determining where to obtain seed stock if reintroduction is warranted.

Update ranking: Element Occurrence (EO) viability ranks for Pitcher's Thistle occurrences need to be updated to guide recovery efforts and to prioritize conservation efforts. Most rankings are now outdated.

Population Viability Analyses: PVAs for Pitcher's Thistle could be developed on both the population and landscape levels (Bell et al. 2002). To accomplish this, the population dynamics of Pitcher's Thistle in Ontario need to be better understood. PVAs could be used to estimate the effects of threats and may be useful in measuring recovery efforts.

Reintroduction: An appropriate reintroduction and restoration protocol needs to be developed, particularly for southern Lake Huron populations where past reintroductions do not seem to have succeeded over the long term. The causes of original extirpation from sites need to be ascertained before reintroduction takes place.

Evaluation of the progress toward achieving Pitcher's Thistle recovery will be undertaken five years following final posting of this recovery strategy on the Species at Risk Act Public Registry, and every five years following, as per SARA (s. 46). Success of the implementation of the recovery strategy will be evaluated against the Population and Distribution Objectives (Table 4).

Table 4. Performance Measures to Evaluate Progress of Pitcher's Thistle Recovery

One or more action plans will be completed by December 2015.